稻米糊化温度特性形成规律研究

A Study on the Formation in the Character of Gelatinization Temperature of Rice Grains

利用差示扫描量热仪(DSC)对花后5d起灌浆期间稻米糊化温度特性进行了研究。结果表明,糊化温度特性是随着谷粒的成熟而逐步形成的,表现出由高到低并逐渐趋于稳定的趋势。低糊化温度水稻品种黄玉B和高糊化温度品种Ⅱ32B的起始糊化温度(To)分别在花后第7天和第9天达到稳定,此后不再显著下降。两个品种花后5d的稻米峰值温度(Tp)和终结温度(Tc)均极显著高于此后的稻米样本;花后7～25d,黄玉B的Tp和Tc都出现了下降-上升-下降-上升的过程,但花后7d和25d的值没有显著差异;Ⅱ32B的Tc的变化与黄玉B相似,但其Tp只出现了一个下降-上升过程,且开花后7d的Tp显著高于开花后25d。这些结果表明,高、低糊化温度品种糊化温度特征的形成可能存在差异,在生产实践中,应该针对不同品种类型加以调控。

The gelatinization temperature （GT） character of rice grains was investigated during grain filling period starting from the 5thday after flowering （DAF） using a differential scanning calorimetry （DSC）. The results indicated that the GT characteristics were gradually formed along with the maturing of rice grains with a trend of changing from high to low then being stabilized before maturing. The onset temperature （To） was almost stabilized on the 7th DAF for the low GT variety Huangyu B＇ and on the 11^th for the high GT variety Ⅱ 32B （no significant decreases were observed later during grain filling）. The peak temperature（Tp） and conclusion temperature （Tc） of 5-DAF rice grains were significantly higher than those of the samples at later stages for both varieties. From the 7^th to 25^th DAF, the To and Tp of Huangyu B presented a ‘decreaseincrease-decrease-increase’ process, but the To and Tp differed insignificantly between 7-DAF and 25-DAF rice grains; the Tc of Ⅱ 32B appeared to be similar to that of Huangyu B, but the Tp of Ⅱ 32B had only a ‘decrease-increase’ process, with a significant higher Tp for 7-DAF rice grains than 25-DAF samples. These results suggest that high and low GT varieties might have a different formation process for the GT characteristic, and hence the GT should be regulated differently in rice production.