Relationship Between Rice Quality And Root Characteristics At Grain Filling Stage Of High-Yield Rice

Rice is one of the main food crops in China.With the improvement of living standards,people have higher and higher requirements for high yield and resource utilization efficiency of rice.Most of the studies on modern general cultivation models focus on yield formation,resource utilization efficiency and grain quality,but few studies have been conducted on rice starch quality and root characteristics of underground parts.In this paper,Yongyou 2640,Wuyunjing 24（2019）and Yangdao 6,Jinxiangyu 1（2020）varieties were used as materials for field experiments.Five cultivation modes were set up,including nitrogen blank area（0 N）,local conventional（control）,increasing density and reducing nitrogen,precise irrigation,and increasing cake fertilizer.The cultivation mode of high yield,high quality and high efficiency of rice was explored,and the relationship between root characteristics and grain quality at filling stage was analyzed.The main results are as follows:1.Rice Yield and Nitrogen Use Efficiency under High YieldCompared with the local conventional treatment（control）,the yield of Yongyou 2640 increased by 6.3%,11.4%and 13.4%under the treatment of increasing density and reducing nitrogen,precise irrigation and increasing cake fertilizer,respectively.The yield of Wuyunjing 24 increased by 2.6%,11.6%and 17.8%,respectively.The yield of Yangdao 6 increased by 10.90%,18.50%and 22.89%,respectively.The yield of Jinxiangyu 1 increased by 6.34%,14.05%and 17.19%,respectively.The increase in yield under the above three cultivation measures was mainly due to the total spikelets,especially the increase in the application of cake fertilizer.It shows that the reasonable optimization of cultivation mode can improve the quality index of rice population,which is beneficial to the yield increase of rice.Compared with the control,the nitrogen use efficiency of Yangdao 6 was increased by 15.69%,24.26%and 26.41%,and the nitrogen agronomic efficiency was increased by 51.74%,77.07%and 94.67%,respectively.The nitrogen use efficiency of Jinxiangyu 1 was increased by 21.17%,27.35%and 35.66%,and the nitrogen agronomic efficiency was increased by 48.90%,83.41%and 92.86%,respectively.These results indicated that the optimization of cultivation mode could increase nitrogen accumulation and translocation in aboveground,and simultaneously improve rice yield and nitrogen use efficiency.2.Grain quality under high yield levelCompared with the control,the rice roughness,milled rice rate,head rice rate,gloss,aroma,taste,taste,appearance,viscosity,balance,taste value,albumin content,gel consistency,breakdown value,starch crystallinity and swelling degree,peak viscosity,hot paste viscosity,breakdown value,final viscosity,short-range disorder structure of starch were significantly improved by increasing density and nitrogen reduction,precise irrigation and cake fertilizer treatment.The number of large starch granules and the surface were smooth and smooth.Significantly reduced the chalky grain rate,chalkiness,globulin,gliadin,glutenin content,setback,peak time,gelatinization temperature,hot paste viscosity,relative crystallinity,shortrange ordered structure of starch,and dents on the surface of starch granules.With the integration and optimization of cultivation modes,the processing varieties,appearance quality,cooking and eating quality,nutritional quality,and physicochemical structure and properties of starch of rice were improved.3.Root morphological and physiological characteristics at high yield levelCompared with the control,the root dry weight,root length,root diameter,root oxidation capacity,cytokinin content in root,root bleeding volume,auxin and cytokinin content in root bleeding sap,and total organic acid content in root exudates of all varieties were significantly increased by the treatments of increasing density and reducing nitrogen,precise irrigation,and increasing cake fertilizer.The above root indexes were gradually improved with the addition of single cultivation techniques.This indicated that the integration and optimization of cultivation techniques could significantly improve the morphological and physiological characteristics of root system in rice.4.Correlation between Rice Quality and Root CharacteristicsCorrelation analysis showed that rice quality was closely related to root characteristics:brown rice rate,milled rice rate,head rice rate,hot paste viscosity,peak viscosity,disintegration value,final viscosity,gel consistency,solubility,expansion degree,relative crystallinity of rice were significantly or extremely significantly positively correlated with root oxidation force,root length,root dry weight,root diameter,root bleeding intensity,Z+ZR content in root,total organic acid content in secretion,and IAA content in bleeding fluid.The 1000-grain weight,seed setting rate,chalkiness rate,chalkiness degree,protein content,amylose content,gelatinization temperature of rice were significantly or extremely significantly negatively correlated with root oxidation,root length,root dry weight,root diameter,root bleeding intensity,Z+ZR content in root,total organic acid content in secretion,and IAA content in bleeding fluid.It indicated that the integration and optimization of cultivation mode could improve the quality of rice and starch,and further regulate the growth of root system in the underground part of rice,so as to achieve the goal of high yield,high quality and high efficiency.