Abstract:

【Objective】 The aim of this study is to clarify the relationship of grain protein content with cooking and eating quality in different types of rice varieties and effects of nitrogen fertilizer at late growing stage. 【Method】 Different nitrogen fertilizer levels were applied at heading stage to analyze the relationship between protein and its components contents and cooking and eating quality by using three conventional indica rice varieties and three conventional japonica rice varieties.【Result】 Regardless of indica or japonica, nitrogen fertilizer application at late growth stage significantly increased the protein content of rice, and the response to nitrogen fertilizer significantly varied with varieties, with nitrogen fertilizer exerting much greater effects than varieties. The four components contents all increased significantly with rising nitrogen fertilizer level at late growing stage, and gliadin and glutenin contants showed a greater response to nitrogen fertilizer application. With increasing nitrogen fertilizer level, the amylose content decreased and gel consistency was significantly shorter, the peak viscosity, hot viscosity, breakdown and final viscosity of the starch gelatinization characteristic values followed a downward trend, while the consistence and setback showed a upward trend and the taste value decreased significantly. Correlation analysis showed that the total protein content had an extreme significant negative correlation with gel consistency in indica and japonica rice. The protein content of indica rice also had an extreme significant negative association with the taste value (r=-0.975^**) and peak viscosity, but was negatively associated with the breakdown, and positively or significantly positively interrelated with the consistence and setback. The protein content of japonica rice was negatively correlated with the taste value (r=-0.923^**) and breakdown at extremely significant level, and was significantly negatively correlated with the peak viscosity, and the relationship with the consistence and setback was basically the same as that of indica rice. The taste value of indica rice and japonica rice were all negatively related to globulin, gliadin and glutenin contents at extremely significant level, and albumin accounted for the smallest proportion, which was negatively correlated with the taste value at extremely significant level for indica rice, while had no significant correlation in japonica rice.【Conclusion】 The rising nitrogen fertilizer level at late growing stage significantly increased the protein and its components contents of rice. The increasement of protein content significantly degraded the cooking quality and palatability of rice. At the same time, the augment of four protein components would also deteriorated the taste of rice to varying degrees, especially for globulin and gliadin, the negative effect of glutenin could not be ignored especially in indica varieties.

Key words: rice, subspecies, nitrogen, protein, cooking and eating quality, RVA viscosity

摘要：

目的 为揭示不同类型水稻品种稻米蛋白质含量与其蒸煮食味品质间的关系及其对不同后期施氮水平的响应。方法 以3个常规籼稻品种和3个常规粳稻品种为供试材料,在抽穗期实施不同氮肥水平的处理,分析稻米蛋白质及其组分含量与蒸煮食味品质的关系。结果 不论籼粳亚种,后期氮素肥料均显著增加了稻米蛋白质含量,品种对氮素的反应存在明显不同,但肥料处理效应大于品种间差异。随着后期氮肥水平的提高,稻米中四种蛋白组分含量也显著增加,以醇溶蛋白和谷蛋白对氮肥的施用反应较大;直链淀粉含量有所下降,胶稠度显著变短;淀粉糊化特征值中最高黏度、热浆黏度、崩解值和最终黏度下降,而回复值、消减值呈上升趋势;食味值显著下降。相关分析显示,籼﹑粳稻总蛋白质含量与胶稠度呈极显著负相关;籼稻蛋白质含量与食味值(r=-0.975^**)﹑最高黏度呈极显著负相关,与崩解值呈负相关,与回复值﹑消减值呈正相关或显著正相关;粳稻蛋白质含量与食味值(r=-0.923^**)和崩解值呈极显著负相关,与最高黏度呈显著负相关,与回复值﹑消减值的关系和籼稻基本相同。籼、粳稻食味值均与球蛋白、醇溶蛋白和谷蛋白显著负相关,与清蛋白(即比例最小的组分)的关系,籼稻呈极显著负相关,而粳稻相关性未达显著。结论 后期氮肥水平的增加显著提高稻米蛋白质及其组分含量。稻米蛋白质含量的增加,显著劣化稻米蒸煮品质和适口性。四种蛋白组分的增加均会不同程度地劣化稻米食味,其中,尤以球蛋白和醇溶蛋白的负效应较为显著,谷蛋白对食味的负效应也不可忽视,在籼稻品种中表现更明显。

关键词: 水稻, 籼粳亚种, 氮素, 蛋白质, 蒸煮食味品质, RVA