Study On The Effect Of Temperature-light Factors On The Formation Of Quality And Yield Of Japonica Rice Along The Yangtze River

Region along the Yangtze River is a main rice-growing area in Jiangsu Province.In order to realize the rational utilization of temperature-light resources and fully excavate the high yield and quality of rice varieties in this region,it is very important to carry out the research on the effect of temperature-light resources on new soft rice varieties in this region.We want to illuminate the temperature-light characteristics for high yield and good quality of different type varieties and the effect that temperature-light factors on cooking and eating quality,then carried out comprehensive comparative evaluation on optimum temperature-light conditions for the coordination of high yield and good quality of different types of varieties along the Yangtze River It is of great significance to ensure the high quality and high yield of rice in this region Therefore,we chose the representative mid-maturity medium-japonica varieties(Nangeng2728,Nangeng505)and late-maturity mediumjaponica varieties(Nangeng9108,Fugeng1606,Fenggeng3227,Wuyungeng80)in the Yangtze River region,set different seeding time treatment experiments(5/10,5/17,5/24,5/31,6/7,6/14,6/21),and systematically compared and analyzed the differences in growth period,yield,quality and starch physical and chemical properties of rice varieties under different temperature-light conditions.Ultimately,we aim to illuminate the influencing mechanism of different temperature-light resources on yield and quality of different types and genotypes at different grain-filling or ripening stage.Then the optimum temperature-light ecology required by the synergy of high yield and good quality of different type varieties along the Yangtze River were compared and evaluated comprehensively.So that we can provide some scientific basis for reasonable sowing time of varieties in this area.The main results are as follows:(1)With the postponing of sowing date,heading and maturity stages of medium-maturity japonica and late-maturity medium japonica are both delayed to varying degrees.Seeding-heading stage is greatly shortened and the whole growth period is shortened.The annual variation trend of temperature factors(average temperature,maximum temperature,minimum temperature,daytime temperature,night temperature,effective accumulative temperature,active accumulated temperature)and radiation factors(daily solar radiation,cumulative solar radiation)in rice growing season was consistent.Rainfall and humidity indicators varied annually.With the delay of cultivation period,the average daily temperature from sowing to heading stage of the three cultivars showed an upward trend,while the average daily temperature from heading to maturity and the whole growth period showed a downward trend.From sowing to heading stage,the effective accumulated temperature increased first and then decreased,while in heading to maturity and the whole growth period,the effective accumulated temperature decreased.The average daily radiation of the three types of cultivars had no obvious rule from sowing to heading with the delay of cultivation period,but showed a decreasing trend from heading to maturity and the whole growth period.The cumulative radiation from sowing to heading,heading to maturity and the whole growth period showed a decreasing trend with the delay of cultivation period.(2)The decreased of EAT and AT of whole growth duration reduces the yield of medium-maturity japonica soft rice,late-maturity medium japonica soft rice and late-maturity medium japonica conventional rice by 0.96%-26.80%、1.89%-29.90%、0.93%-28.89%,respectively.Among the yield components,temperature of seeding-heading stage increased,panicle number and number of grains per panicle decreased.The seed setting rate and the 1000-grain weight decreased significantly when AT of heading-maturity decreased.The correlation analysis of temperature-light factors with yield and its composition showed that temperature indexes such as effective accumulated temperature and average temperature at different growth stages were the main factors affecting yield,followed by cumulative radiation.The temperature characteristics of relative high yield(≥average yield of all treatment)of different types of cultivars were as follows:The EAT of medium-maturing medium japonica cultivars from sowing to heading stage is 1546.4-1601.1℃,and the AT is 27.3-28.1℃.EAT and AT of heading and maturation stage are 687.2-830.0℃ and 22.8-25.1℃ respectively,and that of the whole growth period is 2240.8-2412.5℃ and 26.0-26.5℃.As for late-maturing medium japonica rice,The EAT from sowing to heading stage is 1637.1-1688.6℃,and the AT is 27.4-28.1℃.EAT and AT of heading and maturation stage are 636.5-785.8℃ and 21.6-24.0℃respectively,and that of the whole growth period is 2259.9-2476.6℃ and 25.6-26.2℃.(3)Correlation analysis showed that temperature significantly affected rice processing and appearance quality.When the temperature decreases from heading to maturity decreases,BMRR of medium-maturity japonica soft rice,late-maturity medium japonica soft rice and late-maturity medium japonica conventional rice under S2-S7 treatment are increased by 0.70%-4.55%,0.29%-6.78%and 0.31%-10.54%,respectively,compared with S1 treatment.CD decreased by 2.42-63.18%,7.65%-54.06%,5.20%-55.80%,respectively.The results indicated that the decrease of temperature from heading to maturity was beneficial to rice processing and improvement of appearance quality.Processing quality of three types can reach Grade 2 standard of medium-japonica rice,the EAT of medium-maturity japonica soft rice varieties at the heading-maturity stage is 555.4-830.0℃,the AT is 19.9-25.1℃,the EAT of late-maturity japonica soft rice varieties is 510.9-785.8℃,the AT is 19.1-24.0℃.and as for late-maturity japonica conventional rice varieties,the EAT is 504.1-641.7℃,the AT is 19.2-21.5℃.When appearance quality is above grade 3,the EAT of medium-maturity japonica soft rice varieties at the heading-maturity stage is 555.4-629.6℃,the AT is 19.9-21.6℃,the EAT of late-maturity japonica soft rice varieties is 510.9-584.8℃,the AT is 19.1-20.5℃,and as for late-maturity japonica conventional rice varieties,the EAT and AT is the same as that of late-maturity japonica soft rice varieties.(4)Correlation analysis showed that temperature significantly affected rice cooking and eating quality.When the temperature decreases from heading to maturity decreases,the rice hardness of medium-maturity japonica soft rice,late-maturity medium japonica soft rice and late-maturity medium japonica conventional rice under S2-S7 treatment are increased by 1.59%-29.51%、1.64%-21.82%、2.99%-23.44%,respectively,compared with S1 treatment,viscosity decreased by 1.54%-34.18%、1.23%-28.40%、1.64%-40.98%,respectively,the taste value decreased by 1.32%-19.72%、1.33%-17.72%、2.82%-27.54%.The temperature characteristics of different type cultivars with relatively high taste value(≥the mean value of 7 treatments)were as follow:the EAT of medium-maturity japonica soft rice varieties at the heading-maturity stage is 686.9-830.0℃,the AT is 22.8-25.1℃,the EAT of late-maturity japonica soft rice varieties is 638.6-785.8℃,the AT is 21.6-24.0℃,and as for late-maturity japonica conventional rice varieties,the EAT and AT characteristics are consistent with that of late-maturity japonica soft rice varieties.(5)The lower temperature in the grain filling stage could decrease the content of amylopectin and total starch in the grain at the mature stage,but was favorable to the accumulation of amylopectin in the grain.The early temperature-light treatment is beneficial to the accumulation of total starch and amylopectin,and inhibits the synthesis of amylose.When the temperature decreased during heading and maturation,the food quality of both stem and tiller panicles showed a downward trend.Therefore,the appropriate early sowing temperature in the grain-filling stage in the Yangtze River area can promote the "healthy" early occurrence of tillers,greatly improve the food quality of tiller panicles,and thus improve the food and taste characteristics of rice population.To sum up,temperature factor is the most relevant factor to yield and quality under different temperature-light conditions formed,by the different sowing periods.The temperature indexes of relatively high yield and relatively high palatability of late-maturity japonica soft rice varieties and late-maturity japonica conventional varieties are consistent.The temperature indexes of medium-and late-maturity medium japonica varieties with high yield and high food quality in the low region along the Yangtze River are as follow:The preference AT of medium-maturing medium japonica cultivars from heading to maturation stage is 22.5-25.6℃,and the optimum AT is 24.6-25.6℃;The preference AT for heading is 26.2-31.4℃,the optimum AT is 27.5-31.4℃.As for late-maturing medium japonica rice,the preference AT is 21.4-24.4℃,and the optimum AT is 23.6-24.4℃;The preference AT for heading is 26.2-30.8℃,the optimum AT is 26.3-29.8℃.Light index(total radiation amount)is the secondary index that affects the yield and quality of rice.The higher total radiation in the whole growth period and each growth stage of rice in the area along the Yangtze River is conducive to the formation of high yield and good quality.According to the temperature-light conditions over the years in the area along the Yangtze River,under the two-cropping system of rice and wheat,it is concluded that suitable cultivation period for the coordination of high yield,excellent food and taste was as follow:For the medium-maturity medium japonica varieties,the theoretical suitable sowing date,heading date and maturity date are 5/10-5/24、8/10-8/20、10/5-10/14,respectively;For late-maturity medium japonica varieties,the theoretical suitable sowing date,heading date and maturity date are 5/10-5/20、8/15-8/23、10/9-10/19,respectively.Under the above conditions,earlier cultivation can bring the higher yield and the better quality,but later cultivation can avoid the risk of high temperature damage at heading stage.The yield and quality potential of late-ripening medium japonica varieties are better in this region,and late-ripening medium japonica varieties are more suitable for planting in this region.