Physio-norphological Studies For F1 Hybrid Rice (Oryza sativa L) Using Japonica-Indica Cross

本研究旨在探讨水稻光合作用及农艺性状的杂种优势，为杂交一代利用温敏核不育系T29与多个水稻品种杂交制种提供栽培依据。温敏核不育系T29在抽穗前15~11d的日平均气温为24.1℃或以上时为不育系。6月16日至11月在冲绳抽穗时，由于气温超过24.1GMT，花粉和小穗均完全不育。在20~35℃的温度范围内，T29系杂交F_1代的光合作用能力低于父本。相反，在40℃时，蒸腾速率越高，气孔导度越高，与父本和…相比，气孔导度越高，杂种优势值越大F_1代CER的亲本偏多。F_1代较高的CER也可能与较高的非光化学猝灭有关。利用水稻温敏核不育系与水稻品种杂交的5个F_1代，在分蘖盛期、开花期和面团成熟期研究了部分生理形态性状的杂种优势。大多数F_1代的CER在各个时期都低于各自的父本，主要是由于叶片含氮量较低所致。在整个生育期内，由于分蘖数和单株叶面积的增加，所有F_1代的干物质生产都比父本和中亲表现出正的杂种优势。F_1代在产量和每穗颖花数上均表现出较父本正的优势值。穗部分化期干物质产量较高是杂种F_1籽粒产量优势的原因。F_1代的产量优势主要是由于其单株穗数较多，特别是每穗粒数较多所致。因此，本研究为利用温敏核不育系T29与多个水稻品种杂交制种的杂种优势及栽培技术提供了有效的信息。较少

This study was carried out to investigate the heterosis for photosynthetic and agronomic charactes, and provide information regarding to cultivation in F_1 hybrid rice produced by crossing a thermo-sensitive genic male sterile (TGMS) T29 line with several indica and japonica cultivers. The (TGMS) T29 line was sterile when exposed to daily mean temperatures of 24.1℃ or above during the stage from 15-11 days before heading. It was completry sterile for both pollen and spikelet when the plant headed from June 16 to November in Okinawa, because the temperature exceeded 24.1℃. The fact indicates that it can be used for F_1 hybrid seed production during this period in Okinawa.Within a temperature range of 20-35℃, photosynthetic ability in term of CO_2 exchange rate (CER) in the F_1 hybrid from the T29 line was lower than the male parent. On the contrary at 40℃, a higher stomatal conductance according to higher transpiration rate was cause of positive heterosis value over both male parent and … More mid-parent for CER in the F_1 hybrid. The higher CER in the F_1 hybrid might be also due to a higher non-photochemical quenching.Heterosis for some physio-morphological characters were investigated in five F_1 hybrids between the TGMS line with indica and japonica cultivars at the active tilllering, flowereing and dough-ripe stages. CER was lower in most F_1 hybrids than in their respective male parent at all stages, mainly due to the lower leaf nitrogen content. During the growing season, a positive heterosis value over the male parent and mid-parent for dry matter production was observed in all F_1 hybrids due to both the larger number of tiller and the larger leaf area per plant. Most F_1 hybrids showed positive heterosis value over the male parent for grain yield and the number of spikelets per panicle. The higher dry matter production at the panicle initiation stage contributed to the heterosis for grain yield in F_1 hybrids. The heterosis for grain yield in the F_1 hybrids also due to the larger number of panicles per plant and especially the larger number of spikelets per panicle.Thus, the effective information regarding to heterosis and cultivation in F_1 hybrid rice produced by crossing a thermo-sensitive genic male sterile (TGMS) T29 line with several indica and japonica cultivers was attained in this studies. Less