Effects Of Nitrogen Fertilizer Application On Grain Yield,Quality And Nitrogen Utilization Of Mechanical Pot-seedling Transplanting Rice

In order to explore the nitrogen application mode and simplify fertilization program for mechanical pot-seedling transplanting rice that high yield,quality and nitrogen efficient utilization,we take Yongyou1540?hybrid japonica rice?and Zhendao18?conventional japonica rice?as the object of research and study the effect of nitrogen rates,nitrogen ratio and loss-controlled urea application.The conclusions are following:?1?The production increases at the early stage and then decreases as the increase of nitrogen application rate,but the response of different varieties to nitrogen application was different.For Yongyou1540,the yield level was the highest(10.30-10.55 t hm^-2)under the treatment of N3,which was significantly higher than that of other N treatments;while the yield of Zhendao18 under N1 treatment was significantly higher than that of N0,but it was not significantly different from other treatments.With the increase of nitrogen application rate,the nitrogen fertilizer agronomic efficiency and nitrogen partial productivity of the two varieties showed a decreasing trend,and the contribution rate of nitrogen fertilizer and the physiological use efficiency of nitrogen fertilizer did not reach a significant level.Nitrogen application significantly increased the chalkiness rate and chalkiness of the grain,and chalkiness rate and chalkiness increased with the increase of nitrogen application rate.The increase of nitrogen fertilizer significantly increased the protein content of rice;the content of amylose increased with the increase of nitrogen application rate,but the change trend of total starch content was different between different treatments,and the sensitivity of starch content of Yongyou1540 to nitrogen application was higher than Zhendao18.?2?When the nitrogen application rate is fixed,rice yield increases first and then decreases with the increase of panicle fertilizer ratio,but the performance of different varieties is different.Yongyou1540 highest yield was obtained(10.65 t hm^-2)under T3treatment?basal fertilizer:tillering fertilizer:panicle fertilizer respectively was 4:2:4?;while the yield of Zhendao18 was the highest(8.43 t hm^-2)under T2 treatment?basal fertilizer:tillering fertilizer:panicle fertilizer respectively was 6:2:2?,but the yield under other treatments was no significant difference.The absorption and utilization rate of nitrogen fertilizer increased with the increase of panicle fertilizer proportion,while the trend of nitrogen partial fertilizer productivity was the same as the yield.With the increase of the panicle fertilizer ratio,the processing quality of Yongyou1540 was improved,but the processing quality of Zhendao18 was not significantly different under the different nitrogen base recovery ratios.The chalkiness rate and chalkiness of Yongyou1540 were the lowest under T3 treatment.The chalkiness rate of Zhendao18 had a tendency to decrease with the increase of panicle fertilizer proportion,but there was no significant change in chalkiness.The proportion of panicle fertilizer was increased and the protein content was increased.However,the excess nitrogen fertilizer shifted backwards,which caused the protein content to decrease.The change trend of starch content was opposite to that of protein content.?3?Compared with the conventional nitrogen application strategy?F1,fertilize four times?,the three fertilization treatments for loss of urea did not significantly increase rice yield and population quality indicators.Even the yield of F4 treatment?basal fertilizer applying 100%N from loss-controlled urea?of Yongyou1540 was significantly lower than that of the control treatment,but overall,the yield of Yongyou1540 under F3 treatment?basal fertilizer applying 70%N from loss-controlled urea+panicle fertilizer 30%N from conventional urea?was 10.72t/hm²,which was higher than other treatments at different levels.The yield of Zhendao18 was the highest under F2 treatment?basal fertilizer applying 80%N from loss-controlled urea+tillering fertilizer 20%N from conventional urea?,but it was not different from other treatments.Under the treatment of F4,N accumulation was more than that of rice,showing a higher nitrogen fertilization physiological utilization rate,but the difference in nitrogen fertilization agronomic efficiency,nitrogen fertilizer absorption and utilization,and nitrogen partial productivity was consistent with the yield trend.