| Rice is one of the most important food crop in the world.More than half of the world’s population depends on rice for their livelihood,accounting for about 20%of the total energy intake,and the demand is still growing.Field draining is an important technology in rice cultivation.By draining the field it can reduce number of ineffective tiller,the maximum number of seerdlings and the absorption of ineffective nitrogen in later stages of rice,while increase the rice panicle formation rate,and can effectively control diseases such as basic rot of rice to achieve yield increase.In this study,the high-quality rice NJ9108 in Jiangsu Province was used as the material,when the number of tillers reached 70%,80%,90%and 100%of the expected panicle number,respectively,the treatment began to control water and keep the field dry.The study was carried out with randomized block design,each handling three duplicates.Samples were collected at the elongation,booting,heading,and maturity stages of rice to determine agronomic traits and some physiological characters,and extract the mature grain starch to determine starch-related properties through microscopic observation,near infrared light,XRD and other techniques.Finally,through the study on different field treatments the yield and quality of rice and the relationship between the physicochemical properties of grain starch and quality,the best drainage treatment was detarmined.The results were as follows:1.The peak seedling stage was reached about 32 days after transplanting,and the earlier the drainage treatment was,the lower the number of peak seedlings was and the higher the panicle rate was.Before booting,the dry matter accumulation of rice in 90%drainage treatment was higher,while after heading,it was higher in 80%drainge treatment There was no significant difference in leaf chlorophyll content among different drainage treatments at jointing stage,heading stage and mature stage.In addition,the leaf chlorophyll content was higher in 70%and 80%drainage treatment during the wax ripening stage.The leaf area index(LAI)increased continuously with the growth period of rice.At heading stage,due to the increase of invalid tillers,the LAI in 90%and 100%drainage treatments was significantly higher than that in 70%and 80%treatments,and there was no significant difference in other stages.2.Early drainage(70%,80%drainage treatment)could increase the matter accumulation in the late filling stage of rice.The soluble sugar content of leaves in the 100%drainage treatment group was the highest at the heading stage of rice,and it became the lowest at the mature stage,while it was higher in the 70%and 80%treatment,indicating that 100%drainage treatment accelerated the late senescence of rice leaves.There was no obvious difference in MDA content in different drainage treatments 10-30 days after flowering,but at 40-50 days after flowering,the MDA content in early drainage group was less than that in late drainage group(90%,100%),indicating that early dtainage could reduce the degree of cell membrane lipid peroxidation in rice leaves at late filling stage and delay leaf senescence to a certain extent The changes of the activities of the three antioxidant enzymes in the late growth stage of rice were summarized as the higher activities of SOD and POD in rice leaves in the early drainage group,which played a positive role in scavenging oxygen free radicals and delaying the process of premature senescence,which could provide physiological basis for prolonging the time of matter accumulation in the late stage of rice.3.There were differences in yield and quality among different drainage treatments,and the yield of 80%drainage treatment was the highest In terms of quality,the appearance quality,processing quality and cooking quality of early drainage treatment were better than those of late drainage treatment,and 80%drainage treatment is the best.4.Through the observation and statistics of grain starch 10 days after flowering,it was found that the filling proportion of starch in the near aleurone layer was relatively small in 70%and 80%drainage treatments.Particle size analysis showed that the average starch particle size in the early drainage treatment was smaller than that in the late drainage group.The amylose content and solubility in 80%drainage treatment were lower than those of other drainage treatments,while the swelling potential was higher and the disorder was stronger.The peak viscosity,trough viscosity,reduction value,and gelatinization temperature of starch in 80%drainage treatment group were the highest,indicating that the starch granules had the largest degree of swelling,not easy to break,and had good thermal stability.The hydrolysis characteristics of PPA,AAG and HCl of starch showed that the hydrolysis fast period was different under different hydrolysis methods,but under the same hydrolysis method the hydrolysis rate of early drainage treatment was significantly faster than that of late drainage treatment,and the final hydrolysis degree was the same. |
