Studies on the characteristics of dry matter production and accumulation of rice varieties with different productivity levels | 不同氮肥群体最高生产力水稻品种的物质生产积累

Chinese. 目的研究不同氮肥群体最高生产力水稻品种间物质生产积累特性之间的差异。方法以长江中下游地区有代表性的50个早熟晚粳品种为供试材料，设置7个氮肥群体（0、150.0、187.5、225.0、262.5、300.0、337.5 kg#8226;hm-2），得出各品种在这7个氮肥群体下出现的最高生产力及其对应施氮水平，将该最高生产力定义为氮肥群体最高生产力。根据各品种的氮肥群体最高生产力将50个供试材料分成4个生产力等级：低层水平（氮肥群体最高生产力≤9.00 t#8226;hm-2）、中层水平（9.00 t#8226;hm-2≤氮肥群体最高生产力≤9.75 t#8226;hm-2）、高层水平（9.75 t#8226;hm-2≤氮肥群体最高生产力≤10.50 t#8226;hm-2）、顶层水平（氮肥群体最高生产力≥10.50 t#8226;hm-2）。在此基础上，对各类型品种间的干物质积累量、叶面积指数、光合势、群体生长率、净同化率等方面进行系统的比较研究。结果（1）在总施氮量0―337.5 kg#8226;hm-2范围内，随着氮肥群体的增加，50个粳稻品种在拔节、抽穗期干物质积累量均显著增加，而成熟期则表现为先增后减的变化趋势。（2）拔节期群体干物质积累量随着生产力等级的增加而减小，抽穗期4个生产力等级间的干物质积累量差异较小，成熟期干物质积累量则随着生产力等级的增加而显著增加。（3）水稻生育前期（播种至拔节阶段）干物质积累量与氮肥群体最高生产力呈显著负相关，表现为随生产力等级增加而减小；而生育中、后期（拔节至抽穗和抽穗至成熟阶段）干物质积累量与氮肥群体最高生产力呈显著正相关，表现为随生产力等级增加而增加。各生育阶段干物质积累量占总干物重的比例变化规律与阶段干物质积累量一致。（4）不同生产力等级水稻品种的经济系数随着生产力等级的增加而显著增加。（5）拔节前4个生产力等级品种间叶面积指数和光合势差异较小，而群体生长率和净同化率则随着生产力等级的递增呈显著递减趋势；拔节至抽穗及抽穗至成熟阶段，叶面积指数、光合势、群体生长率和净同化率均随着生产力等级的递增呈增加趋势。结论氮肥群体最高生产力处于顶层水平品种干物质生产在抽穗至成熟阶段优势明显，具有较高的叶面积指数、光合势、群体生长率和净同化率。

English. Objective The characteristics of dry matter and photosynthetic production of different rice varieties under their best-fit nitrogen levels were studied. Method The field experiment was carried out with 50 early-maturing late Japonica rice varieties, adopted in the region of Yangtze River, under seven nitrogen levels (0, 150.0, 187.5, 225.0, 262.5, 300.0, 337.5 kg#8226;hm-2) to investigate the difference of dry matter accumulation. The highest value of dry matter accumulation under different nitrogen levels was defined as the most productivity of N fertilizer group (MPNG). Then according to MPNG, rice varieties could be classified into four types including low type, middle type, high type and top type. On this basis, the dry matter accumulation, LAI, photosynthetic potential, crop growth rate and net assimilation rate of the four types rice varieties were studied. Result The main results were as follows: In the range of 0-337.5 kg#8226;hm-2 nitrogen application, the dry matter accumulation at jointing and heading of 50 rice varieties were significantly increased, while the dry matter accumulation at maturity increased firstly and reduced afterward with the nitrogen application increasing. Population dry matter accumulation at jointing stage decreased as the productivity level increasing, for the dry matter accumulation of top and high levels were increasing much greater than middle and low levels after jointing, there was a little difference among the 4 productivity levels at heading stage. The dry matter accumulation of top productivity level was significantly higher than the other three productivity level varieties at maturity. There was a significant negative correlation between dry matter accumulation and MPNG at early growth stages, while there was a significant positive correlation between them at the middle and later stages of rice growth. The dry matter accumulation at sowing-jointing stage decreased as the productivity level increasing, while it was increased at jointing-heading and heading-maturity stage. The ratio at each stage changed accordantly with the dry matter accumulation. The economic coefficient of different productivity level varieties significantly increased as the productivity level increasing. Before jointing, the differences of leaf area index and photosynthetic potential of 4 productivity level varieties were tiny, while the population growth rate and the net assimilation rate had a significant degressive tendency; at Jointing-heading and heading-maturity stage, leaf area index, photosynthetic potential, the population growth rate and the net assimilation rate were all increased as productivity level increasing. Conclusion The dry matter production of top level varieties at heading-maturity stage have obvious advantages, they have high leaf area index, photosynthetic potential, population growth rate and net assimilation rate.