Mitigation of drought stress effects on wheat yield via the foliar application of boron, zinc, and manganese nano-chelates and supplementary irrigation

Abstract

The aim of this study was to examine the effect of the foliar application of B, Zn, and Mn nano-chelates in separate and combined forms and determine what level of nano-chelates fertilizer treatment most significantly enhances the grain yield of wheat (Azar-2 cultivar) under rainfed and supplementary irrigation conditions. The experiment was performed as a split-plot experiment with three replications in two crop years (2014–2015). The main plot included two irrigation regimes ((I1) rainfed irrigation and (I2) supplementary irrigation) during two stages of development (spike emergence and grain filling). The sub-plot had eight foliar application levels: B, Zn, Mn, B + Zn, B + Mn, Zn + Mn, B + Zn + Mn, and distilled water (control). The foliar application of B, Zn, and Mn nano-chelates combined with supplementary irrigation or its sole application dramatically increased wheat’s resistance to drought stress. Thousand kernel weight and the number of kernels per spike play a decisive role in grain yield. Therefore, the foliar application of nano-fertilizers can increase grain yield by improving these components. The highest grain yield (2528.33 kg/ha−1) was obtained in the supplementary irrigation condition after the combined foliar application of B + Mn + Zn nano-chelates. This condition led to a 41% increase compared to the highest grain yield obtained under rainfed conditions after the foliar application of Zn nano-chelates (1490 kg/ha−1).