The Differance Of Photosynthesis And Sucrose Metabolism In Ear Bracts Of The Dry-land Wheat Cultivars From Different Years

Drought is one of the main abiotic stresses limiting crop growth.With the succession of wheat cultivars,there were some differences in drought resistance among cultivars of different years.Wheat non-leaf organs hold higher stress tolerance.Under drought stress,the ear organs of wheat(Glume,lemma)showed obvious photosynthetic physiological advantages and drought adaptation characteristics.Therefore,the research of water deficit under different in spike photosynthesis characteristics and sucrose synthesis of wheat from different years with theoretical knowledge helps to enrich the winter wheat genetic improvement,has certain theoretical guidance for wheat breeding.This study selected four kinds of different wheat cultivars in dryland under moderate water deficit of flag leaf were determined by photosynthesis,sucrose and key enzymes in sucrose synthesis,starch accumulation characteristics and agronomic traits.The aim was to provide theoretical basis for further revealing the physiological mechanism of drought resistance of wheat ears in different years.The following main experimental results were obtained:1.Flag leaf photosynthesis in 2010 s and 1990 s cultivars were decreased by 15.22% and18.76%,and in 1970 s and 1950 s cultivars were decreased by 8.19% and 10.49% under water deficit.The results showed that water deficit affected the net photosynthetic rate of flag leaf at the whole grain filling stage,and the decline of photosynthetic rate of modern cultivars was significantly higher than that of old cultivars in early grain filling stage.Spike photosynthesis reached the peak at fifth days after anthesis,spike photosynthesis in 2010 s and 1990 s cultivars were decreased by 10.03% and 11.92% and decreased by 20.85% and 53.31% of 1970 s and1950s cultivars under water deficit.Flag leaf and bract chlorophyll content and relative water content in wheat had similar changes under water deficit.The above results show that wheat under water deficit spike relative to the flag leaf that has higher photosynthetic capacity and lasting high water holding capacity and filling stage under water deficit of modern cultivars panicle photosynthesis relative to the old cultivars with better tolerance.2.The trend of the sucrose content in flag leaf was first increased and then decreased during the filling stage,and the sucrose content of spike organ of glume and lemmadecreased rapidly in the early stage of filling,the results showed that the spike organ mainly to grain transport of photosynthetic carbon assimilation in the early stage of grain filling.The changes of SPS and SS enzyme activity and sucrose content is similar to that of ear organs of wheat mainly sucrose to grain transport in the early and middle stage,but SS activity significantly increased at early grain filling stage,and decreased at late grain filling stage under water deficit.Sucrose synthesis of flag leaves and ear organ of wheat play an important role under water deficit,and the SPS and SS activity of glume and lemma modern cultivars changhang 1 and Jinmai 47 were significantly higher than that of old cultivars Shanhe 6 and Bima 1at premetaphase grain filling stage.The results showed that the ability of sucrose synthesis of modern cultivars was higher than that of old cultivars,while those with water deficit had better drought tolerance than those of old cultivars.3.Under water deficit,2010 s Changhang1,1990 s Jinmai 47,1970 s Shaanhe6 and1950 s Bima 1 grain weight decreased by 2.92%,8.06%,10.21% and 12%,grainweight decreased by 4.05%,26.54%,16.05% and 22.61%.From the agronomic traits of dryland wheat in North China can be seen in the evolution of Chinese with drought tolerance were gradually increased.Uunder water deficit,The water use efficiency of grain increased by23.13%(P < 0.05)in 2010 s variety Changhang1,but in 1970 s variety Shaanhe6 and 1950 s variety Bima 1there were no significant changes.With the evolution of time,the water use efficiency was gradually improving of dryland wheat in northern Chinese,while the modern cultivars compared to the old cultivars that the modern cultivars had a strong tolerance to drought.