两种产量水平下超级杂交稻氮素吸收利用特性OA北大核心CSTPCD

This study aims to investigate the characteristics of nitrogen(N)uptake and utilization in super hybrid rice grown under two yield levels to provide a theoretical and practical basis for super high-yield rice cultivation and super hybrid rice breeding in southwest China.Field and pot experiments were conducted in Deyang City(a high-yielding site,HYS)and Luzhou City(a medium-yielding site,MYS)between 2018 and 2020.Each year,two super-hybrid rice cultivars('Deyou4727'and'Luyou727')and two high-yielding inbred rice cultivars('Jinnongsimiao'and'Huanghuazhan')were planted at each site.Differences in N uptake,translocation,and utilization characteristics between the two yield levels and the four rice cultivars were studied.The results showed marked diffe-rences in grain yield,N uptake,and utilization between the two sites in the field experiment.Super-hybrid rice produced higher grain yield and partial factor productivity of applied N(PFPN)in HYS in comparison to those in MYS by 8.3％-23.2％and 8.3％-23.1％,respectively.Super-hybrid rice exhibited higher N uptake and rate of N uptake from sowing(SO)to panicle initiation(PI)and PI to full heading(HD)in HYS in comparison to MYS(except for the duration from PI to HD in 2018).However,HYS demonstrated high-er N accumulation during the grain-filling period of super-hybrid rice.Consequently,super-hybrid rice demonstrated 15.6％-33.7％higher total N uptake in HYS in comparison to MYS.On average,despite HYS showing a 4.6％higher N harvest index in super-hy-brid rice compared to MYS(except in 2018),a substantial amount of N was still retained in the straw at the maturity stage.Con-sequently,HYS demonstrated 11.3％lower N use efficiency for grains production(NUEGP)than MYS.Analysis of variance re-vealed that the effects of soil,the interactions of year(Y)×soil(S),S×location(L),and S×cultivar(C)were not significant for grain yield,N uptake,or NUEGP of super-hybrid rice grown in the pot experiments.The trends in grain yield,N uptake,and NUEGP of su-per-hybrid rice grown in the pot experiments were similar to those in the field experiments.HYS experienced a higher mean tempera-ture during the SO-PI phase,whereas the mean temperature was lower in HYS compared to MYS.The cumulative solar radiation dur-ing SO-PI,PI-HD,and HD-MA was higher in the HYS than in the MYS(except for PI-HD in 2018).Further analysis indicated that rice grain yield was significantly and positively related to N uptake accumulation during PI-HD,as well as the N harvest index in the HYS.There was a significant negative relationship of NUEGP with N uptake accumulation,and mean temperature during the SO-PI in the HYS.There was a significant positive relationship between rice grain yield and NUEGP and total N uptake in the MYS.Addi-tionally,NUEGP was significantly negatively correlated with mean temperature during the SO-PI and HD-MA in the MYS.Our find-ings indicated that the differences in grain yield,N absorption,and utilization characteristics of super-hybrid rice at different ecologi-cal sites are primarily related to the climatic factors(including mean temperature and solar radiation during the growing season)of the planted site.