田间穗发芽对四川盆地中籼稻稻米品质的影响

Influence of Preharvest Sprouting on Rice Quality of Medium Indica Rice in Sichuan Basin

【目的】明确田间穗发芽对四川盆地稻米品质的影响,为四川盆地水稻优质生产提供指导。【方法】以桂朝Ⅱ号和西科恢768这2个品种为试验材料,于成熟期收集田间穗发芽和未发芽籽粒,分析穗发芽对稻米加工品质、外观品质、组分及淀粉RVA谱特性的影响。【结果】对于加工外观品质而言,穗发芽导致西科恢768的糙米率、精米率、整精米率分别显著降低4.44%、7.48%、3.83%,桂朝Ⅱ号则分别显著降低13.88%、8.90%、34.94%,穗发芽同时导致西科恢768和桂朝Ⅱ号整精米粒重分别降低10.99%和3.57%。穗发芽导致西科恢768的垩白粒率和垩白度显著增加了23.71%和22.6%,桂朝Ⅱ号则分别显著增加了23.19%和9.98%。较未发芽籽粒(对照),穗发芽导致西科恢768的蛋白质和脂肪含量显著降低0.9%和1.43%;桂朝Ⅱ号则分别显著降低0.35%和0.33%。穗发芽导致西科恢768的淀粉峰值黏度、热浆黏度和冷胶黏度显著降低82.72%、96.68%和95.66%,进而导致消减值和回复值分别显著降低127.71%和95.27%;桂朝Ⅱ号则显著降低56.55%、72.63%和57.66%,其消减值和回复值分别显著降低61.18%和31.83%。相关分析结果表明,淀粉RVA谱特性与加工外观品质和稻米组分密切相关,峰值黏度、热浆黏度和冷胶黏度与糙米率(r=0.752、0.805、0.695)、精米率(r=0.853、0.904、0.801)、整精米率(r=0.651、0.752、0.584)、整精米粒重(r=0.696、0.731、0.709)、蛋白质含量(r=0.708、0.626、0.728)和脂肪含量(r=0.915、0.861、0.946)呈显著或极显著正相关关系,与垩白粒率(r=-0.966、-0.963、-0.945)和垩白度(r=-0.812、-0.834、-0.819)则呈极显著负相关关系。【结论】田间穗发芽严重影响四川盆地中籼稻稻米的加工品质、外观品质与蒸煮食味品质,且不同品种间存在差异。

【Objective】The specific objective of this study was to clarify the effects of preharvest sprout⁃ing on rice grain quality and to provide guidance for the production of high-quality rice in Sichuan Basin.【Method】Using Guichao II and Xikehui 768 as experimental materials,we collected both germinated and ungerminated grains in the field at the maturity stage and analyzed the effects of preharvest sprouting on the milling and appearance qualities,composition,and starch RVA profile of the rice.【Result】In terms of processing appearance quality,preharvest sprouting led to significant reductions of 4.44%,7.48%,and 3.83%,and 13.88%,8.90%,and 34.94%in the brown rice rate,milled rice rate,and head rice rate for Xikehui 768 and GuichaoⅡ,respectively.Preharvest sprouting also led to a reduction in the grain weight of head rice by 10.99%for Xikehui 768 and 3.57%for GuichaoⅡ,respectively.It resulted in a significant increase in the chalky grain rate and chalkiness degree by 23.71%and 22.6%for Xikehui 768,and by 23.19%and 9.98%for GuichaoⅡ,respectively.Compared with ungerminated grains,preharvest sprouting significantly decreased the protein and fat content by 0.9%and 1.43%in Xikehui 768,and by 0.35%and 0.33%in GuichaoⅡ,respectively.Moreover,preharvest sprouting significantly reduced the peak viscosity,hot paste viscosity,and cool paste viscosity of Xikehui 768 and GuichaoⅡby 82.72%,96.68%,and 95.66%,and by 56.55%,72.63%,and 57.66%,respectively.This re⁃sulted in a 127.71%and 95.27%reduction for Xikehui 768 and a 61.18%and 31.83%reduc⁃tion for GuichaoⅡin setback viscosity and consistency viscosity,respectively.The results of the correlation analysis showed that the starch RVA spectral properties were closely related to the processing appearance quality and rice fractions.Peak viscosity,hot paste viscosity,and cool paste viscosity were significantly an positively related to the brown rice rate(r=0.752,0.805,and 0.695),milled rice rate(r=0.853,0.904,and 0.801),head rice rate(r=0.651,0.752,and 0.584),grain weight of head rice(r=0.696,0.731,0.709),protein content(r=0.708,0.626,0.728),and fat content(r=0.915,0.861,0.946),but significantly and negatively associated with chalky grain rate(r=-0.966,-0.963,-0.945)and chalkiness degree(r=-0.812,-0.834,-0.819).【Conclusion】In sum⁃mary,preharvest sprouting seriously decreased the milling,appearance,and cooking and eating quali⁃ties of medium indica rice in the Sichuan Basin,and the influence of preharvest sprouting on rice quality depends on the rice varieties.