Effects of Different Cultivation Modes on Yield and Nitrogen Uptake and Utilization of Double Cropping Rice
To explore the effects of different cultivation modes on nitrogen(N)uptake and utilization in double cropping rice,the differences in the yield and the N uptake and utilization of double cropping rice under different cultivation modes were compared by using wide field trial,setting three cultivation modes of machine transplanting(JC),machine throwing(JP)and hand throwing(RP),with Zhongzao 25 and Taoyouxiangzhan as the materials.Results showed that early season rice by JC had the theoretical yield 51.91% and 32.70% higher than that by JP and RP,respectively,and the actual yield 51.62%and 48.78%higher;late season rice by JP showed the theoretical yield 9.45%and 8.26%higher than that by JC and RP while the actual yield 11.66%and 7.07%higher.During the mature period,the total dry matter accumulation amount of early season rice by JC was 51.60%and 131.69%higher than that by JP and RP,while that of late season rice by RP was 17.18%and 3.73%higher than that by JC and JP,respectively.For early season rice,those by JC showed the highest total N accumulation,which was 45.22%and 33.01%higher than that by JP and RP,respectively;while for late season rice,those by JP exhibited the highest value,which was 25.09%and 5.77%higher than that by JC and RP,respectively.Therefore,in northern Hunan,machine transplanting(JC)for early season rice and machine throwing(JP)for late season rice are conducive to the improvement of N utilization rate and rice yield.