evaluation of water and radiation use efficiencies of bread wheat (triticum aestivum l.) genotypes under different moisture and photosynthetic conditions

in order to evaluate of yield, water and radiation use efficiencies in wheat genotypes, a field experiment was conducted using a split split plot design based on a randomized complete block design with three replications at khorasan razavi agricultural and natural resources research centre (mashhad, iran) in 2006-2008. main plots were assigned to two levels of water stress treatments; d1: optimum irrigation, and d2: cessation of watering from anthesis to maturity stages. sub plots were assigned to eight bread wheat genotypes: 9103, 9116, 9203, 9205, 9207, 9212, c-81-10 and cross shahi (control); and photosynthetic conditions with two levels: p1: using of current photosynthesis and p2: inhibition of current photosynthesis were in sub-sub plots. grain yield were significantly influenced by irrigation treatments and source limitation. grain yield significantly decreased by 35% and 68% under d2 (2976 kg ha-1) and p2 (1830 kg ha-1) treatments, respectively compared with d1 (4577 kg ha-1) and p1 (5722 kg ha-1) treatments. moisture stress decreased wueg and rue. wueg significantly decreased by 18.31% and 64.42% under d2 (0.687 kg m-3) and p2 (0.401 kg m-3) treatments, respectively compared with d1 (0.841 kg m-3) and p1 (1.127 kg m-3) treatments. wueg decrease due to water deficit was attributed to grain yield reduction. genotypic differences exist in related to mentioned traits, as at optimum irrigation and cessation of watering conditions, the highest wueg achieved from 9103 and c-81-10 genotypes, respectively; and the less wueg at d1 and d2 conditions was obtained from cross shahi variety. according to results of this experiment, c-81-10, 9103 and 9116 genotypes could be introduced as promising genotypes and desirable for cessation of watering condition, and used them in breeding programs.