Difference Of Compensation And Mechanism Of Different Wheat Variety Under Water Stress And Re-watering

Five wheat cultivars in different drought tolerance were screened to study the effection on yield and water use efficiency (WUE) under water deficit and re-watering during jointing stage. Through analyzing the change of morphological index, canopy temperature and canopy structure of five wheat cultivars under water deficit and re-watering, the rules of drought-tolerance and water-saving cultivars were identified and the reliable morphological index system which fit for identifying water-saving varieties was found.The results showed that:(1)Identified the drought-resistance and water-saving during morphological characters, we could draw two conclusions: First, the drought resistant variety may be based on maintaining adequate water in plant body to adapt to drought deficit, such as Jinmai47, or based on bearing water lost to adapt to drought stress, such as Luohan2. Its morphological and physiological characteristics was affected sharply but could recover well after drought resistance. Second, the basic characteristics of drought tolerance cultivars was with well compensation after re-watering, such as Yumai18; the basic characteristics of water-saving varieties were with morphology to be less affected, but its compensation was weak, such as the Shijiazhuang 8.(2) Using the canopy temperature to identify the drought resistance of winter wheat was basically feasible. Drought resistance varieties maintained a lower canopy temperature under water stress, and no significant different canopy temperature appearedbetween the treatment and CK after re-watering. But canopy temperature was higher than the CK under water stress or after re-watering for drought sensitivity varieties. So canopy temperature can be regarded as identification index for varieties drought tolerance.(3) Wheat canopy structure is an important morphological feature, which mainly effected by genotype, but also the fertilizer, water and environmental. The results showed that transmission coefficient for diffuse (TCDP), radiation penetration (TCRP), mean leaf inclination (MLIA) and extinction coefficient of drought resistance varieties had no obvious change under drought stress and re-watering, but drought sensitivities increased or changed sharply. The drought resistance varieties could maintain stable canopy structure, for example, Jinmai 47. Although Luohan2's canopy structure was affected sharply under the water stress, but could recover quickly after water stress and rebuilt a reasonable canopy structure. However, drought identification could not be simply done according to the changes of canopy structure. The difference of changes of canopy structure under water stress and re-watering need to be further studied.(4) Analyzing the water consumption, yield and water use efficiency of 5 wheat varieties, Jinmai47 and Luohan2 was drought-resistant and water-saving varieties. Because of water use efficiency decreased sharply after water deficit, Shijiazhuang 8 was a water-saving but not a drought-resistant variety. Its drought resistant is weak. Yumai18's drought resistance was third, and water use efficiency was fourth . So Yumai18 had general drought-resistant, but not the water-saving variety. YM 20's drought resistance and water-saving were ranked last so it is neither drought resistant nor water-saving variety.