[Genetic characteristics of wheat functional leaves at filling stage under different water regimes]

Taking one hundred and fifty doubled haploid (DH) lines of winter wheat cultivars Hanxuan 10 x Lumai 14 as well as their parents as test materials, the genetic bases of top three leaves length, breadth, and angle at mid-filling stage, and their correlations with yield traits were studied under two water regimes rainfed (drought stress, DS) and well-irrigation (WI) in 2005-2007. Under DS, the leaf length and width of DH lines and their parents were significantly lower than those under WI, whereas the leaf angle had a miscellaneous variation. Under the two water regimes, all the test traits of DH lines had a transgressive segregation, with the variation coefficients ranged from 5.1% to 45.9%. The heritability and gene numbers for the given traits showed great differences. Under WI and DS, the heritability of flag leaf angle (FLA) was the highest (91% and 97%, respectively), and that of the third leaf angle (TLA) was the lowest (23% and 31%, respectively). However, the gene number for FLA (4 and 2 under WI and DS, respectively) was the least, and that of TLA (21 and 25, respectively) in 2007 was the most. Interactive effects were observed among the genes controlling FLA, second leaf angle (SLA), and TLA under WI and DS, and controlling third leaf length (TLL) under WI. The grain number per spike and the grain weight per spike were positively correlated with the length and width of top three leaves, and the thousand-grain weight and the yield per plant were significantly correlated with TLL, FLA, and SLA, but all correlation coefficients were smaller ( < 0.481). It was suggested that the selection of top three leaves length and width should be carried out in the early generations of breeding procedure, while that of leaf angles should be carried out in advanced generations. An appropriate soil moisture regime retained in the critical growth period of the leaves would promote their growth and contribute to the grain yield.