University of Isfahan Journal of Plant Biological Sciences 3041-9603 17 3 2025 09 23 Improvement of seed germination and biochemical characteristics of Pinto bean seedlings under polyethylene glycol-induced drought stress via the application of nutrient elements containing polyamines Improvement of seed germination and biochemical characteristics of Pinto bean seedlings under polyethylene glycol-induced drought stress via the application of nutrient elements containing polyamines 1 24 30129 10.22108/ijpb.2025.145719.1412 FA Fateme Mahmoudi Department of Plant Production and Genetics, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran Parisa Sheikhzadeh Department of Plant Production and Genetics, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran Meysam Eini Department of Plant Production and Genetics, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran Journal Article 2025 06 21 To investigate the effects of seed-applied nutrient compounds on germination and biochemical characteristics of bean seedlings under polyethylene glycol-induced drought stress, a factorial experiment was conducted in a completely randomized design with three replications. The treatments included drought stress (0, −4, −8, and −12 times) and the application of nutrient compounds containing polyamines (0, 25, 50, 75, and 100 mM). The results showed that drought stress significantly reduced germination rate and percentage to 3.1-6.97%, and reduced seedling dry weight and length to 4.70-28.19%, while increasing the average germination time by about 22.31% compared to the control treatment. However, enriching seeds with nutrient compounds increased seed germination and seedling growth and reduced the average germination time. In the presence and absence of drought stress, the antioxidant enzyme activity and proline content of seedlings obtained from treated seeds were about 3.25 to 4.10 percent higher than those obtained from control seeds. At all levels of drought stress, enriching seeds with different concentrations of nutrient compounds increased germination and improved bean seedling growth by increasing antioxidant enzyme activity. Among the treatments studied, the application of 100 mM nutrient compounds under non-stressed and 12-fold drought stress conditions increased dry weight by 20.69 and 59.26 percent, seedling vigor index by 15.59 and 28.96 percent, and peroxidase enzyme activity by 7.46 and 11.73 percent, respectively, compared to the control treatment, indicating a greater effect of nutrient compounds under drought stress conditions. In general, the application of 100 mM nutrient concentrations had the greatest positive effect on germination, growth, and biochemical traits of seedlings under both favourable and unfavourable conditions. Introduction Drought is one of the most critical environmental stresses limiting crop production worldwide and has adverse effects on germination, emergence, and plant growth and development. In agriculture, drought is defined as the lack of moisture required for normal plant growth and development, and water stress occurs when water loss exceeds water uptake, when water uptake by the plant decreases, or both. The germination and seedling growth stage is one of the most important and decisive stages of plant growth affecting crop production; however, it is strongly influenced by environmental stresses and has therefore been suggested as a suitable criterion for determining plant drought tolerance. Pinto bean (Phaseolus vulgaris L.) is one of the most important grain legumes, playing a major role in the human diet and providing a significant source of protein. Among legumes, the common bean ranks first in terms of cultivated area. This plant is rich in protein, phosphorus, vitamins, and nutrients such as calcium, zinc, copper, iron, manganese, and magnesium, as well as fibre. In addition, due to the symbiosis between atmospheric nitrogen-fixing bacteria and the roots of this plant, it effectively contributes to soil fertility, with large amounts of nitrogen added to cultivated soils each year after harvesting. Several factors can reduce chickpea seed germination and seedling emergence, among which drought stress is one of the most critical. Given that drought stress is one of the most important environmental factors in modern agricultural ecosystems and can significantly reduce plant growth and productivity, preventing or minimizing its harmful effects has long been of interest to researchers. Accordingly, considering the sensitivity of the germination and early growth stages of chickpea seedlings to drought stress, the present study was conducted to investigate the effect of seed application of nutrient compounds containing polyamines on the germination and biochemical characteristics of seedlings of this plant under drought stress. Materials and Methods To investigate the effects of applying nutrient elements containing polyamines on seed germination and the biochemical characteristics of Pinto bean seedlings under polyethylene glycol-induced drought stress, a factorial experiment was conducted in a completely randomized design with three replications. Treatments included drought stress at four levels (0, -4, -8, and -12 bar) and the application of nutrient elements containing polyamines at five levels (0, 25, 50, 75, and 100 %). In this study, the measured traits include germination percentage, germination rate, allometric coefficient, seedling length, seedling dry weight, seedling length vigour index, seedling weight vigour index, and mean germination time (MGT). Also, the activities of the catalase, peroxidase, and polyphenol oxidase enzymes, and the proline content of Pinto bean seedlings were investigated. Statistical analysis was performed using SAS 9.4. Data distribution normality was evaluated using the Kolmogorov-Smirnov test. The comparison of means was performed using Duncan's multiple-range test at the 5% significance level. Excel software was used to draw graphs. Results and Discussion The results showed that drought stress significantly reduced germination rate and percentage, and the dry weight and length of Pinto bean seedlings, and increased the mean time required for germination. However, enriching seeds with nutrient elements containing polyamines increased seed germination and seedling growth, and reduced the mean germination time. Under normal conditions and under drought stress, the activity of antioxidant enzymes and the proline content in seedlings obtained from seeds treated with nutrient elements containing polyamines were higher than in the control. At all levels of drought stress, enrichment of pinto bean seeds with different concentrations (25 to 100 %) of nutrient elements containing polyamines increased the percentage and rate of germination and better growth of pinto bean seedlings by increasing the activity of antioxidant enzymes. Among the treatments studied, the application of 100 mM concentration of nutrient elements containing polyamines under the normal condition and -12 bar drought stress condition caused an increase of 20.69% and 59.26% in seedling dry weight, 15.59% and 28.96% in seedling length vigor index, and 7.46% and 11.73% in the activity of peroxidase enzyme compared to the control, respectively. Conclusion In general, the application of a 100% concentration of nutrient elements containing polyamines had the greatest positive and significant effect on improving seed germination characteristics and biochemical traits of Pinto bean seedlings under drought stress. To investigate the effects of seed-applied nutrient compounds on germination and biochemical characteristics of bean seedlings under polyethylene glycol-induced drought stress, a factorial experiment was conducted in a completely randomized design with three replications. The treatments included drought stress (0, −4, −8, and −12 times) and the application of nutrient compounds containing polyamines (0, 25, 50, 75, and 100 mM). The results showed that drought stress significantly reduced germination rate and percentage to 3.1-6.97%, and reduced seedling dry weight and length to 4.70-28.19%, while increasing the average germination time by about 22.31% compared to the control treatment. However, enriching seeds with nutrient compounds increased seed germination and seedling growth and reduced the average germination time. In the presence and absence of drought stress, the antioxidant enzyme activity and proline content of seedlings obtained from treated seeds were about 3.25 to 4.10 percent higher than those obtained from control seeds. At all levels of drought stress, enriching seeds with different concentrations of nutrient compounds increased germination and improved bean seedling growth by increasing antioxidant enzyme activity. Among the treatments studied, the application of 100 mM nutrient compounds under non-stressed and 12-fold drought stress conditions increased dry weight by 20.69 and 59.26 percent, seedling vigor index by 15.59 and 28.96 percent, and peroxidase enzyme activity by 7.46 and 11.73 percent, respectively, compared to the control treatment, indicating a greater effect of nutrient compounds under drought stress conditions. In general, the application of 100 mM nutrient concentrations had the greatest positive effect on germination, growth, and biochemical traits of seedlings under both favourable and unfavourable conditions. Introduction Drought is one of the most critical environmental stresses limiting crop production worldwide and has adverse effects on germination, emergence, and plant growth and development. In agriculture, drought is defined as the lack of moisture required for normal plant growth and development, and water stress occurs when water loss exceeds water uptake, when water uptake by the plant decreases, or both. The germination and seedling growth stage is one of the most important and decisive stages of plant growth affecting crop production; however, it is strongly influenced by environmental stresses and has therefore been suggested as a suitable criterion for determining plant drought tolerance. Pinto bean (Phaseolus vulgaris L.) is one of the most important grain legumes, playing a major role in the human diet and providing a significant source of protein. Among legumes, the common bean ranks first in terms of cultivated area. This plant is rich in protein, phosphorus, vitamins, and nutrients such as calcium, zinc, copper, iron, manganese, and magnesium, as well as fibre. In addition, due to the symbiosis between atmospheric nitrogen-fixing bacteria and the roots of this plant, it effectively contributes to soil fertility, with large amounts of nitrogen added to cultivated soils each year after harvesting. Several factors can reduce chickpea seed germination and seedling emergence, among which drought stress is one of the most critical. Given that drought stress is one of the most important environmental factors in modern agricultural ecosystems and can significantly reduce plant growth and productivity, preventing or minimizing its harmful effects has long been of interest to researchers. Accordingly, considering the sensitivity of the germination and early growth stages of chickpea seedlings to drought stress, the present study was conducted to investigate the effect of seed application of nutrient compounds containing polyamines on the germination and biochemical characteristics of seedlings of this plant under drought stress. Materials and Methods To investigate the effects of applying nutrient elements containing polyamines on seed germination and the biochemical characteristics of Pinto bean seedlings under polyethylene glycol-induced drought stress, a factorial experiment was conducted in a completely randomized design with three replications. Treatments included drought stress at four levels (0, -4, -8, and -12 bar) and the application of nutrient elements containing polyamines at five levels (0, 25, 50, 75, and 100 %). In this study, the measured traits include germination percentage, germination rate, allometric coefficient, seedling length, seedling dry weight, seedling length vigour index, seedling weight vigour index, and mean germination time (MGT). Also, the activities of the catalase, peroxidase, and polyphenol oxidase enzymes, and the proline content of Pinto bean seedlings were investigated. Statistical analysis was performed using SAS 9.4. Data distribution normality was evaluated using the Kolmogorov-Smirnov test. The comparison of means was performed using Duncan's multiple-range test at the 5% significance level. Excel software was used to draw graphs. Results and Discussion The results showed that drought stress significantly reduced germination rate and percentage, and the dry weight and length of Pinto bean seedlings, and increased the mean time required for germination. However, enriching seeds with nutrient elements containing polyamines increased seed germination and seedling growth, and reduced the mean germination time. Under normal conditions and under drought stress, the activity of antioxidant enzymes and the proline content in seedlings obtained from seeds treated with nutrient elements containing polyamines were higher than in the control. At all levels of drought stress, enrichment of pinto bean seeds with different concentrations (25 to 100 %) of nutrient elements containing polyamines increased the percentage and rate of germination and better growth of pinto bean seedlings by increasing the activity of antioxidant enzymes. Among the treatments studied, the application of 100 mM concentration of nutrient elements containing polyamines under the normal condition and -12 bar drought stress condition caused an increase of 20.69% and 59.26% in seedling dry weight, 15.59% and 28.96% in seedling length vigor index, and 7.46% and 11.73% in the activity of peroxidase enzyme compared to the control, respectively. Conclusion In general, the application of a 100% concentration of nutrient elements containing polyamines had the greatest positive and significant effect on improving seed germination characteristics and biochemical traits of Pinto bean seedlings under drought stress.

https://ijpb.ui.ac.ir/article_30129_47151d8e69ba0e5145e2728d981593db.pdf

University of Isfahan Journal of Plant Biological Sciences 3041-9603 17 3 2025 09 23 The effect of melatonin and copper oxide nanoparticles on drought tolerance in selected wheat cultivars The effect of melatonin and copper oxide nanoparticles on drought tolerance in selected wheat cultivars 25 46 30149 10.22108/ijpb.2025.147187.1425 FA Nafiseh Almasi Department of Biology, Faculty of Sciences, Bu-Ali Sina University, Hamedan, Iran Roya Karamian Department of Biology, Faculty of Sciences, Bu-Ali Sina University, Hamedan, Iran Journal Article 2025 10 24 To study the effects of melatonin and copper oxide nanoparticles on drought stress tolerance in two wheat cultivars (drought-tolerant Sirvan and drought-sensitive Marvdasht), a greenhouse factorial experiment was conducted using a completely randomized design with three replications. The experimental treatments included three irrigation levels (30, 50, and 70% of field capacity), three levels of copper oxide nanoparticles (0, 50, and 100 mg/L), and two levels of melatonin (0 and 100 μM). The results showed that drought stress in both cultivars decreased growth indices, photosynthetic pigment content, and crop yield. Melatonin treatment had a positive effect on leaf area index, relative leaf water content, chlorophyll a and b content, and carotenoids at the 1% level, as well as on crop production indices such as grain number, thousand-grain weight, and biological yield at the 5% level. Additionally, under drought stress conditions, copper oxide nanoparticles improved dry weight, grain number, thousand-grain weight, and photosynthetic pigment content at the 1% level, and leaf area index, relative growth rate, relative water content, and biological yield at the 5% level. Combined treatment with copper oxide nanoparticles and melatonin increased most of the studied indices under drought stress. Therefore, the use of melatonin as a growth regulator and copper oxide nanoparticles as an elicitor can increase wheat tolerance to severe drought stress. Introduction Cereals are the basis of agricultural production in every country, and wheat is of particular importance alongside rice and maize. Wheat (Triticum aestivum L.) is the staple food in many countries worldwide and has a strong influence on food security, the economy, and even political stability. Given the impossibility of a significant increase in cultivated area despite rising consumption demands, the most effective way to increase wheat production is to improve yield; however, drought represents a major constraint to this goal. Therefore, the use of strategies that enhance this strategic crop's resistance to water deficit is of great importance. Melatonin enhances plant defense responses to environmental stresses, particularly by scavenging free radicals. Copper is widely distributed in plant tissues and, as an essential micronutrient, plays a key role in many physiological processes. Numerous studies have reported the positive effects of copper, in the form of conventional salts or nanoparticles, on plant physiological indices, especially under stress conditions. In most field-based selection tests of crops, grain yield alone is considered. To improve the efficiency of breeding programs aimed at developing cultivars adapted to arid and semi-arid regions, reliable indicators of cultivar stability under drought stress, such as grain yield, should be used as selection criteria. Accordingly, in the present study, the performance of two irrigated wheat cultivars (Marvdasht, susceptible to drought, and Sirvan, less sensitive to drought) under drought stress conditions, as well as the effects of melatonin and copper oxide nanoparticles on drought tolerance, were investigated and compared. Material and Methods Seeds of two wheat cultivars, Sirvan and Marvdasht, were obtained from the Karaj Institute of Seed and Seedling Breeding and Production Research and were cultivated in the Plant Physiology Research Greenhouse of Bu-Ali-Sina University. Copper oxide nanoparticle treatment was performed as seed priming before planting them in pots. The pots were irrigated to 70% of the field capacity of soil water by daily weighing until the three-leaf stage of the seedlings. Then, irrigation was applied to induce drought stress at three levels: normal (FC 70%), moderate (FC 50%), and severe (FC 30%). Melatonin was sprayed at a concentration of 100 μM in three stages, with 10-day intervals. Fresh plant samples were used to evaluate growth indices, and frozen samples stored at -80 °C were used to measure biochemical indices. Some important indices, including leaf area, relative water content (RWC), plant dry weight at the end of the vegetative phase, relative growth rate (RGR), grain yield, weight of 1,000 grains, biological yield, and photosynthetic pigment content, were evaluated in two wheat cultivars using conventional methods. Results and Discussion The results indicated that the effects of drought stress on leaf area reduction in the two wheat cultivars, as well as the effects of melatonin and copper oxide nanoparticles, were significant. In fact, the irrigation rate was highly effective in determining plant size, leaf area, and leaf thickness, and under severe drought stress, the leaves became clearly thinner and shorter. Melatonin and copper oxide nanoparticles had a positive effect on leaf relative water content. Drought reduced relative water content in the Sirvan cultivar, whereas melatonin and copper oxide nanoparticles increased it. Drought stress reduced the total plant dry weight at the end of the vegetative phase. Copper oxide nanoparticles and melatonin significantly increased dry weight under drought stress. A significant difference was observed between the two cultivars in relative growth rate, especially under drought stress, and copper oxide nanoparticles and melatonin had a positive effect. The highest grain weight per pot was obtained under regular irrigation with 100 mg/L copper oxide nanoparticles. In contrast, the lowest grain weight was observed in the Marvdasht cultivar under severe drought stress without treatment. Previous studies have shown that thousand-grain weight in wheat plants decreases under drought stress. The use of growth regulators such as melatonin can reduce the destructive effects of water deficit and increase grain yield. Under regular irrigation, the Sirvan cultivar exhibited a lower grain number but a higher grain weight, whereas the Marvdasht cultivar showed a higher grain number and lower grain weight. This difference is often attributed to accelerated ripening and a shorter grain-filling period. The highest thousand-grain weight was observed in the Sirvan cultivar treated with melatonin and copper oxide nanoparticles under regular irrigation. In contrast, the lowest value was observed in the Marvdasht cultivar under severe drought stress. Overall, these effects may be associated with faster ripening and a shorter grain-filling period. In both cultivars under normal irrigation, melatonin and 100 mg/L copper oxide nanoparticles increased plant dry weight. Under stress conditions, the highest plant dry weight was obtained in the presence of melatonin. The results also showed that severe drought significantly reduced photosynthetic pigment content in both cultivars; however, melatonin and copper oxide nanoparticles alleviated the adverse effects of drought. A significant increase in photosynthetic pigments following treatment with copper oxide nanoparticles and melatonin has been reported previously. The enhancement of photosynthesis may be attributed to increased nanoscale copper activity in plants. Conclusion Drought stress negatively affected all the studied indices in both wheat cultivars, leading to significant decreases in various growth indices. By reducing the photosynthetic pigment content, drought stress reduced photosynthesis and, consequently, grain production. The application of melatonin mitigated the negative effects of drought and improved crop production, as indicated by both grain number and grain weight. Copper oxide nanoparticles also had a significant positive effect on most of the studied indicators by alleviating the adverse effects of drought. Moreover, the combined application of copper oxide nanoparticles and melatonin improved most of the studied indicators under drought stress. Although the Sirvan cultivar yielded less than the Marvdasht cultivar under normal irrigation conditions, it performed better under stress. Overall, the effect of melatonin and copper oxide nanoparticles on drought stress tolerance was greater in the Sirvan cultivar than in the Marvdasht cultivar. To study the effects of melatonin and copper oxide nanoparticles on drought stress tolerance in two wheat cultivars (drought-tolerant Sirvan and drought-sensitive Marvdasht), a greenhouse factorial experiment was conducted using a completely randomized design with three replications. The experimental treatments included three irrigation levels (30, 50, and 70% of field capacity), three levels of copper oxide nanoparticles (0, 50, and 100 mg/L), and two levels of melatonin (0 and 100 μM). The results showed that drought stress in both cultivars decreased growth indices, photosynthetic pigment content, and crop yield. Melatonin treatment had a positive effect on leaf area index, relative leaf water content, chlorophyll a and b content, and carotenoids at the 1% level, as well as on crop production indices such as grain number, thousand-grain weight, and biological yield at the 5% level. Additionally, under drought stress conditions, copper oxide nanoparticles improved dry weight, grain number, thousand-grain weight, and photosynthetic pigment content at the 1% level, and leaf area index, relative growth rate, relative water content, and biological yield at the 5% level. Combined treatment with copper oxide nanoparticles and melatonin increased most of the studied indices under drought stress. Therefore, the use of melatonin as a growth regulator and copper oxide nanoparticles as an elicitor can increase wheat tolerance to severe drought stress. Introduction Cereals are the basis of agricultural production in every country, and wheat is of particular importance alongside rice and maize. Wheat (Triticum aestivum L.) is the staple food in many countries worldwide and has a strong influence on food security, the economy, and even political stability. Given the impossibility of a significant increase in cultivated area despite rising consumption demands, the most effective way to increase wheat production is to improve yield; however, drought represents a major constraint to this goal. Therefore, the use of strategies that enhance this strategic crop's resistance to water deficit is of great importance. Melatonin enhances plant defense responses to environmental stresses, particularly by scavenging free radicals. Copper is widely distributed in plant tissues and, as an essential micronutrient, plays a key role in many physiological processes. Numerous studies have reported the positive effects of copper, in the form of conventional salts or nanoparticles, on plant physiological indices, especially under stress conditions. In most field-based selection tests of crops, grain yield alone is considered. To improve the efficiency of breeding programs aimed at developing cultivars adapted to arid and semi-arid regions, reliable indicators of cultivar stability under drought stress, such as grain yield, should be used as selection criteria. Accordingly, in the present study, the performance of two irrigated wheat cultivars (Marvdasht, susceptible to drought, and Sirvan, less sensitive to drought) under drought stress conditions, as well as the effects of melatonin and copper oxide nanoparticles on drought tolerance, were investigated and compared. Material and Methods Seeds of two wheat cultivars, Sirvan and Marvdasht, were obtained from the Karaj Institute of Seed and Seedling Breeding and Production Research and were cultivated in the Plant Physiology Research Greenhouse of Bu-Ali-Sina University. Copper oxide nanoparticle treatment was performed as seed priming before planting them in pots. The pots were irrigated to 70% of the field capacity of soil water by daily weighing until the three-leaf stage of the seedlings. Then, irrigation was applied to induce drought stress at three levels: normal (FC 70%), moderate (FC 50%), and severe (FC 30%). Melatonin was sprayed at a concentration of 100 μM in three stages, with 10-day intervals. Fresh plant samples were used to evaluate growth indices, and frozen samples stored at -80 °C were used to measure biochemical indices. Some important indices, including leaf area, relative water content (RWC), plant dry weight at the end of the vegetative phase, relative growth rate (RGR), grain yield, weight of 1,000 grains, biological yield, and photosynthetic pigment content, were evaluated in two wheat cultivars using conventional methods. Results and Discussion The results indicated that the effects of drought stress on leaf area reduction in the two wheat cultivars, as well as the effects of melatonin and copper oxide nanoparticles, were significant. In fact, the irrigation rate was highly effective in determining plant size, leaf area, and leaf thickness, and under severe drought stress, the leaves became clearly thinner and shorter. Melatonin and copper oxide nanoparticles had a positive effect on leaf relative water content. Drought reduced relative water content in the Sirvan cultivar, whereas melatonin and copper oxide nanoparticles increased it. Drought stress reduced the total plant dry weight at the end of the vegetative phase. Copper oxide nanoparticles and melatonin significantly increased dry weight under drought stress. A significant difference was observed between the two cultivars in relative growth rate, especially under drought stress, and copper oxide nanoparticles and melatonin had a positive effect. The highest grain weight per pot was obtained under regular irrigation with 100 mg/L copper oxide nanoparticles. In contrast, the lowest grain weight was observed in the Marvdasht cultivar under severe drought stress without treatment. Previous studies have shown that thousand-grain weight in wheat plants decreases under drought stress. The use of growth regulators such as melatonin can reduce the destructive effects of water deficit and increase grain yield. Under regular irrigation, the Sirvan cultivar exhibited a lower grain number but a higher grain weight, whereas the Marvdasht cultivar showed a higher grain number and lower grain weight. This difference is often attributed to accelerated ripening and a shorter grain-filling period. The highest thousand-grain weight was observed in the Sirvan cultivar treated with melatonin and copper oxide nanoparticles under regular irrigation. In contrast, the lowest value was observed in the Marvdasht cultivar under severe drought stress. Overall, these effects may be associated with faster ripening and a shorter grain-filling period. In both cultivars under normal irrigation, melatonin and 100 mg/L copper oxide nanoparticles increased plant dry weight. Under stress conditions, the highest plant dry weight was obtained in the presence of melatonin. The results also showed that severe drought significantly reduced photosynthetic pigment content in both cultivars; however, melatonin and copper oxide nanoparticles alleviated the adverse effects of drought. A significant increase in photosynthetic pigments following treatment with copper oxide nanoparticles and melatonin has been reported previously. The enhancement of photosynthesis may be attributed to increased nanoscale copper activity in plants. Conclusion Drought stress negatively affected all the studied indices in both wheat cultivars, leading to significant decreases in various growth indices. By reducing the photosynthetic pigment content, drought stress reduced photosynthesis and, consequently, grain production. The application of melatonin mitigated the negative effects of drought and improved crop production, as indicated by both grain number and grain weight. Copper oxide nanoparticles also had a significant positive effect on most of the studied indicators by alleviating the adverse effects of drought. Moreover, the combined application of copper oxide nanoparticles and melatonin improved most of the studied indicators under drought stress. Although the Sirvan cultivar yielded less than the Marvdasht cultivar under normal irrigation conditions, it performed better under stress. Overall, the effect of melatonin and copper oxide nanoparticles on drought stress tolerance was greater in the Sirvan cultivar than in the Marvdasht cultivar.

https://ijpb.ui.ac.ir/article_30149_5ac64aeba809047c7e5a2457e7def37c.pdf

University of Isfahan Journal of Plant Biological Sciences 3041-9603 17 3 2025 09 23 Effect of LED Light Spectra and Rhizobium rhizogenes Strains on the Growth and Physiological Characteristics of German Chamomile (Matrocaria chamomilla L.) Effect of LED Light Spectra and Rhizobium rhizogenes Strains on the Growth and Physiological Characteristics of German Chamomile (Matrocaria chamomilla L.) 47 66 29929 10.22108/ijpb.2025.144603.1402 FA Nastaran Maham Department of Horticultural Sciences, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran Esmaeil Chamani Department of Horticultural Sciences, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran Mehdi Mohebodini Department of Horticultural Sciences, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran Asghar Estaji Department of Horticultural Sciences, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran Roza Shahbazi Department of Horticultural Sciences, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran Journal Article 2025 03 11 This study investigated the individual and combined effects of LED light spectra and Rhizobium rhizogenes strains on the growth and physiological attributes of German chamomile (Matricaria chamomilla L.). A factorial experiment with three replications was conducted under controlled conditions. Plantlets inoculated with bacterial strains A4 or ATCC15834 were exposed to seven light regimes: monochromatic white (W100), red (R100), blue (B100), and red–blue combinations (R80B20, R60B40, R40B60, R20B80). The interaction between the bacterial strain and the light spectrum significantly affected most of the measured parameters. The A4 strain under red light (R100) produced the longest shoots (19.5 mm), whereas ATCC15834, combined with R40B60, generated the longest roots (90.9 mm). Maximum shoot and root fresh weights (2342 and 3887 mg, respectively) were obtained from A4 under R20B80 light. From a physiological perspective, A4 under R80B20 light resulted in the highest chlorophyll a content, while ATCC15834 under R40B60 produced the greatest chlorophyll b and carotenoid levels (21.26 mg g-1 FW). The R60B40 spectrum enhanced flavonoid biosynthesis, and A4 under R100 exhibited the strongest antioxidant activity (14.71% DPPH inhibition). These findings demonstrate that combining specific bacterial strains with optimized light spectra can significantly enhance chamomile growth and its medicinal value. Introduction German chamomile, a member of the Asteraceae family, is a well-known medicinal herb valued for its essential oils and flavonoids, which possess antioxidant, anti-inflammatory, and antimicrobial properties. However, sustainable production faces challenges due to agricultural limitations and overexploitation. In vitro culture, integrated with elicitor-based strategies, offers an effective means to conserve germplasm and enhance bioactive metabolite production. Among elicitors, Light-Emitting Diodes (LEDs) enable precise spectral manipulation, with red and blue wavelengths particularly efficient at regulating photosynthesis and secondary metabolism. Similarly, Rhizobium rhizogenes acts as a biological elicitor, stimulating root induction and enhancing metabolite accumulation through phytohormonal interactions. This research aimed to explore the synergistic influence of LED spectra and R. rhizogenes strains on morpho-physiological traits and secondary metabolite biosynthesis in German chamomile. Materials and Methods The experiment was performed during 2022–2023 in the tissue culture laboratory of the University of Mohaghegh Ardabili, Iran. Chamomile seeds were surface-sterilised using liquid soap, 70% ethanol, and 3% sodium hypochlorite, then rinsed with sterile distilled water. Sterilized seeds were germinated on solid MS medium. After eight weeks, uniform seedlings were inoculated at the crown with R. rhizogenes strains A4 or ATCC15834. Following 48 hours of co-cultivation in darkness, plantlets were transferred to MS medium supplemented with 500 mg L-1 cefotaxime. They were subsequently exposed toseven LED treatments (90 µmol m-2 s-1) for 6 weeks. Growth and physiological parameters were recorded, and data were analyzed by factorial ANOVA followed by Duncan’s test (P ≤ 0.01). Results and Discussion Analysis of variance revealed that the interaction between LED light spectra and Rhizobium rhizogenes strains significantly (P ≤ 0.01) influenced the morpho-physiological profile of German chamomile plantlets. Morphological Development The evaluation of growth parameters revealed that the most significant synergy for biomass accumulation was observed between the A4 bacterial strain and the R20B80 light regime. This specific combination yielded the highest shoot fresh weight (2342 mg), underscoring its superior efficacy in enhancing aerial biomass production. Secondary Metabolite Production The production of pharmaceutically valuable secondary metabolites was markedly affected by the treatments. The synthesis of total phenolics exhibited a complex, spectrum-dependent pattern. The R20B80 treatment, when combined with bacterial inoculation, resulted in a significant increase in phenolic content compared to the non-inoculated control under the same light, indicating an apparent bacterial elicitation effect under this specific spectrum. Antioxidant Capacity The antioxidant capacity, a critical functional property derived from secondary metabolites, was most potently enhanced in plantlets inoculated with the A4 strain and cultivated under monochromatic red light (R100), resulting in the highest DPPH radical scavenging activity (14.71% inhibition). This confirms that the A4 strain and red light are the most effective combination for enhancing the plant's functional antioxidant defense. In summary, this study demonstrates that the strategic combination of LED light spectra and specific bacterial strains can effectively steer both the growth and the metabolic profile of German chamomile. The A4 strain, particularly under the R20B80 spectrum, proved highly effective at enhancing biomass and phenolic content, while its combination with red light (R100) optimally boosted antioxidant capacity. Conclusion This study demonstrates that tailored combinations of LED light spectra and R. rhizogenes strains, particularly the A4 strain with R20B80 and R100 light, can simultaneously enhance growth and the production of valuable bioactive compounds in German chamomile. This approach provides a sustainable strategy for optimizing the pharmaceutical quality of chamomile under controlled conditions. This study investigated the individual and combined effects of LED light spectra and Rhizobium rhizogenes strains on the growth and physiological attributes of German chamomile (Matricaria chamomilla L.). A factorial experiment with three replications was conducted under controlled conditions. Plantlets inoculated with bacterial strains A4 or ATCC15834 were exposed to seven light regimes: monochromatic white (W100), red (R100), blue (B100), and red–blue combinations (R80B20, R60B40, R40B60, R20B80). The interaction between the bacterial strain and the light spectrum significantly affected most of the measured parameters. The A4 strain under red light (R100) produced the longest shoots (19.5 mm), whereas ATCC15834, combined with R40B60, generated the longest roots (90.9 mm). Maximum shoot and root fresh weights (2342 and 3887 mg, respectively) were obtained from A4 under R20B80 light. From a physiological perspective, A4 under R80B20 light resulted in the highest chlorophyll a content, while ATCC15834 under R40B60 produced the greatest chlorophyll b and carotenoid levels (21.26 mg g-1 FW). The R60B40 spectrum enhanced flavonoid biosynthesis, and A4 under R100 exhibited the strongest antioxidant activity (14.71% DPPH inhibition). These findings demonstrate that combining specific bacterial strains with optimized light spectra can significantly enhance chamomile growth and its medicinal value. Introduction German chamomile, a member of the Asteraceae family, is a well-known medicinal herb valued for its essential oils and flavonoids, which possess antioxidant, anti-inflammatory, and antimicrobial properties. However, sustainable production faces challenges due to agricultural limitations and overexploitation. In vitro culture, integrated with elicitor-based strategies, offers an effective means to conserve germplasm and enhance bioactive metabolite production. Among elicitors, Light-Emitting Diodes (LEDs) enable precise spectral manipulation, with red and blue wavelengths particularly efficient at regulating photosynthesis and secondary metabolism. Similarly, Rhizobium rhizogenes acts as a biological elicitor, stimulating root induction and enhancing metabolite accumulation through phytohormonal interactions. This research aimed to explore the synergistic influence of LED spectra and R. rhizogenes strains on morpho-physiological traits and secondary metabolite biosynthesis in German chamomile. Materials and Methods The experiment was performed during 2022–2023 in the tissue culture laboratory of the University of Mohaghegh Ardabili, Iran. Chamomile seeds were surface-sterilised using liquid soap, 70% ethanol, and 3% sodium hypochlorite, then rinsed with sterile distilled water. Sterilized seeds were germinated on solid MS medium. After eight weeks, uniform seedlings were inoculated at the crown with R. rhizogenes strains A4 or ATCC15834. Following 48 hours of co-cultivation in darkness, plantlets were transferred to MS medium supplemented with 500 mg L-1 cefotaxime. They were subsequently exposed toseven LED treatments (90 µmol m-2 s-1) for 6 weeks. Growth and physiological parameters were recorded, and data were analyzed by factorial ANOVA followed by Duncan’s test (P ≤ 0.01). Results and Discussion Analysis of variance revealed that the interaction between LED light spectra and Rhizobium rhizogenes strains significantly (P ≤ 0.01) influenced the morpho-physiological profile of German chamomile plantlets. Morphological Development The evaluation of growth parameters revealed that the most significant synergy for biomass accumulation was observed between the A4 bacterial strain and the R20B80 light regime. This specific combination yielded the highest shoot fresh weight (2342 mg), underscoring its superior efficacy in enhancing aerial biomass production. Secondary Metabolite Production The production of pharmaceutically valuable secondary metabolites was markedly affected by the treatments. The synthesis of total phenolics exhibited a complex, spectrum-dependent pattern. The R20B80 treatment, when combined with bacterial inoculation, resulted in a significant increase in phenolic content compared to the non-inoculated control under the same light, indicating an apparent bacterial elicitation effect under this specific spectrum. Antioxidant Capacity The antioxidant capacity, a critical functional property derived from secondary metabolites, was most potently enhanced in plantlets inoculated with the A4 strain and cultivated under monochromatic red light (R100), resulting in the highest DPPH radical scavenging activity (14.71% inhibition). This confirms that the A4 strain and red light are the most effective combination for enhancing the plant's functional antioxidant defense. In summary, this study demonstrates that the strategic combination of LED light spectra and specific bacterial strains can effectively steer both the growth and the metabolic profile of German chamomile. The A4 strain, particularly under the R20B80 spectrum, proved highly effective at enhancing biomass and phenolic content, while its combination with red light (R100) optimally boosted antioxidant capacity. Conclusion This study demonstrates that tailored combinations of LED light spectra and R. rhizogenes strains, particularly the A4 strain with R20B80 and R100 light, can simultaneously enhance growth and the production of valuable bioactive compounds in German chamomile. This approach provides a sustainable strategy for optimizing the pharmaceutical quality of chamomile under controlled conditions.

https://ijpb.ui.ac.ir/article_29929_9ba0ace21e45e57aea0c337f243e7899.pdf

University of Isfahan Journal of Plant Biological Sciences 3041-9603 17 3 2025 09 23 The impact of nitrogen concentration on the physiological responses of rice seedlings after inoculation with Azospirillum brasilence The impact of nitrogen concentration on the physiological responses of rice seedlings after inoculation with Azospirillum brasilence 67 88 30080 10.22108/ijpb.2025.146865.1423 FA Mohammad Noori 1Department of Biology-Plant Physiology, Faculty of Science, Golestan University, Gorgan, Iran Mahnaz Aghdasi 1Department of Biology-Plant Physiology, Faculty of Science, Golestan University, Gorgan, Iran Mohammad Hossein Arzanesh Department of Soil and Water Research, Golestan's Agricultural and Natural Resources Research Center, Gorgan, Iran Journal Article 2025 09 30 Azospirillum is one of the most important plant growth-promoting bacteria, with the ability to fix nitrogen. The current study aimed to investigate the physiological responses of rice plants with different nitrogen concentrations when inoculated with Azospirillum brasilense. In this experiment, the growth and physiological responses of 21-day-old rice seedlings (Oryza sativa L., cv. Hashemi) were investigated after 4 weeks of treatment with different nitrogen levels, including complete nitrogen (N), half (N/2), fourth (N/4), and zero nitrogen (control) concentrations under two inoculated (AB) and non-inoculated (NI) conditions. The experiment was conducted in a completely randomized design with 4 replications. The current data showed that nitrogen concentration significantly affects all measured parameters in both AB and NI plants. The highest values of growth traits, biomass accumulation, photosynthetic pigments, soluble sugars, and antioxidant enzyme activities (catalase and peroxidase) were observed in plants treated with full nitrogen and inoculated with A. brasilense. These findings highlight the potential of A. brasilense to enhance nitrogen efficiency in agricultural crops. Meanwhile, our data showed that inoculation with A. brasilense can improve rice plant productivity, especially under optimal nitrogen conditions. Introduction Rice (Oryza sativa) is a monocotyledonous plant that belongs to the Poaceae family. Rice is a strategic crop and the primary food source for more than half of the world’s population. The increase in rice cultivation areas in our country and the widespread use of chemical fertilizers have led to the emergence of various diseases. Today, the use of Plant Growth Promoting Rhizobacteria (PGPR) is considered an alternative to chemical fertilizers. These bacteria are present in the rhizosphere of plants and enhance plant growth in various ways, including increasing nutrient absorption, producing plant hormones, and protecting plants against pathogens. These bacteria enhance mineral nutrient uptake by stimulating root system development. A group of PGPRs is called endophytes. Endophytes are non-pathogenic bacteria that spend part of their life cycle within plant tissues. So far, various types of nitrogen-fixing endophytes have been identified and reported in the stems, roots, and seeds of rice. Azospirillum is one of the most important plant growth-promoting bacteria, capable of fixing nitrogen. Recently, this bacterium has been used as a biofertilizer, especially in areas facing nitrogen deficiency. By fixing atmospheric nitrogen and converting it into a usable form, Azospirillum brasilense improves nitrogen efficiency and reduces demand for chemical fertilizers. The current study aimed to investigate the physiological responses of rice seedlings to different nitrogen concentrations when inoculated with Azospirillum brasilense. Methods and Materials In this experiment, Azospirillum brasilense was prepared from the Soil Biology Laboratory of the Agricultural Research and Education Center of Golestan province. Then, the bacteria were cultured and identified on a specific RC medium. After selecting a single colony of the desired bacteria, the bacteria were cultured on NFB liquid medium at 30 °C for 48 hours. Rice seeds of the Hashemi cultivar were obtained from the National Rice Research Institute (AML). After surface sterilization, the seeds were placed on moist filter paper at 29 °C for germination. Then, the 7-day-old seedlings were transferred to Yoshida culture medium under a photoperiod of 18 h day (33 °C) and 6 h night (22 °C), with a relative humidity of 71%. In the next step, 21-day-old rice seedlings were treated with Yoshida medium containing nitrogen levels: complete nitrogen (N), half nitrogen (N/2), quarter nitrogen (N/4), and zero nitrogen (control) under two inoculation conditions: inoculated (AB) and non-inoculated (NI). After 4 weeks of treatment, the roots of rice seedlings were collected, and various growth parameters and several biochemical factors were examined. The experiment was conducted in a completely randomized design with four replications. Results and Discussion Microscopic observations revealed that the bacteria first settled on the root epidermis and then entered the root cells. After passing through the epidermis, the bacteria penetrated the parenchyma layer and formed colonies. The results showed that small and large colonies, with single or scattered bacteria, were observed in the root cells. On the other hand, the current data showed that nitrogen concentration significantly affects all measured parameters in both AB and NI plants. The highest amount of root and shoot length, root fresh and dry weight, shoot dry weight, total dry and fresh weight, relative growth, soluble and total shoot sugar, chlorophyll b, and total chlorophyll were observed in the treatment with both full nitrogen concentration and inoculation with A. brasilense. Also, the present data revealed that seedlings inoculated with Azospirillum performed better than the non-inoculated samples.Meanwhile, current data showed that catalase enzyme activity increased with increased nitrogen concentration (in both inoculated and non-inoculated conditions). However, catalase enzyme activity was higher in inoculated seedlings at all nitrogen levels, compared to non-inoculated seedlings. These data indicate that inoculation with A. brasilense increases oxidative stress tolerance in rice seedlings. This evidence suggests that this bacterium improves plant resilience to treatment with different nitrogen concentrations and enhances their ability to scavenge reactive oxygen species (ROS) produced during nitrogen metabolism. The present data showed that peroxidase enzyme activity increased with higher nitrogen concentrations, in both inoculated and non-inoculated conditions. Conclusion The present results showed that inoculating rice seedlings with A. brasilense can significantly enhance their physiological responses. At all nitrogen concentrations, treatment improved the growth of inoculated plants, which showed higher protein content and enzyme activity compared to non-inoculated seedlings. These findings highlight the potential of A. brasilense to enhance nitrogen efficiency in crops. Meanwhile, our data showed that inoculation with A. brasilense can improve rice seedling productivity, especially under optimal nitrogen conditions. Azospirillum is one of the most important plant growth-promoting bacteria, with the ability to fix nitrogen. The current study aimed to investigate the physiological responses of rice plants with different nitrogen concentrations when inoculated with Azospirillum brasilense. In this experiment, the growth and physiological responses of 21-day-old rice seedlings (Oryza sativa L., cv. Hashemi) were investigated after 4 weeks of treatment with different nitrogen levels, including complete nitrogen (N), half (N/2), fourth (N/4), and zero nitrogen (control) concentrations under two inoculated (AB) and non-inoculated (NI) conditions. The experiment was conducted in a completely randomized design with 4 replications. The current data showed that nitrogen concentration significantly affects all measured parameters in both AB and NI plants. The highest values of growth traits, biomass accumulation, photosynthetic pigments, soluble sugars, and antioxidant enzyme activities (catalase and peroxidase) were observed in plants treated with full nitrogen and inoculated with A. brasilense. These findings highlight the potential of A. brasilense to enhance nitrogen efficiency in agricultural crops. Meanwhile, our data showed that inoculation with A. brasilense can improve rice plant productivity, especially under optimal nitrogen conditions. Introduction Rice (Oryza sativa) is a monocotyledonous plant that belongs to the Poaceae family. Rice is a strategic crop and the primary food source for more than half of the world’s population. The increase in rice cultivation areas in our country and the widespread use of chemical fertilizers have led to the emergence of various diseases. Today, the use of Plant Growth Promoting Rhizobacteria (PGPR) is considered an alternative to chemical fertilizers. These bacteria are present in the rhizosphere of plants and enhance plant growth in various ways, including increasing nutrient absorption, producing plant hormones, and protecting plants against pathogens. These bacteria enhance mineral nutrient uptake by stimulating root system development. A group of PGPRs is called endophytes. Endophytes are non-pathogenic bacteria that spend part of their life cycle within plant tissues. So far, various types of nitrogen-fixing endophytes have been identified and reported in the stems, roots, and seeds of rice. Azospirillum is one of the most important plant growth-promoting bacteria, capable of fixing nitrogen. Recently, this bacterium has been used as a biofertilizer, especially in areas facing nitrogen deficiency. By fixing atmospheric nitrogen and converting it into a usable form, Azospirillum brasilense improves nitrogen efficiency and reduces demand for chemical fertilizers. The current study aimed to investigate the physiological responses of rice seedlings to different nitrogen concentrations when inoculated with Azospirillum brasilense. Methods and Materials In this experiment, Azospirillum brasilense was prepared from the Soil Biology Laboratory of the Agricultural Research and Education Center of Golestan province. Then, the bacteria were cultured and identified on a specific RC medium. After selecting a single colony of the desired bacteria, the bacteria were cultured on NFB liquid medium at 30 °C for 48 hours. Rice seeds of the Hashemi cultivar were obtained from the National Rice Research Institute (AML). After surface sterilization, the seeds were placed on moist filter paper at 29 °C for germination. Then, the 7-day-old seedlings were transferred to Yoshida culture medium under a photoperiod of 18 h day (33 °C) and 6 h night (22 °C), with a relative humidity of 71%. In the next step, 21-day-old rice seedlings were treated with Yoshida medium containing nitrogen levels: complete nitrogen (N), half nitrogen (N/2), quarter nitrogen (N/4), and zero nitrogen (control) under two inoculation conditions: inoculated (AB) and non-inoculated (NI). After 4 weeks of treatment, the roots of rice seedlings were collected, and various growth parameters and several biochemical factors were examined. The experiment was conducted in a completely randomized design with four replications. Results and Discussion Microscopic observations revealed that the bacteria first settled on the root epidermis and then entered the root cells. After passing through the epidermis, the bacteria penetrated the parenchyma layer and formed colonies. The results showed that small and large colonies, with single or scattered bacteria, were observed in the root cells. On the other hand, the current data showed that nitrogen concentration significantly affects all measured parameters in both AB and NI plants. The highest amount of root and shoot length, root fresh and dry weight, shoot dry weight, total dry and fresh weight, relative growth, soluble and total shoot sugar, chlorophyll b, and total chlorophyll were observed in the treatment with both full nitrogen concentration and inoculation with A. brasilense. Also, the present data revealed that seedlings inoculated with Azospirillum performed better than the non-inoculated samples.Meanwhile, current data showed that catalase enzyme activity increased with increased nitrogen concentration (in both inoculated and non-inoculated conditions). However, catalase enzyme activity was higher in inoculated seedlings at all nitrogen levels, compared to non-inoculated seedlings. These data indicate that inoculation with A. brasilense increases oxidative stress tolerance in rice seedlings. This evidence suggests that this bacterium improves plant resilience to treatment with different nitrogen concentrations and enhances their ability to scavenge reactive oxygen species (ROS) produced during nitrogen metabolism. The present data showed that peroxidase enzyme activity increased with higher nitrogen concentrations, in both inoculated and non-inoculated conditions. Conclusion The present results showed that inoculating rice seedlings with A. brasilense can significantly enhance their physiological responses. At all nitrogen concentrations, treatment improved the growth of inoculated plants, which showed higher protein content and enzyme activity compared to non-inoculated seedlings. These findings highlight the potential of A. brasilense to enhance nitrogen efficiency in crops. Meanwhile, our data showed that inoculation with A. brasilense can improve rice seedling productivity, especially under optimal nitrogen conditions.

https://ijpb.ui.ac.ir/article_30080_ab4eb2901709d8feca9690e177663c40.pdf

University of Isfahan Journal of Plant Biological Sciences 3041-9603 17 3 2025 09 23 Effect of polyvinyl chloride microplastics and water deficit stress on leaf greenness and antioxidant activity of maize seedlings mediated by Piriformospora indica Effect of polyvinyl chloride microplastics and water deficit stress on leaf greenness and antioxidant activity of maize seedlings mediated by Piriformospora indica 89 108 30282 10.22108/ijpb.2026.147945.1432 FA Maryam Saman Department of Agriculture, Faculty of Technical and Engineering, Payame Noor University, Tehran, Iran. Ali Sepehri Department of Plant Production and Genetics, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran Journal Article 2025 12 30 Given the increasing contamination of agricultural soils with microplastics and the concurrent rise in water scarcity, this study investigated the effects of symbiosis with Piriformospora indica on the physiological and biochemical parameters of maize seedlings exposed to polyvinyl chloride microplastics under water deficit stress. The experiment was carried out as a factorial based on a completely randomized design with three levels of microplastic (0, 0.1, and 1%), two levels of fungus (inoculation and non-inoculation), and three levels of water deficit stress (100, 75, and 50% of field capacity). The results showed that in plants exposed to 1% microplastic, the activities of superoxide dismutase, catalase, and peroxidase increased significantly, similar to water deficit stress. The levels of hydrogen peroxide and malondialdehyde, as well as membrane damage, in maize seedlings exposed to stress, also increased compared to the control. Inoculation with the fungus improved antioxidant enzyme activity, such that the activities of superoxide dismutase, catalase, and peroxidase in inoculated plants under the highest water deficit stress and in the presence of 1% microplastic were (65.9 and 57.2), (47.1 and 40.2), and (61.3 and 69.3) percent higher than in non-inoculated plants, respectively. Furthermore, the presence of the fungus reduced malondialdehyde and hydrogen peroxide levels, as well as electrolyte leakage, in stressed plants. Overall, the results showed that P. indica improved the growth and dry matter production of maize seedlings exposed to microplastic particle toxicity and water deficit stress by enhancing antioxidant defence and increasing the leaf greenness index. Introduction In recent years, crop plants have been increasingly exposed to various environmental stresses and emerging contaminants, such as microplastics, which threaten their growth, yield, and overall agricultural sustainability (Illanese et al., 2025). Among abiotic stresses, water deficit stress is a major constraint that limits transpiration and CO₂ uptake through stomatal closure, thereby reducing biomass accumulation and productivity (Xu et al., 2022). Water deficit stress also triggers the excessive generation of reactive oxygen species (ROS), leading to oxidative stress, membrane damage, ion imbalance, and reduced photosynthetic efficiency (Zia et al., 2021). Simultaneously, contamination of agricultural soils with microplastics has become a growing global concern (Hasan & Tarannum, 2025). These particles can abrade root surfaces and disrupt water and nutrient uptake, ultimately inhibiting plant growth (Hartmann et al., 2022). Similar to drought, microplastic exposure induces ROS overproduction and oxidative stress, which compromise cellular integrity and metabolism (Gan et al., 2023). In this context, the utilization of beneficial plant–microbe interactions has gained increasing attention as an eco-friendly and effective strategy to alleviate the adverse effects of environmental stresses on plants (Boorboori et al., 2022). Piriformospora indica, a root endophytic fungus, is known for its ability to colonize a wide range of monocot and dicot plants (Jangir et al., 2021). Symbiosis between plants and P. indica enhances stress tolerance by activating the plant defence system, upregulating stress-related genes, and boosting antioxidant enzyme activity, thereby improving the plant’s resilience to adverse environmental conditions (Li et al., 2023). Considering the simultaneous occurrence of water deficit stress and microplastic contamination in agricultural ecosystems, it is essential to explore their combined impact on plant physiology. Therefore, this study investigates the influence of P. indica symbiosis on key physiological and biochemical traits of maize (Zea mays) seedlings exposed to polyvinyl chloride (PVC) microplastics under a water-deficit stress condition. Materials and Methods This experiment was conducted using a completely randomized factorial design with three replications in 2023 in the research greenhouse of Bu-Ali Sina University, Hamadan, Iran. The experimental factors comprised polyvinyl chloride (PVC) microplastics at three levels (0, 0.1, and 1% of soil weight), Piriformospora indica inoculation at two levels (inoculated and non-inoculated), and water deficit stress at three levels (no stress, moderate, and severe stress, respectively, equivalent to irrigation at 100, 75, and 50% of field capacity). Water deficit stress was initiated 14 days after sowing. Thirty days after sowing, the leaf chlorophyll content (SPAD index) was measured. Fresh leaf samples were collected for biochemical analyses, while shoot and root samples were oven-dried to determine dry biomass. To evaluate root colonization by P. indica, 1-cm-long root segments were carefully washed, stained, and observed under a light microscope to calculate the percentage of colonization. Antioxidant enzyme activities, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), as well as malondialdehyde (MDA) content and electrolyte leakage, were determined using fresh leaf samples. Data were statistically analyzed using SAS software (version 9.4) after confirming the normality of residuals. Treatment means were compared using the least significant difference (LSD) test at a 5% probability level. Graphs were prepared using Microsoft Excel. Results and Discussion The results demonstrated that P. indica fungus successfully colonized plant roots under all experimental conditions. In unstressed plants, the root colonization rate was 89%, whereas in plants exposed to 50% field capacity and 1% microplastic contamination, it was approximately 40%. Stress induced by PVC microplastic particles and reduced soil moisture led to higher hydrogen peroxide accumulation and membrane damage in maize seedlings, resulting in a decline in leaf greenness and overall growth. Inoculation with P. indica significantly enhanced the activity of antioxidant enzymes, including SOD, CAT, and POD. This enhanced enzymatic activity reflects the protective role of P. indica in mitigating oxidative stress, as evidenced by reduced malondialdehyde and hydrogen peroxide contents and lower electrolyte leakage in inoculated plants under stress. Moreover, symbiosis with P. indica contributed to chlorophyll preservation, higher leaf greenness, and greater biomass accumulation. For example, the dry weight of inoculated plants under severe water deficit and 1% microplastic stress was on average 45.8% higher than that of uninoculated controls. Overall, these findings suggest that the symbiotic association between P. indica and crop plants can serve as an effective biological strategy to alleviate the adverse effects of microplastic toxicity and improve plant resilience and productivity under water-deficit conditions. Given the increasing contamination of agricultural soils with microplastics and the concurrent rise in water scarcity, this study investigated the effects of symbiosis with Piriformospora indica on the physiological and biochemical parameters of maize seedlings exposed to polyvinyl chloride microplastics under water deficit stress. The experiment was carried out as a factorial based on a completely randomized design with three levels of microplastic (0, 0.1, and 1%), two levels of fungus (inoculation and non-inoculation), and three levels of water deficit stress (100, 75, and 50% of field capacity). The results showed that in plants exposed to 1% microplastic, the activities of superoxide dismutase, catalase, and peroxidase increased significantly, similar to water deficit stress. The levels of hydrogen peroxide and malondialdehyde, as well as membrane damage, in maize seedlings exposed to stress, also increased compared to the control. Inoculation with the fungus improved antioxidant enzyme activity, such that the activities of superoxide dismutase, catalase, and peroxidase in inoculated plants under the highest water deficit stress and in the presence of 1% microplastic were (65.9 and 57.2), (47.1 and 40.2), and (61.3 and 69.3) percent higher than in non-inoculated plants, respectively. Furthermore, the presence of the fungus reduced malondialdehyde and hydrogen peroxide levels, as well as electrolyte leakage, in stressed plants. Overall, the results showed that P. indica improved the growth and dry matter production of maize seedlings exposed to microplastic particle toxicity and water deficit stress by enhancing antioxidant defence and increasing the leaf greenness index. Introduction In recent years, crop plants have been increasingly exposed to various environmental stresses and emerging contaminants, such as microplastics, which threaten their growth, yield, and overall agricultural sustainability (Illanese et al., 2025). Among abiotic stresses, water deficit stress is a major constraint that limits transpiration and CO₂ uptake through stomatal closure, thereby reducing biomass accumulation and productivity (Xu et al., 2022). Water deficit stress also triggers the excessive generation of reactive oxygen species (ROS), leading to oxidative stress, membrane damage, ion imbalance, and reduced photosynthetic efficiency (Zia et al., 2021). Simultaneously, contamination of agricultural soils with microplastics has become a growing global concern (Hasan & Tarannum, 2025). These particles can abrade root surfaces and disrupt water and nutrient uptake, ultimately inhibiting plant growth (Hartmann et al., 2022). Similar to drought, microplastic exposure induces ROS overproduction and oxidative stress, which compromise cellular integrity and metabolism (Gan et al., 2023). In this context, the utilization of beneficial plant–microbe interactions has gained increasing attention as an eco-friendly and effective strategy to alleviate the adverse effects of environmental stresses on plants (Boorboori et al., 2022). Piriformospora indica, a root endophytic fungus, is known for its ability to colonize a wide range of monocot and dicot plants (Jangir et al., 2021). Symbiosis between plants and P. indica enhances stress tolerance by activating the plant defence system, upregulating stress-related genes, and boosting antioxidant enzyme activity, thereby improving the plant’s resilience to adverse environmental conditions (Li et al., 2023). Considering the simultaneous occurrence of water deficit stress and microplastic contamination in agricultural ecosystems, it is essential to explore their combined impact on plant physiology. Therefore, this study investigates the influence of P. indica symbiosis on key physiological and biochemical traits of maize (Zea mays) seedlings exposed to polyvinyl chloride (PVC) microplastics under a water-deficit stress condition. Materials and Methods This experiment was conducted using a completely randomized factorial design with three replications in 2023 in the research greenhouse of Bu-Ali Sina University, Hamadan, Iran. The experimental factors comprised polyvinyl chloride (PVC) microplastics at three levels (0, 0.1, and 1% of soil weight), Piriformospora indica inoculation at two levels (inoculated and non-inoculated), and water deficit stress at three levels (no stress, moderate, and severe stress, respectively, equivalent to irrigation at 100, 75, and 50% of field capacity). Water deficit stress was initiated 14 days after sowing. Thirty days after sowing, the leaf chlorophyll content (SPAD index) was measured. Fresh leaf samples were collected for biochemical analyses, while shoot and root samples were oven-dried to determine dry biomass. To evaluate root colonization by P. indica, 1-cm-long root segments were carefully washed, stained, and observed under a light microscope to calculate the percentage of colonization. Antioxidant enzyme activities, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), as well as malondialdehyde (MDA) content and electrolyte leakage, were determined using fresh leaf samples. Data were statistically analyzed using SAS software (version 9.4) after confirming the normality of residuals. Treatment means were compared using the least significant difference (LSD) test at a 5% probability level. Graphs were prepared using Microsoft Excel. Results and Discussion The results demonstrated that P. indica fungus successfully colonized plant roots under all experimental conditions. In unstressed plants, the root colonization rate was 89%, whereas in plants exposed to 50% field capacity and 1% microplastic contamination, it was approximately 40%. Stress induced by PVC microplastic particles and reduced soil moisture led to higher hydrogen peroxide accumulation and membrane damage in maize seedlings, resulting in a decline in leaf greenness and overall growth. Inoculation with P. indica significantly enhanced the activity of antioxidant enzymes, including SOD, CAT, and POD. This enhanced enzymatic activity reflects the protective role of P. indica in mitigating oxidative stress, as evidenced by reduced malondialdehyde and hydrogen peroxide contents and lower electrolyte leakage in inoculated plants under stress. Moreover, symbiosis with P. indica contributed to chlorophyll preservation, higher leaf greenness, and greater biomass accumulation. For example, the dry weight of inoculated plants under severe water deficit and 1% microplastic stress was on average 45.8% higher than that of uninoculated controls. Overall, these findings suggest that the symbiotic association between P. indica and crop plants can serve as an effective biological strategy to alleviate the adverse effects of microplastic toxicity and improve plant resilience and productivity under water-deficit conditions.

https://ijpb.ui.ac.ir/article_30282_7ec0c30856695272c84f080ca7a5559c.pdf