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以不同耐热性品种济麦20和鲁麦21为材料,于花后5~9d进行高温处理,研究了小麦灌浆期高温对籽粒淀粉的积累、粒度分布及合成相关酶活性的影响。结果表明,灌浆期高温显著降低籽粒淀粉积累量,显著降低籽粒淀粉、支链淀粉含量,提高直链淀粉含量和直/支链淀粉比例。高温对济麦20籽粒淀粉积累的影响程度较鲁麦21大。灌浆期高温使小麦籽粒A型淀粉粒的体积、数量和表面积百分比显著增加,B型淀粉粒这3指标则显著降低。高温处理后,济麦20籽粒蔗糖合酶(SS)、ADPG焦磷酸化酶(AGPP)、可溶性淀粉合酶(SSS)、束缚态淀粉合酶(GBSS)活性与对照无显著差异,而鲁麦21上述酶活性则高于对照。济麦20、鲁麦21籽粒上述酶活性分别于花后15d和20d开始低于对照。与其他淀粉合成相关酶相比,高温对籽粒GBSS活性的影响程度较小。两品种处理间籽粒蔗糖含量及SS、AGPP、SSS和GBSS活性的变化趋势,与其籽粒淀粉积累量的变化趋势基本一致。灌浆期高温使籽粒淀粉积累量降低,主要因高温抑制了籽粒灌浆中后期的淀粉合成,这是由籽粒蔗糖供应不足和籽粒淀粉合成相关酶活性下降所造成的。
Different heat-tolerant cultivars, Jimai 20 and Lumai 21, were treated with high temperature for 5 ~ 9 d after flowering to study the effect of high temperature during grain filling on the accumulation of starch, particle size distribution and enzyme activities related to the grain structure. The results showed that high temperature during grain filling stage significantly reduced the starch accumulation in grain, significantly reduced the starch, amylopectin content, increased amylose content and the ratio of straight / amylopectin. The effect of high temperature on the accumulation of starch in Jimai 20 was 21 times larger than that in Lumai. During the grain filling stage, the volume, the amount and the surface area percentage of A-type starch granules in wheat grains increased significantly, while the B-type starch granules markedly decreased. After high temperature treatment, there was no significant difference in activity of SS, ADPP pyrophosphorylase (AGPP), soluble starch synthase (SSS) and bound starch synthase (GBSS) 21 The above enzyme activity is higher than the control. The above enzyme activities of Jimai 20 and Lumai 21 were lower than those of the control at 15d and 20d after flowering respectively. Compared with other enzymes involved in starch synthesis, high temperature had little effect on the GBSS activity. The change trend of sucrose content and SS, AGPP, SSS and GBSS activities between two varieties were basically the same as that of the grain starch accumulation. The high temperature during grain filling stage reduced the accumulation of starch in the grains, mainly due to the inhibition of starch synthesis in the late grain filling stage by high temperature, which was caused by the deficient supply of grain sucrose and the decrease of enzyme activity related with starch synthesis in grains.