Fundamental Traits Of Indica Rice Varieties (Oryza Sativa L.) With Different Nitrogen Accumulation Capacity And Its Responses To Nitrogen Supplying Levels

Improving nitrogen (N) uptake and use efficiency through genetic improvement of crop varieties and proper cultivation techniques is an effective way to enhance crop yield and planting benefit. N uptake and use efficiency mainly include N uptake efficiency (generally represented by crop N accumulation at different growth stages) and N use efficiency (represented by the amount of dry matter (DM) or grain yield produced per unit absorbed N). Previous studies indicated that there existed huge differences among rice varieties in N accumulation, N use efficiency for biomass (NUEp) and N use efficiency for grain (NUEg), and grain yield of rice varieties increased with increasing N accumulation at maturity, however, there were no consistent results concerning the effects of NUEp and NUEg on grain yield of different varieties. To date, there is no information on the combined effects of N accumulation, NUEp and NUEg at maturity on rice grain yield; fundamental traits of high N accumulation types of indica rice varieties were neglected with respect to yield formation, DM production and distribution, N distribution, source sink relationship and root, and the responses of different N accumulation types of indica rice varieties to different N application concentrations also need further investigation. In order to elucidate these issues, eighty eight and one hundred and twenty two conventional indica rice varieties were solution-cultured under the same N concentration in 2001 and 2002, respectively, and eighteen indica rice varieties with different N accumulation...