| With the rapid development of social economy and science and technology,people’s living standards are increasing,and the demand for high-quality rice and high-quality rations is becoming stronger.Rice yield and quality are significantly regulated by the source-sink relationship.The improvement of rice quality and the synergistic improvement of rice yield and quality depend on the appropriate source-sink relationship of rice plants.Therefore,in this study,a rice population with different source-sink relationship between different grain-leaf area ratio at grain filling stage was formed by thinning and cutting the leaves at full heading stage.The effects of grain-leaf area ratio on rice yield,rice quality characteristics and their relationship,as well as the relationship between rice starch quality characteristics and rice taste quality,in order to provide data support for enriching high-quality and high-yield rice cultivation techniques.The experiment was carried out in 2021 and 2022 at the off-campus experimental base of Yangzhou University in Sihong County,Suqian City.Two high-quality japonica rice(Yingxiang 1 and Sidao 20)and one high-quality indica rice(Huazheyou 210)were selected as materials,and the rice population with different grain-leaf area ratio(spikelet number/leaf area)was constructed by flower and leaf thinning treatment(leaf cutting 1/3,leaf cutting 1/5,no flower and no leaf cutting,flower thinning 1/4,flower thinning 1/3,flower thinning 1/2).The characteristics and differences of grain filling,rice yield,rice quality and rice starch quality were studied.The relationship between grain filling,rice quality and starch quality under different grain-leaf area ratio was studied.The main results are as follows:With the decrease of grain-leaf area ratio,the seed setting rate and 1000-grain weight of rice increased significantly.Compared with the control,the average seed setting rate decreased by 9.88%～20.98%,and the average 1000-grain weight decreased by 4.70%～7.27%.The average increase of seed setting rate under thinning treatment was 2.60%～6.09%,and the average increase of 1000-grain weight was 3.61%～7.73%.Further analysis of the filling characteristic parameters of superior and inferior grains showed that the decrease of grain-leaf area ratio was beneficial to the increase of final grain weight of each variety,which was mainly manifested in advancing the filling peak of superior and inferior grains and shortening the filling active period of superior and inferior grains.With the decrease of grain-leaf area ratio,the processing quality and appearance quality of rice became better,the protein content increased,the nutritional value increased.As the grain-leaf area ratio decreases,cooking and eating quality decreased.Among them,with the decrease of grain-leaf area ratio,the brown rice rate,milled rice rate and head rice rate of rice showed an increasing trend;the chalky grain rate,chalkiness size and chalkiness degree decreased significantly,the length-width ratio of head milled rice decreased,and the head milled rice showed a rounding trend.Rice protein content and protein component content increased;amylose increased,gel consistency became shorter,taste value decreased.Correlation analysis showed that anylose content and protein content were significantly negatively correlated with taste value under the influence of grain-leaf area ratio,and protein content had a greater effect on taste value.With the decrease of the grain-leaf area-ratio,the small and medium starch granules of rice starch increased,and the starch arranged more closely.The relative crystallinity of rice starch decreased,the order of short-range molecules decreased,the stability of starch double helix structure decreased,and the peak viscosity increased.The peak intensity of rice starch decreased,the lamellar distance increased,the gelatinization temperature decreased,and the retrogradation enthalpy and degree increased.The swelling power and solubility of rice starch decreased significantly.The hardness of rice was negatively correlated with the swelling power,solubility and peak intensity of rice starch,and positively correlated with 1022/995 cm-1.The viscosity,balance and taste value of rice were significantly positively correlated with the swelling power,solubility and peak intensity of rice starch,and significantly negatively correlated with 1022/995 cm-1.It is suggested that increasing the swelling power,solubility and peak intensity of rice starch in the appropriate range and reducing the short-range order of starch may be one of the effective ways to improve the taste value of high-quality rice. |
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