Evaluation Of Different Rice Types On Nitrogen Use Efficiency

Rice is one of the most staple food in the world, and makes a tremendous contribution to maintain the world food security. After the first green revolution, semi-dewarf rice cultivars had possessed the prior position in rice grown area, due to it stronger anti-lodging ability. On the opposite of this outstanding achievement, they need a vast amout of nitrogen fertiliser. rice nitrogen use efficiency fall down dramatically, most wasted through surface runoff、soil inflitration, as a consequence cause a very large side-effect on the enviroment, Finally, making an impression pressure to the enviroment. Based on these disadvantage of excessive level of nitrogen input, we must impove the nitrogen use efficiency through selecting and breeding high-efficient rice types, which is the most ideal and promising way to solve this issue. In2012、2013, we conducted this field reseach in Dajin village, Wuxue city, Hubei province, selected8or6rice cultivars based on super hybrid rice、common hybrid rice and ordinary rice, arranged different nitrogen application levels. The aim of the experiment was to estimate the nitrogen uptake and use efficiency between these3rice types; we also analysised the relationship between the nitrogen use efficiency and phsiology parameters; finally to establish the evaluation criterion of rice nitrogen use efficiency. For the tight relationship between nitrogen and rice quality, wo detected the chalk rate and chalkness in different rice types. With following results:1) the result showed that in2012the grain yield difference between these three rice types was small, not reaching the significant level, in2013the yield of super hybrid rice and common hybrid rice was higher than common rice, attributing to the higher spikelets per panical and1000-grain weight of hybrid rice type and higher panicals per suqare meter of common rice type.2) From the aspect of dry weight accumulation and transportation, there was no significant difference in dry weight accumulation, and the same to the Harvest index among rice types under different nitrogen levels at maturity stage. This may be one reason for the small grain yield different among these rice types. Refer to the pre-anthesis dry weight translocation, the vary rang scale among super hybrid、common hybrid and common rice was12.0-64.9%、15.5-55.8%respectively in2012、2013, which indicated the different resoures influx to the rice grain, some primarily came from pro-anthesis dry weight translocation, some came from pre-anthesis dry weight accumulation. Moreover, the result indicated the crop growth rate improve as the nitrogen level increasing, not at significant level, still the CGR from panical initiation to heading stage much higher than from heading to panical muturatiy stage. In2013, the rang of CGR from heading to panical muturatiy stage of commom rice was15.0-18.9g m-2d-1, significantly higher than hybrid rice types, nevertheless due to the shortage lifespan of common rice, they could not produce much more grain yield.3) The results showed that in2012total nitrogen accumulation (TNC)、nitrogen harvest index (NHI)、nitrogen use for grain production effciency (NUEg)、nitrogen use for biomass production efficiency (NUEb) and partial factor productivity (PFPN) in different rice type had no explicit differences, but in2013TNC of general rice and general hybrid rice was higher than super hybrid rice; NHK、UEg、NUEb、PFPN of hybrid rice were significantly higher than general rice; nitrogen agronomy effciency of super hybrid rice and common rice was significantly higher than ordinary hybrid rice; except for YD6, difference of nitrogen recovery effciency was not significant among other cultivars.In our experiment, the sort of different rice cultivars based on different nitrogen use efficiency parameters was not consistent and stability; cause of the influenced by indigeous soil nitrogen supply, agronomy nitrogen use efficiency and nitrogen recovery efficiency of nitrogen were not suitable evaluating indicator here. After correlation and rank correlation analysised among different nitrogen use efficiency estimating parameters, we concluded that nitrogen utilization efficiency for grain production may be a better choice and reliable indicator for breeders.4) Nitrogen treatment had no significant inpact on rice chalky kernel percentage; but chalky kernel percentage and chalkiness had been downregulated by nitrogen level, this indicated higher amount of applied nitrogen fertiliser could improve rice appearance quality. Besides the chalky kernel percentage and chalkiness of HHZ were apparently lower than the other cultivars, proving HHZ’s rice quality was better germplasm resources for breeding high quality rice.