Effect of zinc foliar application on the quantitative and qualitative yield and seedlings growth characteristics of bread wheat (cv. Kohdasht)

Due to extent of zinc (Zn) deficiency in soils of Iran and its deficiency in human diet, this study investigated the effect of Zn sulfate foliar applications (non-foliar application, 0.5 g/l at stem elongation stage, 0.5 g/l at stem elongation and grain filling stages, 0.5 g/l at stem elongation and 2 g/l at grain filling stages) on yield and its components (farm sector) and influence of grain Zn contents (low (199 ng Zn grain^-1), medium (381 ng Zn grain^-1) and high (595 ng Zn grain^-1)) on germination and seedling growth parameters of bread wheat (cv. Kohdasht) during 2013-2014 in Maragheh University. The field results showed that Zn foliar application at stem elongation and grain filling stages increased the number of grains per spike, number of fertile spikelet per spike and spike weight of the control (no foliar application). Also, Zn sulfate foliar application in all phonological stages increased the biological yield and economic yield in the control treatment (no foliar application). But, Zn application had no significant effect on harvest index in any growth stages. The results showed that medium (381 ng Zn grain^-1) and high (595 ng Zn grain^-1) grain Zn content significantly increased plumule, radicle and seedling fresh matter weight and also plumule, radicle and seedling dry matter of the low (199 ng Zn grain^-1) grain Zn content. But between low, medium and high grain Zn contents, in terms of plumule length and radicle length were no significant differences, whereas the grain Zn content increased seedling length. High grain Zn content caused significant increase in germination rate, emergence time and seedling vigor indices. But grain Zn content had no effect on germination percentage. Results showed that application of the Zn Sulfate increased grain yield and Zn content of the grain. Therefore, it seems that spraying Zn would improve the quantity and quality of the wheat yield in soils with Zn deficiency. Furthermore, agronomic bio­­fortification could be applied as a short time strategy to decrease nutritional problems due to Zn deficiency and also to improve food security indices. Assessment of germination indices also revealed that incensement of Zn concentration in grain would improve germination indices and seedling vigor.