نوع مقاله : مقاله پژوهشی
عنوان مقاله English
نویسنده English
Introduction: Among the environmental stresses, drought is one of the most important factors affecting the growth and development of plants, and due to the simultaneous effect on the morphological, physiological, and biochemical characteristics of plant tissues and cells, it ultimately leads to plant growth decay and yield reduction. This stress induces various physiological, biochemical, and molecular responses in plants as a survival mechanism. Also, this stress can reduce the chlorophyll content, relative water content, stomatal conductance, and ultimately grain yield. The results of some studies show that increasing the concentration of CO₂ in the leaves leads to a reduction of the negative effects caused by drought stress in plants. One of the important strategies to increase the concentration of CO₂ in plants is the use of compounds such as methanol, which can increase the concentration of CO₂ in plants and help photosynthesis and growth under drought stress conditions. In this case, methanol can act as an additional carbon source, and in environmental conditions where the plant is limited by CO₂ (such as drought stress), methanol as a precursor can help the plant absorb more carbon and turn it into the final product of photosynthesis. Therefore, the aim of this study was to investigate the effect of methanol foliar spraying on some physiological reactions of cowpea plants in the face of drought stress.
Materials and Methods: The research was conducted as a split-plot experiment based on a randomized complete block design with three replications during the summer of 2021 in the Dezful region. Drought stress was applied based on irrigation intervals at four levels (80, 110, 140, and 170 mm of evaporation from a Class A evaporation pan) as the main factor. Foliar spraying was performed at four levels (0, 10, 20, and 30% volumetric methanol solution with 2 grams per liter of glycine) as the sub-factor. The evaluated traits included stomatal conductance, transpiration, sub-stomatal CO2 concentration, photosynthesis, relative water content, chlorophyll index, proline content, electrolyte leakage, anthocyanin, and flavonoid. Analysis of variance was performed using Statistical Analysis System (SAS version: 9.3). The means were compared using Duncan's multiple range test at 5% probability level.
Results and Discussion: The results of the experiment showed that under drought stress conditions, stomatal conductance, transpiration rate, sub-stomatal CO2 concentration, photosynthetic rate, relative water content, and chlorophyll index decreased. In contrast, the content of proline, electrolyte leakage, anthocyanins, and flavonoids increased. Methanol foliar application also had a significant effect on all the studied traits, with the maximum effect observed in the treatment with 30% volumetric methanol solution, particularly on transpiration rate and anthocyanin content. Under irrigation conditions after 170 mm of evaporation, foliar application with 30% volumetric methanol resulted in a significant increase in stomatal conductance (89%), sub-stomatal CO2 concentration (20%), photosynthetic rate (67%), and chlorophyll index (31%), anthocyanin content (12%) as well as a 27% reduction in the amount of electrolytes leakage compared to the treatment of no foliar application (control) was observed in these conditions.
Conclusion: Based on the results of this study, the use of methanol, especially the foliar spraying of 30% volumetric of methanol, improved some physiological traits such as stomatal conductance, relative water content, chlorophyll index, sub-stomatal CO2 concentration, and photosynthesis rate, cell membrane stability, proline content and secondary metabolites like anthocyanins and flavonoids which can improve the cowpea ability to increase drought stress tolerance.
کلیدواژهها English
