摘要
摘要:探明高温高湿稻区增密减氮对杂交稻产量形成和氮肥利用率的影响, 可为高温高湿稻区氮肥优化管理和合理密植提供依据。本研究以杂交稻‘内6优107’为材料, 于2018—2019年在典型的高温高湿稻区四川省泸州市进行大田试验。试验设6个密度与施氮量组合, 分别为低密高氮(习惯移栽密度16.5 万穴?hm^?2, 施氮量为180 kg?hm^?2, LDN_ck)、低密减氮15% (LDN_?15%)、低密减氮30% (LDN_?30%)、增密减氮15% (增密27%, HDN_?15%)、增密减氮30% (HDN_?30%)和低密不施氮(LDN₀)。结果表明: 不同密肥组合对杂交稻产量影响显著(P<0.01)。与LDN_ck相比, HDN_?15%和HDN_?30%杂交稻产量分别增加4.3%~4.9%和2.3%~3.6%, 其优势主要表现在每穗粒数、结实率、花前干物质转运量、花前干物质转运效率、花前干物质转运对产量的贡献率和收获指数上。LDN_?15%和LDN_?30%杂交稻产量较LDN_ck分别降低2.3%~2.5%和4.8%~5.0%, 较低的有效穗、干物质、花后干物质积累及花后干物质积累对产量的贡献率是其减产的主要原因。HDN_?15%和HDN_?30%杂交稻花后氮素积累量、成熟期氮素吸收量低于LDN_ck处理, 但其花前氮素转运量、花前氮素转运效率、花前氮素转运贡献率、氮素干物质生产效率、氮素籽粒生产效率和氮素收获指数均高于LDN_ck处理, 因而HDN_?15%和HDN_?30%处理每生产100 kg稻谷需氮量分别减少6.8%~8.4%和9.0%~9.9%。与LDN_ck处理相比, HDN_?15%和HDN_?30%杂交稻氮肥农学利用率分别增加36.7%~37.4%和55.5%~60.4%、氮肥偏生产力增加22.8%~23.5%和46.3%~48.2%、氮肥吸收利用率增加5.6%~12.0%和17.0%~20.0%。可见, 在高温高湿稻区杂交稻生产上宜采用栽插密度为21.0万穴?hm^?2和施氮量为126~153 kg?hm^?2的组合。
关键词:杂交稻/
增密减氮/
产量/
氮肥利用率/
高温高湿
Abstract:The effects of increased plant density with reduced nitrogen (N) application rate on yield formation and nitrogen use efficiency (NUE) of hybrid rice were studied to provide a theoretical basis for optimum nitrogen fertilizer management and plant density under high temperature with high humidity conditions. Field experiments were conducted in Luzhou City from 2018 to 2019. The high yield and high quality hybrid rice variety ‘Nei6you107’ was grown under six combinations of plant density and N application rate: 1) locally recommended combination with a plant density of 16.5×10⁴ hills?hm^?2 and a N rate of 180 kg?hm^?2 (LDN_ck); 2) combination of a plant density of 16.5×10⁴ hills?hm^?2 and a reduced N rate by 15% (153 kg?hm^?2, LDN_?15%); 3) combination of a plant density of 16.5×10⁴ hills?hm^?2 and a reduced N rate by 30% (126 kg?hm^?2, LDN_?30%); 4) combination of a increased plant density by about 27% (21.0×10⁴ hills hm^?2) and a reduced N rate by 15% (153 kg?hm^?2, HDN_?15%); 5) combination of a increased plant density by about 27% (21.0×10⁴ hills?hm^?2) and a reduced N rate by 30% (126 kg?hm^?2 HDN_?30%); and 6) combination of a plant density of 16.5×10⁴ hills?hm^?2 and zero N rate (LDN₀). The grain yield, yield components, dry matter, N uptake and NUE were measured. The results showed that the grain yield of hybrid rice was significantly affected by different combinations of plant density and N rate (P<0.01). HDN_?15% and HDN_?30% produced higher grain yields than LDN_ck by 4.3%?4.9% and 2.3%?3.6%, respectively. The higher grain yields under HDN_?15% and HDN_?30% were attributed to improvement in spikelets per panicle, grain filling rate, translocation of dry matter accumulated at heading stage (TDM_HD), translocation percentage of dry matter accumulated at heading stage (TPDM_HD), contribution percentage of pre-anthesis dry matter translocation to grain yield (CPDMTG_HD) and harvest index. The LDN_?15% and LDN_?30% had 2.3%?2.5% and 4.8%?5.0% lower grain yield than LDN_ck, respectively. The yield gap between LDN_?15%, LDN_?30% and LDN_ck was attributed to the difference in effective panicles, total dry matter, dry matter accumulation from heading to maturity, and contribution percentage of dry matter accumulation from heading to maturity stage to grain yield (CPDMG_HD-MA). The HDN_?15% and HDN_?30% had lower nitrogen accumulation from heading to maturity and total N uptake than LDN_ck, whereas the translocation of N accumulated at heading stage (NTGN_HD), translocation percentage of N accumulated at heading stage (TPN_HD), contribution percentage of pre-anthesis N accumulation translocation to grain N accumulation (CPNTGN_HD), N use efficiency for biomass production (NUEBP), N use efficiency for grain production (NUEGP) and N harvest index under HDN_?15% and HDN_?30% were higher than those under LDN_ck. Consequently, HDN_?15% and HDN_?30% had lower N requirements to produce 100 kg of grain (NRPG) than LDN_ck by 6.8%?8.4% and 9.0%?9.9%, respectively. HDN_?15% enhanced the agronomic efficiency of applied N (AE_N) by 36.7%?37.4%, partial factor productivity of applied N (PFP_N) by 22.8%?23.5% and recovery efficiency of applied N (RE_N) by 5.6%?12.0% over LDN_ck. The HDN_?30% produced higher AE_N, PFP_N and RE_N than LDN_ck by 55.5%?60.4%, 46.3%?48.2% and 17.0%?20.0%, respectively. The rational combination of plant density and N rate can improve panicle number per unit area, grain filling, TDM_HD, TPDM_HD, NTGN_HD, TPN_HD and harvest index, which further increasing the grain yield and NUE. The optimum combination is plant density of 21.0×10⁴ hills?hm^?2 plus N rate of 126?153 kg?hm^?2 in high temperature with high humidity condition.
Key words:Hybrid rice/
Increased plant density with reduced nitrogen/
Grain yield/
Nitrogen use efficiency/
High temperature with high humidity



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