Studies on the dynamic status of nitrogen and carbon, and their efficient utilization in crop production

本研究旨在阐明与植物体内氮代谢密切相关的禾本科作物、豆科作物和蔬菜作物的植物与土壤间氮循环及碳的动态状况。从水稻研究中得到的结果总结如下：水稻氮素循环：不同品种间氮素利用效率的差异。认为应采用高原子率的^<15>N来监测土壤中残余肥料氮。水稻不同生育期氮素的吸收和转运：早期追肥产生较大的顶干重和较小的籽粒产量。氮素利用效率因品种而异，追肥后期效率较高。3 .水稻苗期性状对水稻移栽后即刻氮素循环的影响：苗期性状不同的水稻植株在移栽后氮素吸收和叶片、茎向根系的再转运方面存在差异。4 .水稻幼苗生根期氮碳循环：定植后，氮碳由下部叶片和叶鞘向上部叶片和叶鞘转移。不同生根区水稻植株氮素利用效率：生根区越大，水稻植株氮素利用效率越高。抽穗期和成熟期氮素利用效率均以基肥高于追肥。不同水稻品种对^<15>氮素分配的山内互作：不同植株类型的2个品种伴栽时，根区大小对氮素的吸收率不同。在4年的时间里，对禾本科和豆科作物以及水稻以外的蔬菜作物进行了10项研究。

This study is an attempt to elucidate the dynamic status of mitrogen circulating between plants and soil and carbon closely related with mitrogen metabolism in the plants for gramineous crops, leguminous crops and vegetable crops. The results obtained from rice study were summarized as follows:1. Nirogen circulation in rice plants grown in paddy fields: Nitrogen-use efficiency varied among varieties. It was recognized that ^<15>N with high atom% should be used for monitoring residual fertilizer N in soil.2. Up-take and translocation of nitrogen applied at different growth stages in rice plants: Earlier topdressing produced greater top dry weights and smaller grain yields. Nitrogen-use efficiency varied among varieties, with higher efficiencies in later topdressing.3. Effects of character of rice seedlings on nitrogen circulation in rice plants immediately after transplanting: Rice plants with different characters during the nursery period varied in nitrogen up-take and the re-translocation of nitrogen from leaf and stem to root after transplanting.4. Circulation of nitrogen and carbon in rice seedlings at rooting stage: After transplanting, nitrogen and carbon are translocated from the lower leaf blades and leaf sheath to the upper ones.5. Nitrogen-use efficiency of rice plants in different rooting zones: Nitrogen-use efficiency of rice plants was higher in the larger rooting zones. The nitrogen-use efficiency at the times of heading and maturity was higher in base dressing than in topdressing.6. Intra-hill interaction of different rice cultivars on ^<15>N allocation: In the companion planting of two cultivars differing in plant type, nitrogen absorption rate varied among rooting-zone sizes. Ten studies on gramineous and leguminous crops and vegetable crops other than rice plants were conducted during four years.