QTL analysis of the traits related to sink capacity in rice and their interaction with environmental conditions.

穗部性状是决定水稻产量的重要库容量因子。所得结果如下。（1）以秋光BC_1F_1和IRAT109为材料，对产量构成因素和穗部性状进行了QTL分析。将这些品系在稻田、充分灌溉的高地和少灌溉的旱地上连续两年进行栽培试验。水稻产量的QTL在不同年份或不同栽培条件下发生迁移，在充分灌溉的水、高地中普遍存在。水稻产量的QTL常与每穗颖花数分布在同一区域，说明每穗颖花数对水稻产量的重要性。每穗颖花数主要受抽穗前分化颖花数和败育颖花数的影响。（2）不同施氮量下对同一株系的QTL分析表明，影响水稻产量的QTL随施氮量的增加而移动，但与穗部性状无关，而与收获指数（HI）密切相关。抽穗期植株干重、抽穗至收获期干重增加量、库干重增加量与HI密切相关。特别是在低氮条件下，高HI值对产量的决定起着重要作用。（3）对10个品种10年来穗部性状的分析表明，穗部性状对栽培年限的反应因品种而异。3个品种的穗数在10年内变化不显著，而其他品种的穗数在不同年份间变化显著。利用气象资料对后期品种穗部性状进行分析，以明确气温、光照强度等气象因子对穗部性状的影响，但未提取出影响穗部性状的气象因子。

The research was focused on the panicle characters which are important factors of sink capacity to determine rice yield. The obtained results are as follows.(1)Quantitative Trait Locus Analysis (QTL Analysis) of yield components and panicle characters was conducted with the BILs derived from BC_1F_1 of Akihikari and IRAT109. These lines were cultured in paddy field, upland field with fully irrigation and that of less irrigation in two years. QTLs of rice yield were shifted among years or cultivation conditions and they are often common in paddy and upland field with fully irrigation. QTLs of rice yield are often found in the same regions with spikelet number per panicle, which shows the importance of spikelet number per panicle to rice yield. The spikelet number per panicle was mainly affected by the numbers of differentiated spikelets and aborted spilelets before heading.(2)QTL Analysis with the same lines used in under different nitrogen fertilizer application showed that QTLs of rice yield were shifted with the amount of nitrogen fertilizer, but that they were not related with panicle characters but related strongly with harvest index (HI). Plant dry weight at heading, dry weight increase from heading to harvest and sink were closely related to the HI. Especially, under low nitrogen condition, high HI was very important to determine yield.(3)The analysis of panicle characters with 10 cultivars sampled during 10 years showed the responses of panicle characters to cultured years were different among cultivars. The panicles in 3 cultivars did not significantly change during 10 years, however in other cultivars showed significant variation among years. The panicle characters in latter cultivars were analyzed with meteorological data to clarify the effects of air temperature, light intensity and so on. However, no causal meteorological factors were extracted.