Abstract: Three japonica rice varieties with different eating and cooking quality were investigated under high temperature conditions in greenhouse and natural conditions to reveal the effects of temperature during the grain filling on the activities of the key enzymes for starch synthesis and quality of eating and cooking of rice. Under the conditions of higher temperatures(mean temperature 24.5℃) during grain filling, protein content in rice grain increased and amylose content and taste meter value decreased. Inferior quality varieties were higher in degree of increasing protein or decreasing amylose than supperior quality ones. Reaction in RVA properties to temperature during grain filling varied with rice varieties and RVA indexes. Activities of ADPG pyrophosphorylase, soluble starch synthase and starch branching enzymes increased first and then fell down. Different varieties had different enzyme activities at the same filling stage and differed in the time when enzyme activity reached a peak value. Activities of ADPG pyrophosphorylase and soluble starch synthase responsed dully to the temperature but starch branching enzyme was more sensitive to the temperature and its activity declined when temperature was too high or too low. High temperature is propitious to enhancing the activities of ADPG pyrophosphorylase and soluble starch synthetic enzyme.

Key words: japonica rice, grain filling stage, temperature, key enzyme of starch synthesis

摘要： 选用蒸煮食味品质不同的3个粳稻品种，利用温室高温和自然常温，研究了灌浆成熟期温度对水稻籽粒淀粉合成关键酶活性及蒸煮食味品质的影响。结果表明，灌浆成熟期高温条件下，水稻籽粒蛋白质含量提高，直链淀粉含量和味度值降低，劣质品种提高或降低的程度大于优质品种；RVA谱特性对灌浆成熟期温度的反应因品种和特性而异；灌浆过程中，籽粒ADPG焦磷酸化酶、可溶性淀粉合成酶和淀粉分支酶活性随灌浆进程，酶活性逐渐增加，达到峰值以后，酶活性又逐渐下降，呈单峰曲线，但不同品种酶活性达到峰值的时间和同一时期的酶活性大小有差异；ADPG焦磷酸化酶和可溶性淀粉合成酶的活性表现对温度的影响反应较为迟钝，而淀粉分支酶活性表现对温度变化的反应较为敏感，温度过高过低都降低该酶活性。

关键词: 粳稻, 灌浆成熟期, 温度, 淀粉合成关键酶