花后高温对稻米品质及胚乳淀粉粒结构的影响

Effect of High Temperature After Anthesis on Rice Quality and Starch Granule Structure of Endosperm

为阐明花后高温对稻米品质的影响机理,以耐热性不同的2个水稻品系为材料,在人工气候室高温和适温条件下,研究了花后高温胁迫对稻米外观品质、加工品质、蒸煮食味品质及胚乳淀粉粒结构的影响。结果表明,花后高温胁迫条件下,稻米长宽比增大,垩白粒率和垩白度显著增加,精米率和整精米率显著降低,直链淀粉含量和胶稠度降低,蛋白质含量增加;高温下淀粉RVA谱特征值最终黏度、消减值和糊化温度升高,崩解值降低,峰值时间延长,Mg/K比值降低。相同处理条件下,热敏感品系4628稻米品质受高温影响程度大些。花后高温条件下,稻米胚乳淀粉粒排列不紧密,淀粉粒间空隙大,多为单粒淀粉体,导致光线的多角度散射,胚乳透明度降低,垩白形成。花后高温条件下,稻米蛋白质含量的增加、Mg/K降低、稻米RVA谱特征值及胚乳淀粉粒结构的变化可能是导致稻米蒸煮食味品质和外观品质降低的主要原因。

To ascertain the influence mechanism of high temperature after anthesis on rice quality, taking tworice lines including heat- tolerant line 996 and heat- sensitive line 4628 as materials, an experiment wasconducted in growth chambers to investigate the effect of high temperature and optimal temperature afteranthesis on rice appearance quality, milling quality, cooking and eating quality and starch granule structure ofendosperm. The results showed that under high temperature after anthesis, ratio of grain length to width, chalkyrate and chalkiness increased, milled rice rate, head rice rate, amylose content and gel consistency decreased,protein content increased. Under high temperature treatments, gelatinization temperature, final viscosity, setback and peak time increased, breakdown decreased, Mg content and K content increased, Mg/K ratiodecreased. Under the same treatment, rice quality of heat tolerant line 996 was less affected by hightemperature than that of heat sensitive line 4628. Under high temperature stress after anthesis, starch granulehad an incompact arrangement, most of the starch granule existed in the form of a single starch endosperm,refractive index decreased, transparency reduced, and led to the formation of chalk. Under high temperatureafter anthesis, the increase of protein content, the decrease of Mg/K, the change of rice RVA characteristicsand starch granule structure of endosperm could be the main reason of the decrease of rice cooking and eating