Effect Of Sucrose Metabolism And Starch Accumulation On Different Wheat Under Drought Or Re-Water During Filing Stage

Drought is one of the major constrains in wheat production in the north. In practice, the drop of yield is to remit by mean of Supplemental irrigation. With the crisis of water resource shortage, it is of signality to explore water requirement of wheat for realizing high yield and high efficiency crop production. Crop yield is not only depending on produce of photosynthate, but also including reasonable assimilating translocation and distribution. Therefore, the study of drought and re-watering to regulate produce and transport of assimilate will provide theoretical basis for high crop yield and high water using efficiency.A pot cultivation experiment was carried out on October 26, 2009 to June 5, 2010. Drought-resistant varieties Changhan 58, Changwu 134 and water-sensitive wheat Xinong 9871 ware selected as experimental material. Form jointing stage regulation of water, wheat were given low water stress (60%~65% of field capacity) and mid water stress (50%~55% of field capacity) before flowering period or after, respectively. Before jointing stage all treatments were well-watered. In that condition, sucrose metabolism, starch accumulation, yield and WUE were studded. The main results as follow:1. Photosynthesis was controlled by stomata factors during the early or mid filling stage, while the drop of photosynthesis during the late filling stage due to non-stomata factors with degradation of chloroplast. The process of leaf senescence was accelerated under water stress; on the contrary, that was delay under re-water condition.2. Net photosynthesis rate of dry land wheat variety made Compensatory effects under re-watering during grain filing stage as well as SPS activity, sucrose content. Besides, compensation effect was more obvious, with the water stress more aggravate, which was better than water-sensitive cultivar Xinong 9871.3. Drought had little effect on leaf net photosynthetic rate of dryland wheat flag during grain filling stage, which enhanced SPS activity of leaf and sucrose content was increased during the early filling stage; The drought during the late filling stage accelerated senescence of the flag leaf, meanwhile SPS activity and synthesis of sucrose content were reduced largely with the severity of stress after flowering, and that of water-sensitive wheat dropped more largely.4. transport of photosynthetic products were increased when they were re-watered after flowering, so that seed sucrose content were increased as well as SS activity in grain, which promoted jointly the synthesis of starch, and starch accumulation rates maintained high level in the late filling.5. starch accumulation rate was accelerated by drought occurring in early grain filling stage, and to achieve maximum speed in advance, and drought during the late filling stage benefited assimilate transporting to seeds and sucrose content in grain was increased, which made a compensate for reduce of yield of wheat. However, with decreased of SS activity in late stage, starch synthesis in grain was blocked, that cause decline in production.6. Drought before flowering made appreciable impact on spike of wheat, number of spikelets and spike decreased significantly with the severity of water stress; while TKW of wheat was decrease when drought occurring after flowering, of which water-sensitive variety had a maximum decline was 8%.7. Moderate water stress before flowering is conducive to reach rational allocation of assimilates, which reduced the growth of redundancy and increased harvest index. The harvest index of Changhan 58, Changwu 134 and Xinong 9871 exceeds the CK 14.1%, 15.3%, 17.1%.8. Whatever water stress happening in the flowering before or after, which can improve the Yield water use efficiency (YWUE) of dryland varieties with different levels, of which Chang 58 varieties with low water stress after flowering had a larger increase, moderate water stress significantly reduced YWUE of water-sensitive Variety.Therefore, drought-resistant varieties could adapt changing environment of low water and there is little effect on drought-resistant varieties affected by drought than water-sensitive one. Besides, water-sensitive variety had little compensation effect.