Effects of Zn nano-chelate foliar application on some physiological parameters and grain yield of soybean under water deficit stress

In order to the investigation of  Zn nano-chelate foliar application effects on photosynthetic parameters, glutamine synthetase, protein, grain yield and yield components of soybean under water deficit, a split-plot experiment was conducted as a randomized complete block design with three replications at Research Farm, Faculty of Agriculture, University of Lorestan, in 2016. The treatments consisted of irrigation regime (100, 80, 60 and 40% of plant water requirement) in the main plots and zinc nano-chelate foliar application (Control or distilled water and zinc as zinc nano-chelate containing 20% zinc absorbable ion) in the subplots. The results showed that by decreasing of water requirement some traits such as photosynthesis, transpiration, stomatal conductance, glutamine synthetase, the number of pods per plant, the number of grain per pod, 100-grain weight, grain yield, protein percentage of grain and protein yield were reduced. In contrast, internal CO2 concentration (Ci) and SPAD value increased in stress condition. In normal condition, zinc nano-chelate treatment was not any effect on SPAD value, the number of seed per pod, 100-seed weight, seed and protein yield. In water deficit conditions, zinc nano-chelate foliar application increased the mentioned traits by 4.2, 13.8, 17.3, 45.7 and 39.3 percent, respectively. In addition, in water deficient, zinc nano-chelate decreased Ci and stomatal conductance of leaves. In general, zinc nano-chelate application mitigated effects of water deficit and it was positive for improving soybean yield. Therefore, its application may improve tolerance of soybean.