Differences of nitrogen uptake and utilization of conventional rice varieties with different growth duration | 不同生育期水稻品种氮素吸收利用的差异

Chinese. 目的研究不同生育期类型水稻品种氮素吸收利用的差异，分析提高其氮素吸收利用的途径。方法在群体水培条件下，以88―122个常规籼稻品种（2001―2002）、94个常规粳稻品种（2008―2009）为材料，测定生育期、各器官干物重和氮素含量、产量及其构成因素等，采用组内最小平方和的动态聚类方法将供试品种按播种到抽穗日数（为方便描述本文统称为生育期）从低到高依次分为A、B、C、D、E、F 六类，研究各类品种氮素吸收利用的差异及其原因。结果生育期长的品种抽穗期和成熟期氮素累积量大（籼稻）或较大（粳稻），但结实期吸氮量并无优势；生育期长的品种植株含氮率较低（粳稻）或品种间差异较小（籼稻），单位面积穗数较少（籼稻）或品种间差异较小（粳稻），但其生长日数多、干物质生产量大、单穗吸氮量较大、单穗吸氮强度大（籼稻）或较大（粳稻），干物质生产量、单穗吸氮量、单穗吸氮强度对吸氮量的作用分别大于植株含氮率、单位面积穗数、生长日数对吸氮量的作用；生育期长的品种氮素籽粒生产效率低（籼稻）或中等偏大（粳稻），氮素干物质生产效率较大（粳稻）；生育期长的品种抽穗期、成熟期茎鞘叶中氮素分配比例大，穗中氮素分配比例小或较小（成熟期粳稻）。结论生育期长的品种吸氮能力强（籼稻）或较强（粳稻），氮素籽粒生产效率低（籼稻）或中等偏大（粳稻）。生育期长的品种植株含氮率、穗数或小或无优势，但生长日数、干物质生产量、单穗吸氮量、单穗吸氮强度大。促进干物质生产，提高单穗吸氮强度和单穗吸氮能力有利于提高生育期长的品种氮素吸收量。无论是籼稻品种还是粳稻品种，促进营养器官中氮素向穗部运转，减少茎鞘叶中氮素分配比例，均有利于生育期长的品种氮素利用效率的提高。对粳稻品种而言，成熟期较低的植株含氮率也是生育期长的品种氮素利用效率高的重要因素。

English. Objective The objective of the experiments is to investigate the differences in nitrogen uptake and utilization and analyze the ways to improve nitrogen uptake and utilization of the conventional rice varieties with different growth duration (GD). Method A total of 88 and 122 conventional indica rice varieties were used in 2001 and 2002 and 94 conventional japonica rice varieties were used in 2008 and 2009 in solution culture experiments. The GD, dry matter weight of each plant organ (including root), nitrogen content and grain yield and yield components were measured. Based on GD (from sowing to heading stage) by the MinSSw (dynamic clustering method-minimum sum of squares within groups) method, these rice varieties were clustered into 6 types in the alignment from low to high (A, B, C, D, E and F) for determining the differences in nitrogen uptake and utilization and analyzing their causes. ResultThe rice varieties with longer GD had larger amount of nitrogen absorption (ANU) (indica rice varieties) or comparatively larger ANU (japonica rice varieties) at heading stage and maturing stage, however it is not predominant of ANU at grain filling stage. The rice varieties with longer GD showed a lower nitrogen concentration (NC) (japonica rice varieties) or no difference in the NC among varieties (indica rice varieties), also had less panicle numbers per unit area (indica rice varieties) or less difference in the panicle numbers among varieties (japonica rice varieties). However they had longer growing days, higher dry matter weight, higher ANU per single panicle, stronger nitrogen uptake intensity per single panicle (indica rice varieties) or comparatively higher nitrogen uptake intensity per panicle (japonica rice varieties). The dry matter weight, the ANU per single panicle, nitrogen uptake intensity per single panicle had more impact on the amount of nitrogen uptake than nitrogen concentration, panicle numbers per unit area, growing days in both indica and japonica rice varieties. The rice varieties with longer GD had low nitrogen use efficiency for grain yield (NUEg) (indica rice varieties) or over medium NUEg (japonica rice varieties) and comparatively higher nitrogen use efficiency for dry weight (japonica rice varieties). And the rice varieties with longer GD showed a higher nitrogen distribution percentage in leaf and stem and sheath at heading and maturity stages, and lower or comparatively lower nitrogen ratio in panicle (japonica rice varities at ripening stage). Conclusion The rice varieties with longer GD had stronger nitrogen uptake ability (indica rice varieties) or comparatively stronger nitrogen uptake ability (japonica rice varieties) at heading and maturing stages, and had lower NUEg (indica rice varieties) or over medium NUEg (japonica rice varieties). Although, the rice varieties with longer GD had low nitrogen concentration or panicle number, they had longer growing days, larger dry matter weight, higher and comparatively higher amount of nitrogen uptake per single panicle and nitrogen uptake intensity per single panicle. Improvement of dry matter weight, nitrogen uptake ability per single panicle and nitrogen uptake intensity per single panicle were helpful to improve the amount of nitrogen uptake. The promotion of nitrogen translocation from vegetative organs to panicle, and the decrease of the nitrogen percentage remained in sheath and stem and leaves were both beneficial to improving nitrogen use efficiency in rice varieties (indica rice varieties or japonica rice varieties) with longer GD. For japonica rice varieties, the low nitrogen concentration of rice plant at maturity was also one of the important factors on improving nitrogen use efficiency.