نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه زراعت و اصلاح نباتات، دانشکده کشاورزی، دانشگاه یاسوج، یاسوج، ایران
2 گروه زراعت، دانشکده کشاورزی، دانشگاه تربیت مدرس، تهران، ایران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Introduction
Pinto bean (Phaseolus vulgaris L. cv. Pinto) is one of the most important legume crops within the Fabaceae family, cultivated extensively in tropical and subtropical regions. Despite its sensitivity to drought, this species plays a crucial role in food security and sustainable agriculture due to its rich composition of high-quality protein, complex carbohydrates, and essential micronutrients. However, drought stress represents a major abiotic constraint that significantly impairs crop performance by reducing stomatal conductance, decreasing chlorophyll content, disrupting photosynthesis, and limiting root and shoot development. To address this challenge, regulated deficit irrigation has emerged as an efficient strategy for optimizing water use while maintaining acceptable yield levels. Moreover, the application of plant growth regulators such as brassinosteroids, bioactive, eco-friendly, and steroidal compounds, has been recognized as a promising approach to enhancing plant tolerance to abiotic stress. These compounds contribute to stress mitigation by enhancing photosynthetic efficiency, stimulating the biosynthesis of vital metabolites, and activating enzymatic defence systems, thereby supporting plant growth and yield under water-limited conditions. Numerous studies have demonstrated that foliar application of brassinolide, particularly during sensitive developmental stages such as flowering, can substantially alleviate the adverse effects of drought and improve agronomic traits and seed yield. Consequently, the integration of deficit irrigation practices with exogenous brassinosteroid application represents a synergistic and effective approach for improving productivity and sustainability in pinto bean cultivation under arid and semi-arid climatic conditions.
Materials and Methods
To investigate the effects of foliar application of 24-epibrassinolide on morphological and agronomic traits of pinto bean (Phaseolus vulgaris L. cv. Pinto), a split-plot experiment was conducted in a randomized complete block design (RCBD) with three replications in 2022 at the Research Farm of Yasouj University. In this study, the main factor consisted of three irrigation levels based on Class A pan evaporation data: full irrigation (100% of crop water requirement), moderate drought stress (80%), and severe drought stress (60%). The sub-factor included four levels of 24-epibrassinolide foliar application: control (distilled water), 0.05, 0.1, and 0.2 mg.L⁻¹. The foliar treatments were applied to the aerial parts of the plants during both vegetative and reproductive growth stages. The objective of this research was to evaluate the interactive effects of drought stress and 24-epibrassinolide application on growth indices, yield components, and the adaptive responses of pinto bean under limited water availability.
Results and Discussion
The results demonstrated that severe drought stress (60% of crop water requirement) led to a significant reduction in morphological traits, with leaf area index and plant height decreasing by 47.26% and 19.19%, respectively. In contrast, foliar application of 0.2 mg L⁻¹ 24-epibrassinolide significantly improved these traits, resulting in increases of 14.86% and 22.80% compared to the control. Furthermore, yield components including the number of pods per plant, the number of seeds per pod, and hundred-seed weight were markedly reduced under severe drought by 21.42%, 27.56%, and 12.69%, respectively. However, application of the highest 24-epibrassinolide concentration substantially enhanced these parameters, with increases of 105%, 61.56%, and 26.54% relative to the untreated control. The interaction between irrigation and foliar treatment revealed that under severe drought conditions, the application of 0.2 mg L⁻¹ 24-epibrassinolide led to notable improvements in seed yield (44.34%), biological yield (39.78%), and harvest index (7.29%) compared to non-treated plants. Moreover, the highest water use efficiency was recorded under severe drought stress combined with this level of 24-epibrassinolide application, indicating the compound’s significant role in optimizing performance under limited water availability. These findings highlight the protective and stimulatory effects of brassinosteroids in enhancing the growth and productivity of pinto bean under drought stress conditions.
Conclusion
Overall, these findings indicate that foliar application of 0.2 mg L⁻¹ 24-epibrassinolide can serve as an effective strategy to enhance agronomic traits, seed yield, and water use efficiency of pinto bean under both full irrigation and deficit irrigation conditions. This underscores the critical role of this plant growth regulator in improving drought tolerance and sustaining economic yield under water-limited environments.
Acknowledgements
The authors gratefully acknowledge the Research and Technology Deputy of Yasouj University for financial support of this experiment.
کلیدواژه‌ها [English]
Authors retain the copyright.This is an open access article distributed under Creative Commons Attribution 4.0 International License (CC BY 4.0).
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