Effects of nitrogen fertilization on nitrogen use efficiency and yield of machine-transplanted long–age rice seedings

Nitrogen management was used to remedy the negative impacts of the long age seedlings on growth of rice after being transplanted by machine. The effects of nitrogen management on yield and nitrogen use efficiency(NUE) of machine-transplanted rice were studied with gangyou906 as test material, and with the amount of nitrogen application and the proportion of nitrogen as two factors. The results show that the nitrogen accumulation dynamics of the machine-transplanted rice is in a pattern of the logistic curve, the total N accumulation amount of rice plants is increased with the increase of N application amount, while the nitrogen grain production efficiency(NGPE), N harvest index(NHI), N Agronomic efficiency(NAE) and N physiological use efficiency(NPUE) are decreased, and the N use efficiency (NUE) is increased at first and then decreased. The NTE, NHI, NAE, NPUE and NUE are increased under higher panicle fertilization proportion at the same N application amount, while the NGPE is decreased. The yield of the machine-transplanted rice is increased with the increase of N application amount. The amount of N application has significant influence on the effective panicles and the filled grains of per panicle, and the rate of fertile tillers, seed-setting rate, percentage of filled grain and grain plumpness are increased with the postponing of N application proportion. The optimal N application amount for the machine-transplanted rice with long seedling age is t 225 kg/ha with the base N : tillering N : panicle N at 4:3:3.