以水稻(Oryza sativa Linn.)的常规稻品种‘黄华占’、‘湘早籼45’和‘湘晚籼13’, 一般杂交稻品种‘金优402’和‘Ⅱ优838’, 超级杂交稻品种‘株两优819’、‘丰源优299’、‘陆两优966’和‘Y 两优1 号’为实验材料,在2008 年和2009 年不同产季,对种植于多阴雨的湖南桃源县的不同品种水稻的产量构成因子、群体性状和叶片净光合速率(Pn)差异进行了研究。结果显示:在产量构成因子方面,不同品种水稻的有效穗数、每穗粒数、结实率、千粒质量和产量均有一定差异,超级杂交稻品种的产量高于一般杂交稻及常规稻品种;其中,产量分别与有效穗数和结实率呈显著正相关(P<0. 05),与每穗粒数呈极显著正相关(P<0. 01),与千粒质量无显著相关性。在群体性状方面,不同品种水稻的株高、最大茎蘖数、最大叶面积指数(LAI)、生物量及收获指数均有一定差异,但产量分别与株高、最大LAI 和生物量呈极显著正相关,与收获指数呈显著正相关,与最大茎蘖数无显著相关性;其中,产量与最大LAI 的相关系数最大(0. 889)。在拔节期和抽穗期,各品种水稻单叶的Pn 日变化曲线呈“双峰型”,Pn 第1 个峰值差异均较小,“午休”阶段以及第2 个峰值Pn 差异增大,总体上看“午休”阶段常规稻品种的Pn 降幅明显大于杂交稻;各品种的Pn 日平均值也有明显差异,常规稻品种的Pn 日平均值总体上低于杂交稻。研究结果表明:在阴雨寡照的生态条件下超级杂交稻品种的产量高于其他类型水稻品种,其高产机制与叶面积指数的增加有关。

Taking conventional rice cultivars ‘Huanghuazhan’, ‘Xiangzaoxian 45’and ‘Xiangwanxian 13’, common hydrid rice cultivars ‘Jinyou 402’and ‘Ⅱyou 838’, and super hybrid rice cultivars ‘Zhuliangyou 819’, ‘Fengyuanyou 299’, ‘Luliangyou 966’and ‘Y liangyou No. 1’of rice (Oryza sativa Linn.) as experimental materials, variation of yield component factors, population traits and net photosynthetic rate (Pn) of leaf among different rice cultivars cultivated in a typically rainy and sunless region of Taoyuan County in Hu’nan Province was studied at different production seasons in 2008 and 2009. Results show that in respect of yield component factors, there are certain differences in number of productive ear, number of grain per ear, seed-setting rate, 1 000-grain weight and yield among different rice cultivars, and yield of super hybrid rice cultivars is higher than that of common hybrid rice and conventional rice cultivars. In which, yield has a significantly positive correlation with number of productive ear and seed-setting rate (P <0. 05), respectively, and has a very significantly positive correlation with number of grain per ear (P<0. 01), while no significantly correlation with 1 000-grain weight. In respect of population traits, plant height, maximum tiller number, maximum leaf area index (LAI), biomass and harvest index among different rice cultivars are different, but yield has a very significantly positive correlation with plant height, maximum LAI and biomass, respectively, and a significantly positive correlation with harvest index, while no significant correlation with maximum tiller number. In which, correlation coefficient between yield and maximum LAI is the highest (0. 889). In elongation and heading stages, Pn diurnal change curve of single leaf of all cultivars tested are “double- peaks” type, variation of the first peak value of Pn is smaller but that at “middle depression” and that of the second peak value of Pn among different cultivars increases. Generally, Pn reducing range of conventional rice cultivars is obviously greater than that of hybrid rice cultivars at “middle depression” There is an obvious difference in Pn daily average among different cultivars, and Pn daily average of conventional rice cultivars is generally lower than that of hybrid rice cultivars. It is suggested that under ecological condition of rainy and sunless region, yield of super rice cultivars is relatively higher than that of other type rice cultivars, and the high-yielding mechanism relates to increasing of leaf area index.