Evaluation of Some Physiological Responses Related to Nitrogen and Remobilization of Nitrogen in Wheat Affected by Supplemental Irrigation and Nitrogen Fertilization

Accumulation of nitrogen in vegetative organs and its translocation to grain of wheat are important processes that determine the yield and quality. In order to investigate the effect of supplemental irrigation nitrogen fertilizer on dry matter remobilization, yield and yield components of three wheat cultivars a split-split plot experiment was conducted based on randomized complete block design with 3 replications at Research Field of Kurdistan University, Sanandaj, west of Iran, during 2016-2017. Treatments were two levels of Irrigation (rainfed and irrigation at the booting stage) as main-plots, three rainfed cultivars (Sardari, Azar2, and Rejaw) as subplot and three rates of nitrogen (50 kg/ha N (N1), 100 kg/ha N (N2) and 100 kg/ha N plus 20 kg/ha N (N3) foliar application in Heading stage) as sub-subplot. The results showed that supplementary irrigation increased the concentration of leaf chlorophyll a, chlorophyll b, proline, and glycine betaine and decreased the electrolyte leakage. Supplemental irrigation also increased leaf nitrogen, chaff and total nitrogen content at flowering stage. Rejaw cultivar had the highest leaf nitrogen remobilization efficiency and the lowest total nitrogen remobilization efficiency. N1 fertilizer treatment led to the lowest concentration of leaf chlorophyll a and b, proline, glycine betaine, and nitrogen, and stem, chaff and total nitrogen in both flowering and maturity stages. Nitrogen remobilization was affected by supplementary irrigation and different rates of nitrogen fertilizer. It seems that supplementary irrigation in the booting stage leads to an increase in nitrogen content in the vegetative organs, which is transferred to the grain during the seed filling stage.