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

本研究以温敏雄性不育（TGMS） T29系为材料，与多个籼粳品种杂交，研究其光合和农艺性状的杂种优势，为栽培提供参考。（TGMS） T29在抽穗前15 ~ 11天的日平均温度为24.1℃或以上时，不育。6月16日至11月在冲绳抽穗时，由于温度超过24.1℃，花粉和小穗均完全不育。结果表明，这一时期可用于冲绳县F_1杂交种子生产。在20 ~ 35℃的温度范围内，T29系F_1的光合能力（以co2交换率（CER）计算）低于父本。而在40℃条件下，气孔导度越高，蒸腾速率越高，导致F_1杂种的CER对父本和中亲本均具有正优势。在F_1杂化中，较高的CER也可能是由于较高的非光化学猝灭。研究了TGMS系与籼粳品种杂交的5个F_1在分蘖期、花期和成熟期部分生理形态性状的杂种优势。杂种F_1在各生育期的CER均低于父本，主要原因是叶片含氮量较低。在生长季节，由于分蘖数和单株叶面积都较大，所有F_1杂种在干物质产量上均表现出高于父本和中亲本的正杂种优势值。杂种F_1在籽粒产量和穗粒数上均表现出比父本正优势。穗期干物质产量较高是F_1杂种杂种产量优势的主要原因。杂种F_1在籽粒产量上的杂种优势还表现在单株穗数较多，尤其是每穗颖花数较多。由此，本研究获得了温敏雄性不育（TGMS） T29系与多个籼粳品种杂交获得的F_1杂种优势和栽培的有效信息。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