Effects Of Different N Application Rate On Early Super Hybrid Rice Yield Formation,Nitrogen Utilization,Quality

In order to identify the Characteristics of nitrogen utilization,yield formation and quality under different N application amounts of different early super hybrid rice,a field experimnets were carried out with4early-season super hybrid in comparison with ordinary hybrid. These varieties have been widely grown by rice farmer in Chian. Under five nitrogen levels(0,135,165,195and225kg/ha) to investigate the early-season super hybrid irce nitrogen absorption, the higest producitvity and its fomation mechanism etc, for the rice high-yield, high-yield, high-quality and high-efficicency production provides theory basis. The main result of study was as following:(1)As for all varieties, the correlation between grain yield and N rate showed a singly peak curve during0-225kg/ha. The varieties studied reached maximum output, the highest nitrogen population productivity, in the nitrogen level of195kg/ha, except that03you66and ordinary early-season hybrid rice were in165kg/ha level. In addition to blank processing, there were significant difference in yield betweent the super hybrid and ordinary hybrid, The yield showed the trend that, super hybrice>ordinary hybrid rice. The yields of all varieties were mainly affected by spikelets per panicle and the number of effective panicles.The higher of total number of spikelets of super hybrid rice. Compared with the ordinary early hybrid rice, the higher of leaf area index, population growth rate and high photo synthetic potential of super hybrid early rice had significantly increasing the population dry matter accumulation.(2) The nitrogen accumulation of early hybrid rice increased with the N-application rate.The nitrogen accumulaiotn of super hybrid rice was higher than ordinary hybrice at all growing stage. The accumulation were49.40,75.25,127.65and157.31kg/ha in Critical leaf-age for productive, jointing, heading and mature stage of super hybrid rice, compared with ordinary hybrid early rice were increased to3.55%,7.22%,10.36%and11.18%, respectively. The nitrogen stage accumulation increased with N-Application rate at first, amounted to highest level at195kg/ha, then decreased dramatically at225kg/ha except of tiller critical age period. The N-requirement per100kg grain increased with the N-application of all varieties. The nitrogen, physiological efficiency and partial factor productivity of applied N decreased with the N-application. Under the condition of this experiment, the highest yield of super hybrid early rice nitrogen accumulation amount, N-requirement per100kg grain, agronomic efficiency, Nitrogen uptake and utilization rates were189.94kg/ha,2.15-2.23kg,15.01(14.86-15.16)kg/kg,41.27(40.43～42.11)%, respectively.(3) The yields of early-season super hybrids are increased by an average of8.42%compared to that of the ordinary hybrid rice, and the number of effective panicles is increased by10.67%and the number of grains per spike is increased by13.96%, which suggests that the higher total spikelet number is the main reason for the increase of productivity of the early-season super hybrids. Under their respective nitrogen levels of the highest population productivity, compared with the early-season ordinary hybrid, the leaf area indexes at growth stages of the early-season super hybrids are significantly improved except for at the stage of critical leaf age for effective tillers, and a slower decreasing process in leaf area index after the heading. The population photosynthetic potential is increased by9.00%, which could increase dry matter accumulation in super hybrid rice, especially after the middle growth stage. Total nitrogen uptakes of super hybrids are from167.53to191.72kg/ha with an average of182.62kg/ha, and increased by20.02%, among which increased by30.09%from jointing to heading, and28.92%from heading to maturity. The agronomic N use efficiency and physiological N use efficiency of the super hybrids are higher than those of the early-season ordinary hybrid, while the situation is quite the reverse for physiological N use efficiency and partial factor productivity of applied N.(4) As the increase of introgen application, the brown rice rate, milled rice rate, head rice rate of all the rice varieties were improved, and the super hybrid rice were higher than ordinary hybrid early rice. Especially the head rice rate was significant difference in head rice between super hybrid rice and ordinary hybrice, whice was average of6.7%. In general, the chalkiness grain rate were increasesd, but the chalkiness degree is increased as the increase of nitrogen application.On average, the chalkiness rice rate,chalkiness of super hybrice were61.51%,8.68%, respectively. The significantly different betweent the super hybrice and ordinary rice. The of all the rice varieties were decreased slightly as the nitrogen leves. The grain length, length width raion of super hybrid rice were6.48mm,3.09, respectively in this paper. The gel consistency, amylose content of all varieties were improved, and the protein content were decresed as the increased of nitogent levels. The Gel consistency content showed the trend that, super hybrice>ordinary hybrid rice, but the amylose content and protein were the opposite.The Peak viscosity, hot viscosity, final viscosity, breakdown value, return value of all the varieties were descread as the increase of nitrogen amount. The setback, starting gelatinization temperature rise time, peak viscosity had no significant difference with the nitrogen levels.The Set back and Pasting tmeperature of super hybrid rice were significantly higher than ordinary hybrid rice, but the Break down were opposite.