| Sorghum is one of the major cereal crops. Sorghum has wide adaptability, with the characteristics of drought and water-logging, saline-alkali and barren resistance, etc. Starch is the major component of sorghum grain. Sorghum grain starch content and the ratio of amylase and amylopectin relate to grain yield and quality and also have great influences on grain milling rate, palatability and brewing efficiency. This study used different sorghum varieties as testing materials to study the difference of starch content, grain starch accumulation regulation and the related synthesis enzyme activities, for confirming sorghum physiological and biochemical characteristics with different grain starch content, and the starch synthesis enzyme mechanism of sorghum with high starch content. The main results were as follows:1. Study results of27hybrids showed, starch yield differs significantly from different sort grain starch content, there was a significant positive correlation between starch yield and biomass, harvest index,1000-seed weight, grain amount, N, K accumulation. And there was significantly negative correlation between total starch content, amylopectin content and grain amount. Thus the higher biomass was to ensure a higher starch production, improvement of harvest index may increase the starch production. There was a higher positive correlation coefficient between grain amount and starch content, grain yield per plant, appropriate improving of grain amount might improved sorghum grain yield and starch production. But grain amount’s increasing will affect the starch content, this could be due to the increasing of grain amount might caused grain weight and grain size’s effect. Therefore, under the premise to ensure a higher starch content, to appropriate increase grain amount can effectively improve the grain yield and starch production.By clustering analysis of starch yield and starch content, to filter out the higher starch yield and starch content variety of Jinza105, Tieza11, Tieza17, and higher starch yield with lower starch content variety of Jinza23, Liaoza11.2. Results showed that sorghum grain starch accumulation appears’S’curve with days amount after flowering from starch accumulation characteristics and related amylase activity discrepancy of sorghum Tieza17which was the higher starch content and sorghum Liaoza11which was lower starch content. Tieza17’s starch accumulation was higher Liaoza11’s. Tieza 17had a relatively longer accumulation timing, the time to reach the maximum accumulation rate is earlier than Liaoza11and accumulation rate was also higher. The SS, SPS, ADPGPase, UDPGPase, GBSS activity in Tieza11grain were higher than Liaoza11, ADPGPase、GBSS activity discrepancy was significant. At earlier stage of starch accumulation, the SSS, SBE activity in Liaoza11grain was higher than Tieza17, but on the contrary at mid-late stage. The DBE activity of Liaoza11was always higher than Tieza17. The relative analysis results showed that the SS, ADPGPase, UDPGPase, GBSS activity will had some impaction to amylose starch accumulation, but the SS, ADPGPase, UDPGPase, SSS, SBE, DBE activity will affect the synthesis of amylopectin.3. Drought stress during flowering stage had some impact to sorghum with different starch content grain starch accumulation, starch yield and yield-related traits. The results showed that both Liaoza11and Tieza17’s grain starch content and its composition had quite difference, the quantity of total starch content was mainly affected by amylopectin content. Drought treatment during flowering decreased the total starch content, amylase content, amylopectin content. Level of drought treatment’s affection during flowering was different from different variety Through comprehensive date, Tieza17’s starch content and the affection of its composition by drought stress during flowering was higher than Liaoza11. The affection of sorghum grain starch yield, production and its related traits by drought stress during flowering was more seriously, and the level of affection differs from different years and varieties.4. Under drought stress during flowering, total starch accumulation, amylase accumulation and amylopectin accumulation appeared trend of decreasing at mid-late starge of grain filling, and the maximum starch accumulation rate and mean accumulation rage were reduced, grain starch accumulation duration was shorten, the time to reach the maximum accumulation rate was earlier. Starch synthesis activity were subject to different degree of impact during grain starch accumulation, the impact of Tieza17’s starch accumulation by drought stress was bigger than Liaoza11. The drought stress during flowering inhibits sorghum starch synthesis activity for different degrees, and cause different degrees of impact on the sorghum grain starch accumulation. The response to drought stress during flowering was also different from different varieties of sorghum and starch composition.5. Drought stress during filling stage declined the sorghum grain starch content, starch yield, yield per plant and1000-seed-weight, made the ear grain number slightly reduce. Starch accumulation quantity and the duration of starch accumulation was reduced, starch maximum accumulation rate was increased by drought stress during filling stage. In terms of amylose, Liaoza11affected was relatively serious, and had less effect on the Tieza17. Amylopectin accumulation was more influenced by drought stress during filling stage. All together, drought stress during filling stage influence on Liaoza11’s starch accumulation was more than Tieza17’s.ADPGPase activity of Liaoza11in the process of starch accumulation, was seriously influenced by filling stage drought, and Tieza17’s affected at the early stage of starch accumulation. Drought stress during filling stage was reduced the activity of SSS and GBSS, but the inhibition of SSS and GBSS activity of Liaoza11is greater than Tieza17. Tieza17’s SBE activity affected by drought stress during filling stage was greater than that of Liaoza11. |
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