Can Exogenously Applied N-6-Benzyladenine Increase the Growth, Yield and Nutritional Quality of Common Bean Cultivated in Winter and Summer?

Cytokinins are a class of growth regulators that play an essential role in several plant developmental processes, such as cell differentiation, apical dominance, leaf senescence, nutrient signaling, and chloroplast differentiation. This study aimed to evaluate the effect of application time and dose of N‑6-benzyladenine (BA) on photosynthetic traits, nutrient assimilation, and yield of common bean in the summer and winter seasons. BA was applied at three ontogenic stages (seed, vegetative phenological stage V 3 and reproductive phenological stage R 6 ) and at five doses (0, 3, 6, 9 and 12 g ha −1 ). In summer, BA increased SPAD, relative water content, foliar N and K content and plant height, and reduced electrolyte extravasation. In winter, BA reduced electrolyte extravasation and increased foliar N content, plant height, dry weight, and plant yield. The results of this study indicate a hormetic zone at 3–12 g BA ha −1 and the possibility of toxicity at doses above 12 g BA ha −1 . The effects of BA on plants can be influenced by environmental conditions and ontogenic stage of BA application. The results demonstrate the potential of BA to improve common bean by selecting the optimum application regime that maximizes crop performance. Hence, the application of BA in common bean is promising, mainly because it is a low-cost product that can improve plant physiological, biometric, and productivity traits. Our results contribute to programs directed to increase food production and reduce hunger in a changing world with many environmental challenges and a growing population.