Source and Sink Relationship of Five Barley Genotypes Under Different Nitrogen Fertilizer Affected by Water Deficit

In order to investigate the effects of water stress and nitrogen fertilizer application on remobilization and grain yield of barley genotypes, two separate experiments were conducted at the Agricultural and Natural Resources Research Station of Miandoab during the years of 2014–2016 as a split plot based on randomized complete block design with three replications. The treatments included 5 genotypes and four nitrogen fertilizer levels (control or without fertilizer, 50, 100 and 150 kg ha−1 nitrogen (N) fertilizer). Under normal conditions, the maximum remobilization was obtained at 0 and 50 kg N application levels. N application increased non-significantly the remobilization under water deficit stress. The highest (1.22 g.m−2) and lowest (0.91 g.m−2) remobilization were recorded in 100 kg ha−1 N application and control. Bahman genotype, and Karoon and NK1272 genotypes had the highest remobilization under well irrigation and under water deficit, respectively. The highest remobilization to grain yield was related to 100 and 150 kg ha−1 N application. The comparison of N application levels showed that the highest current photosynthesis contribution from seed yield belongs to N application of 150 kg ha−1. Under water deficit, it was allocated to 50 kg ha−1. In conclusion, the greater grain yield in tolerant genotypes under water deficit was due to remobilization of unstructured carbohydrates from shoot to grain. Thus, it seems that selection of genotypes with higher translocated dry matter and contribution of assimilate in grain filling under water deficit, the suitable way for achieving cultivars with high grain yield under water deficit condition.