Interactive Effects of Nitrogen and Potassium Fertilizers on Quantitative-Qualitative Traits and Drought Tolerance Indices of Rainfed Wheat Cultivar

Mohammad Hossein Sedri,Ebrahim Roohi,Gniewko Niedbała,Mohsen Niazian

doi:10.3390/agronomy12010030

Abstract

Increasing global food requirements and global warming are two challenges of future food security. Water availability and nutrient management are two important factors that affect high-yield and high-quality wheat production. The main and interactive effects of nitrogen and potassium fertilizers on quantitative-qualitative properties and drought tolerance of an Iranian rainfed cultivar of wheat, Azar-2, were evaluated. Four rates of nitrogen (N0, N30, N60, and N90 kg/ha), along with four concentrations of potassium (K0, K30, K60, and K90 kg/ha), were applied in rainfed (drought stress) and non-stress conditions. The interactive effect of N × K was significant on nitrogen and protein contents of grains at 5% and 1% probability levels, respectively. Different trends of SSI, STI, K1STI, and K2STI indexes were observed with the interactive levels of nitrogen and potassium. The lowest SSI index (0.67) was observed in N30K30, whereas the highest STI (1.07), K1STI (1.46), and K2STI (1.51) indexes were obtained by N90K60 and N90K90. The obtained results could be useful to increase yield and quality of winter rainfed wheat cultivars under drought stress with cool-rainfed areas. N60K30 and N90K60 can be recommended to increase the grain yield and protein content of rainfed wheat under drought stress and non-stress conditions, respectively.

Highlights

Increasing the grain yield and quality of wheat (Triticum aestivum L.), as the most widely distributed cereal crop and major staple food crop in the world, is crucial to meet the growing demands of increasing human population [1,2]
Drought tolerance indices (DTI), such as tolerance (TOL) [11], mean productivity (MP) [11], stress susceptibility index (SSI) [12], geometric mean productivity (GMP) [13], harmonic mean (HARM) [14], relative drought index (RDI) [15], stress tolerance index (STI) [13], yield index (YI) [16], and yield stability index (YSI) [17], which provide a measure of drought based on yield loss under drought condition in comparison to normal condition, are useful tools to assess the tolerance of different genotypes to stressful conditions [18]
Sedri et al [3] assessed the effect of different concentrations of nitrogen fertilizer (0, 30, 60, 90, and 120 kg/ha) on DTI of mean productivity (MP), GMP, TOL, SSI, STI, and modified stress tolerance index (MSTI), in a rainfed wheat cultivar and reported that drought tolerance of nitrogen-treated plants was significantly more than control plants, and STI was the best index for drought tolerance assessment

Summary

Introduction

Increasing the grain yield and quality of wheat (Triticum aestivum L.), as the most widely distributed cereal crop and major staple food crop in the world, is crucial to meet the growing demands of increasing human population [1,2]. Sedri et al [3] assessed the effect of different concentrations of nitrogen fertilizer (0, 30, 60, 90, and 120 kg/ha) on DTI of mean productivity (MP), GMP, TOL, SSI, STI, and modified stress tolerance index (MSTI), in a rainfed wheat cultivar and reported that drought tolerance of nitrogen-treated plants was significantly more than control plants, and STI was the best index for drought tolerance assessment. Potassium is another important nutrient element involved in grain weight, yield, and drought resistance of cereals [31,32]. We hypothesized that yield components, qualitative characteristics, and DTI of Azar-2 would all be affected by the interactions of N and K fertilizers

Experimental Design and Treatments

Statistical Analysis

Results and Discussions