In order to evaluate drought tolerance of wheat genotypes, a field experiment was carried out using a split
split plot design based on a randomized complete block design with three replications in Torogh Agricultural and
Natural Resources Research Station (Mashhad, Iran) in 2006-2007 and 2007-2008. 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; and photosynthetic conditions with two levels: P1: using of current photosynthesis
and P2: inhibition of current photosynthesis were in sub-sub plots. The results showed that effect of water stress
and photosynthetic conditions on grain yield (GY), harvest index (HI), number of kernel per spike (NKS), and
thousand kernel weight (TKW) were significant. There was a significant difference between genotypes for
mentioned traits. The 9103, 9116, and C-81-10 genotypes had the highest grain yield from full irrigation and use
of current photosynthesis. The C-81-10, 9116 and 9207 genotypes had the highest grain yield from full irrigation
and inhibition of current photosynthesis. The best of genotypes for optimum irrigation were C-81-10, 9116, and
9103. The 9103, 9212, and C-81-10 genotypes had the highest grain yield from cessation of watering and use of
current photosynthesis. The 9116, C-81-10 and 9103 genotypes had the highest grain yield from cessation of
watering and inhibition of current photosynthesis. The best of genotypes for cessation of watering were 91030,
9116, and C-81-10. STI indicator had the highest correlation with GY under water stress, and were recognized as
suitable index for recognition drought enduring genotypes. The average of stem reserves utilization among
genotypes was 28.5% and 37.8% under well-watered and post-anthesis drought stress, respectively. Considering
that C-81-10, 9103 and 9116 genotypes showed the highest grain yield, potential for reserves and remobilization
of assimilates under different irrigation conditions; thus, these genotypes could be introduced as promising in
breeding programs for arid and semi-arid regions. |
