水保所知识产出(1956---)知识库

Crop tolerance and avoidance are critical adaptation mechanisms to cope with drought stress but they contribute
differently to grain yield formation. Little is known about the different roles of these two mechanisms in long-
term crop breeding. A meta-analysis was conducted to determine the different effects of drought tolerance
and avoidance mechanisms on the drought adaptation of wheat crops. The meta-analysis summarized the results
of 283 published papers in international journals, and illustrated that primitive wheat genotypes, including wild,
cultivated diploids, tetraploids and old hexaploids, preferentially showed a drought avoidance strategy, as evi-
denced by large root biomass, small leaf area, and reduced stomatal conductance under water deficits. Modern
hexaploid genotypes showed stronger drought tolerance advantages, such as high leaf water potential and os-
motic adjustment, with a small root system. The meta-analysis indicated that the breeding process of dryland
wheat has been continuously enhancing drought tolerance while weakening drought avoidance. Under severe
water deficits, old hexaploid wheat genotypes with drought avoidance characteristics showed lower reduction of
aboveground biomass and yield than modern genotypes with stronger drought tolerance features, while under
mild and moderate water deficits genotypes with stronger drought tolerance features had higher yields and
aboveground biomass. The meta-analysis provide information for making decisions on the direction of modern
crop breeding and the implementing of managing practices