Combined Application of Boron and Methyl Jasmonate Through Modulating Tolerance Responses Improves Maize Growth and Yield Traits Under Drought Stress

Abstract

Maize, as one of the most important agricultural crops, is suffering from drought stress due to climate change, leading to a significant reduction in yields and thus food shortages worldwide. Foliar application of micronutrients and phytohormones has been introduced as an effective strategy to combat this condition. Therefore, this field study was conducted to evaluate the potential effect of application of boron (B) (0, 0.5%, 1%), methyl jasmonate (MeJA) (0, 50, 100 μM), and their combinations on maize morphological, physiological, and yield characteristics under irrigation deprivation at eight-leaf and ear emergence stages. Our results showed that water deficit during early and late developmental stages significantly (p<0.05) decreased almost all growth and yield traits compared to well-irrigated plants, while application of different concentrations of B and MeJA, especially B3M2 and B3M3, alleviated the dryness detrimental effects. These observations suggest that combined treatments with B and MeJA can reinforce drought tolerance responses in maize plant. Further, our data revealed that water-stressed plants treatment with a combination of B and MeJA in different ways increased total chlorophyll, chlorophyll a, chlorophyll b, carotenoid, free proline, and malondialdehyde (MDA) contents, quantum yield of photosystem II and activity of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) compared to water-treated plants. It can be concluded that foliar spraying of B and MeJA, especially in a combined manner, can significantly reduce the damage caused by water stress to the quantity and quality of the maize crop by positively regulating and improving the drought tolerance response.