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).

Keywords:

• Boron
• drought stress
• nano- chelates
• proline
• relative water content
• wheat