Effects Of Different Water Irrigation And Nitrogen Fertilizer Management On Grain Yield And Quality Of High-Quality Double-Cropping Late Indica Rice In South China

With the substantial increase in rice production in my country,the improvement of people’s living standards and the reform of the industrial supply side,research on rice quality is of great significance.Water and fertilizer issues have always been a major difficulty restricting the growth and development of rice and environmental protection.With the promotion of high-quality indica rice in southern China,research on water irrigation methods and nitrogen fertilizer operations is conducive to actual rice production.This experiment uses the southern double-season late indica rice Rongyouhuazhan(ordinary-eating late indica rice),Taiyou 871 and Meixiangzhan(high-eating late indica rice)as research materials,and was carried out in the Jiangxi Agricultural University’s talent cultivation industry-university-research cooperation Shanggao innovation base in 2018 — 2019 and2019—2020,respectively Field experiments on the effects of different water irrigation methods and nitrogen fertilizer management on the yield and yield composition,processing quality,appearance quality,cooking and eating quality,nutritional quality and starch physical and chemical properties of southern double-cropping late indica rice were studied.The main research results are as follows:1.The effect of water irrigation methods on the yield and rice quality of Rongyou Huazhan(normal-tasting late indica rice)and Taiyou 871(high-quality tasting late indica rice): alternate wetting and drying(AWD)can effectively improve the water use efficiency of rice fields,and ensure high-quality eating by increasing the seed setting rate The yield of late indica rice is maintained by stabilizing the number of grains per panicle and the seed setting rate to maintain the yield of ordinary late indica rice.AWD improves rice processing quality overall,but the difference in rice appearance quality between AWD and conventional irrigation(CK)is not significant,while constant flooding irrigation(CFI)significantly reduces the chalkiness rate and chalkiness of rice,which is beneficial to the improvement of appearance quality.Under AWD,the amylose content and gel consistency increase,and the protein content decreases,which is beneficial to improve the palatability of rice cooking.The effect of irrigation methods on the amylose and nutritional quality of high-quality indica rice cultivars is higher than that of ordinary indica rice cultivars.2.High amylose content and low amylose cultivars,both have good thermal stability under AWD.Due to the difference in amylose content,the two cultivars of starch granule size distribution and amylopectin chain length distribution are different.For the high-quality indica rice Taiyou 871,the long chains of medium and small granular starch and amylopectin increased under AWD,which reduced the average chain length and large granules of amylopectin,resulting in an increase in gelatinization temperature;while for ordinary rice Rongyouhuazhan,intermittent irrigation increases the large particles and short and medium chains,which is beneficial to reduce the gelatinization enthalpy.In general,AWD was beneficial to the thermodynamic properties and gelatinization properties of the two varieties of starch,thus improving the processing quality and eating quality of rice.3.Different nitrogen fertilizer management methods,with the nitrogen panicle fertilizer shifts later,the number of effective panicles,the number of grains per panicle,and the seed setting rate show a trend of first increasing and then decreasing.The ratio of base fertilizer,tiller fertilizer and panicle fertilizer is 5:2:3 and 4:2:4,the yield of high-quality late indica rice in southern China was the highest.Nitrogen fertilizer moves later,brown rice rate,polished rice rate and whole rice rate show a trend of first increasing and then decreasing;chalky grain rate and chalkiness show a trend of decreasing first and then increasing;amylose content shows a trend of decreasing first and then increasing;protein was a trend of increasing first and then decreasing.When the ratios of base fertilizer,tiller fertilizer and panicle fertilizer were 5:2:3 and 4:2:4,the yield,processing,appearance,eating and nutrition quality of southern high-quality late indica rice reached the best.4.From the physicochemical properties of rice starch,with the nitrogen panicle fertilizer shifts backward,α-1,4 glycosidic bonds decrease,α-1,6 glycosidic bonds increase,amylose content decreases,amylopectin content increases,starch The increase in relative crystallinity leads to a decrease in the temperature of starch gel,an increase in gelatinization enthalpy,and an increase in starch thermal stability.The nitrogen fertilizer shifts later increases the short chain of amylopectin,increases the small & medium starch granules,increases the peak starch viscosity and disintegration value,reduces the reduction value,and improves the starch taste characteristics.When the ratio of basal fertilizer,tillering fertilizer and panicle fertilizer was 5:2:3,the gelatinization enthalpy,peak viscosity and disintegration values were significantly increased,while the reduction values were significantly decreased.Therefore,the thermodynamic properties and gelatinization properties of starch were the best.Compared with other nitrogen fertilizer management methods,the rice yield and rice quality were the best under 5:2:3 treatment.In conclusion,the ratio of basal fertilizer,tillering fertilizer and panicle fertilizer of 5:2:3 is the best nitrogen application method for yield improvement and quality optimization of high-quality late indica rice in Southern China.