Screening Of Feng-Ai-Zhan No.1 Backcrossing Introgression Lines (BILs) For Nitrogen Use-efficiency

Fifty-four different varieties of rice were screened, evaluated and identified by low nitrogen stress treatment at seedling and whole growth duration. Some high nitrogen use-efficiency rice varieties were selected. At the same time,a screening and identifying method was established. Results were as followed:1. A pot experiment was conducted using 54 varieties rice under different N levels at seedling duration. The results show that there existed significant difference among rice varieties under low-N stress. The relative plant height(RPH) ranged from 70.44% to 112.66%,relative tilling number(RTN) was from 33.89% to97.12%,shoot dry weight (RSDW) was from 25.05% to 80.24%.All these three indices might response to the sensitivity of rice to low-N stress.2. The orders of SD and CV were both RSDW>RTN>RPH.3. According to the order of RTN and RSDW,the rice varieties could be classified into two catalogs, high nitrogen use efficiency(NUE),low-N sensitivity(LNS)and midst. Among the 54 varieties, 8 ones showed HNUE and 6 ones possessed LNS. Those 14genotypes were considered as extreme materials. Which should be valuable in high nitrogen use-efficiency breeding.4. The most sensitive duration of rice to low-N stress appeared at 45 days after sowing, which was observed from the study of 40 extreme rice under two N levels, suggesting that the properly time of high nitrogen use-efficiency rice screening was 45-50days after sowing.5. To evaluate the high nitrogen use-efficiency during the whole growth period in fields. The plant height(PH),tilling number per plant(TN), panicle length(PL),spikelet number per panicle(SN), seed setting rate(SS), 1000-grain weight(100G)and grain weight(GW) were conducted under normal and low-N levels at maturity stage during the whole growth period.The CV order of the tolerance index was :Y(22.3%)>TN(21.8%)>FG(20.5%)>SS(20.1 %)>PL(9.5%)>PH(6.4%)>GW(4.3%).ANOVA showed that among the above 7 traits, except the PL was not significant difference between two N applied levels, the other 6 traits were significant(P<0.01).PL and TN were significant between two lines.6. The relative correlation analysis indicated that these 10 traits were significant correlated each other under two N applied levels.These evidences indicated that the plant height and tilling number per plant could be selected as the screening indices to evaluate the rice high Nitrogen use-efficiency. Because of the tilling number is easier to operate,it was choosed as screening index at large-scale and screening of rice high nitrogen use-efficiency at seedling stage.