Effect Of Genotype And Nitrogen On Appearance Qualitiy And Milling Quality Of Major Japonica Rice Cultivars In Jiangsu

Genetic and cultivation improvement of rice quality is part of the key areas of scientific research in our country.The appearance quality of rice generally includes Chalkiness and grain shape traits.Milling quality includes Brown Rice rate,milled rice rate,and head rice rate.Jiangsu is the major purchasing areas of rice in southern China.Various improvements of japonica rice in Jiangsu have been made to increase the yield.But the high yield cultivars with high appearance quality is lacking.So breeding new cultivars with high quality and researching the supporting cultivation measures is much important.This article used 18 conventional japonica rice varieties and 2 mutants of Wuyujing3,set three nitrogen treatments:CK,control of fertilizer treatments;N5-5 and N10-0,nitrogen fertilizer 200kg/ha;10:0,100%nitrogen fertilizer applied as basal while 0%as topdressing at panicle initiation stage;5:5,nitrogen fertilizer applied equally between basal and topdressing at panicle initiation stage.(1)The major cultivated cultivars of japonica in Jiangsu showed significant genotypic differences in the ratio of chalkiness rice kernel(CRK).None of 20 cultivars matches the Standard of the first class of National Standard for High Quality on appearance quality.Zhendao10,Zhendao11,Ningjing2,Ningjing3 and mutant D12W025 showed the second class of the National Standard for High Quality on appearance quality.Yanjing10,Yanjing13,Zhendao14,Zhendao18,Wuyunjing29 and Wuyunjing30 showed third class of National Standard for High Quality on appearance quality;other varieties did not match the request of National Standard for High Quality on appearance quality.CRK rate of Huaidao5 and Huaidao10 is greater than other cultivars.Chalkiness is one of the foremost problems to improve qualities of japonica rice in Jiangsu.Improving the perfect rice kernel(PRC)rate through genetic improvement and cultivation regulation is a key to solve the problem.(2)The effect nitrogen fertilization mode on the appearance quality,such as CRK,was not significantly.As the total applied nitrogen amount is the same,chalkiness indexes was not significant different between N5-5 and N10-0.Compared with the control(60.6%),N10-0(58.1%)shows no significant differences;compared to N10-0,the CRK rate of N5-5(51.3%)significantly increases.The possible cause of the increase is nitrogen application promotes the generation of other kinds of misshapen rice kernel,such as green rice kernel(GRK),Opaque rice Kernel(ORK).(3)Different cultivars respond to Nitrogenous fertilizer differently.Yanjing 10 showed no difference between the 3 nitrogen treatments.So does Yanjing13 and Zhendao10.Nitrogen application increases the CRK rates of Zhendao14,Ningjing2 and Huaidao10.Nonetheless,the topdressing treatment has no significant effect on Ningjing2 and Huaidao10's CRK rate.Cultivars were categorized according to their response to N treatments.The classification contains no sensitive type,N promoting type and inhibition type.(4)There is significant difference of brown rice rate and head rice rate between different japonica rice cultivars.Zhendao11 and Zhendao16 showed low brown rice rate but high head rice rate,which indicated that the cultivars perform well during the rice milling process.The range of the brown rice rate of the cultivars is 83%-86%,and the range of the head rice rate is 62%-73%.Ningjing1,Ningjing5 and Yanjing13 showed third class of National Standard for High Quality on milling quality,other cultivars showed first class of National Standard for High Quality on milling quality,which indicated that the japonica rice cultivars in Jiangsu have high milling quality.(5)High level of nitrogen application can significantly improve the milling quality of rice.But results showed no significant difference of the milling rice rate and head rice rate,when fertilization shifting from basal to topdressing exhibiting promoting effect.While the shifting showed significant effect to brown rice rate.The head rice rate of N10-0 treatment(69.9%)is significantly higher than CK(68.0%).N5-5 treatment's(70.9%)head rice rate showed no significant difference from N10-0 treatment.So,for most varieties,nitrogen application and shifting fertilizer from basal to topdressing appropriately may promote both yield and milling quality of rice.In that way,we can achieve the coordination of yield and quality of rice.