Genetic variation for the efficiency of nitrogen uptake and use in Bread wheat cultivars of Iran and Azerbaijan

Due to economic and environmental concerns, development of cuttivars that absorb and use nitrogen more efficiently is becoming an important objective of plant breeding programmes. In order to assess the feasibility of breeding such cultivars, genetic variation for nitrogen uptake and use efficiency was studied in 20 bread wheat cultivars of Iran and Azerbaijan, in the centre of origin and diversity. The selected cultivars were evaluated for yield and quality characteristics and nitrogen use indices under 0 and 200 kg ha-1 of nitrogen application at Moghan, North Western Iran, during 2007-2009. High levels of variation were observed among genotypes for recorded traits under both nitrogen application treatments. Genotype×nitrogen interaction effect was significant for all characters, except for nitrogen use efficiency (NUE) of grain dry weight (NUEgdw). Cultivars Girmizigul-1, Azamatli-95, Chamran and Koohdasht produced the hightest grain yield under zero nitrogen application . NUE was determined by the yield and concentration of nitrogen in grain and stable. Under N0kg treatment, the contribution of grain yield (79%) to total nitrogen yield was higher than that of grain nitrogen concentration (21%), while under N200kg treatment the trend was different. The contribution of grain nitrogen concentration (55%) was relatively higher than grain yield (45%). Cultivars Gobustan, Girmizigul-1, Azamatli-95, Chamran and Koohdasht showed the highest NUE. Nitrogen uptake efficiency was a critical factor in both nitrogen application treatments. tIt contributed to 79% and 58% of the variance at N0 and N200kg, respectively. Based on these observations both high grain yield and high N uptake efficiency can be considered as two important criteria for selection of high NUE in in wheat. Cultivars Gobustan, Koohdasht and Chamran showed the highest performance for these characteristics.