Photosynthetic performance of wheat varieties with different grain-leaf ratios under limited irrigation.

Photosynthetic performance of flag leaf and non-leaf organs,and its correlation to grain-leaf ratio in five different type wheat varieties were studied under one time irrigation at spring.The results showed that higher grain-leaf ratio variety had smaller flag leaf area and erect leaf blade,its leaf area decreased slowly and lasted longer photosynthetic function on grain-filling period,and had dominance in photosynthesis.At the meantime,organs SPAD values of varieties with higher grain-leaf ratio decreased gradually,those non-leaf organs' photosynthetic rate were higher than leaf blade's in the later period of grain-filling.Ear area and non-leaf organs area above flag leaf node was positively and highly correlated with grain weight per ear.Transport percentage of storage carbohydrate in leaf blade,stem,sheath and bracts had positive and high correlation with grain-leaf ratio,the contribution proportion to grain weight of storage carbohydrate in leaf blade,stem,sheath and bracts were 11.17%,23.86%,7.42% and 4.17%,respectively,and the average contribution proportion to grain weight of storage carbohydrate in all non-leaf ratio by breeding or cultivation technology,with strengthening on non-leaf organs photosynthetic functions is very important for obtaining high-yield and super high-yield under water-saving condition.