Effect Of Nitrogen Application On Ratooning Yield And Rice Quality

Ratooning rice is a special cropping system that it has a twice harvest after the first crop.The reason is that the dormant buds on rice stubble after the first harvest germinate into regenerating panicle. Nitrogen fertilizer management in the ratooning season has important effects on ratooning yield and rice quality.Optimization of nitrogen fertilizer management in ratooning season has promoting impacts on the cultivation management system.The field experiments were conducted in 2014 and 2015 at Jiupu village,Qichun county,Huanggang city,Hubei province.The tested varieties included SLY5814,XLY223,HHZ,YY673(2014),HM122(2015).The treatments were arranged in split-split plot design with four replications.Bud fertilizer treatments were the main plots,tiller fertilizer treatments were the split plots and genotypes were the split-split plots.The objectives were to study the effect of nitrogen application in ratooning season on ratooning yield and ratooning rice quality.The main results were obtained as follows:1. Bud fertilizer treatment significantly increased ratooning yield,the increment in bud fertilizer treatment was higher than that in tiller fertilizer treatment,the rate of increase was in the range of 8.1 to 32.9%,mainly because bud fertilizer significantly increased panicles per unit area.2. The optimum fertilizer in ratooning season should be based on variety properties and bud fertilizer application.In N0 treatment,suitable rate of tiller fertilizer application for HHZ was 28 kg N hm-2;For HM122,optimum tiller fertilizer was28 kg N hm-2;For XLY223,optimum tiller fertilizer rate was 52 kg N hm-2;76 kg N hm-2 of tiller fertilizer was recommended for SLY5814.Considering the yield-increasing effect and nitrogen utilization efficiency,in N1 treatment,suitable rate of tiller fertilizer application for HHZ was 28 kg N hm-2;For HM122,optimum tiller fertilizer was 28 kg N hm-2, For XLY223,optimum tiller fertilizer rate was 52 kg N hm-2;52 kg N hm-2 of tiller fertilizer was recommended for SLY5814.3. Amylose content in T2 treatment with N1 treatment was significantly higher than amylose content in T1 or T3 treatment.That condition was beneficial to improve cooking and taste quality of rice varieties with low amylose content.From the synthetic evaluation of the rice quality metrics,the first and ratooning rice quality of HHZ and HM122 were better than SLY5814 and XLY223.4. The effect of nitrogen application on ratooning ability were different.Bud fertilizer treatment increased ratooning ability.Different tiller fertilizer treatments had different effects on ratooning ability,it should be based on varieties.In addition,bud fertilizer could exuberant growth of ratooning buds in early stage.The number of ratooning buds in N1 treatment were higher than that in N0 treatment. Different tiller fertilizer treatments had different effects on ratooning buds nunber,the effects should be based on varieties.5. Different nitrogen application in ratooning season had different effects on the matter quantity of the stubble transferring to ratooning rice.Bud fertilizer significantly enhanced nitrogen accumulation of stubble,improved nitrogen translocation and transferring rate of the stubble transferring to ratooning rice and nitrogen residue of stubble in different degrees.