播种量对北方寒地旱直播粳稻产量和光合特性的影响

以粳稻品种吉隆868和通禾833为供试材料,研究在旱直播条件下播种量对产量、干物质积累与分配以及光合特性的影响。结果表明,水稻产量随播种量的增加呈先增后减趋势,吉隆868和通禾833的最高产量分别出现在播种量为180万和150万粒/hm ²;随播种量增加,有效穗数先增后减,每穗颖花数和每穗成粒数均减少,千粒重变化不大。在拔节期两品种茎蘖数均随着播种量的增加而增大。产量达到最高时,不仅成熟期单茎和群体干物质积累量最大,且抽穗期-成熟期的干物质积累量和群体生产率也最高。剑叶和倒二叶的叶绿素含量和净光合速率均随着播种量的增大而减小。研究表明通过控制播种量保证足够的基本苗数,既可以优化群体结构又可以提高光合效率,从而获得高产。

Effects of Sowing Rate on Yield and Photosynthetic Characteristics of Drill-Seeded Japonica Rice in North Cold Region

In order to study the effects of sowing rate of drill-seeded rice on yield, dry matter accumulation and distribution, and photosynthetic characteristics, a field experiment was conducted with conventional japonica rice varieties Jilong 868 and Tonghe 833. The results showed that, the yield appeared a trend of first increasing and then decreasing with the increase of sowing rate. For the highest yield of Jilong 868 and Tonghe 833, the seeding rates were 1.5×10 ⁶/hm ² and 1.2×10 ⁶/hm ², respectively. With the increase of sowing rate, the effective panicles increased firstly and then decreased, total flowers and grains per panicle were reduced, while 1000-grain weight changed little. The number of main stems and tillers of two varieties at jointing stage increased as the sowing rates increased. When the yield reached the maximum level, dry matter accumulation of both single culm and population dry matter accumulation at maturity reached the highest value and also the dry matter accumulation and population growth rate from heading to maturity were the highest. As sowing rate increased, the SPAD of flag leaf and reciprocal second leaf, net photosynthetic rate declined. The results showed that the controlling the sowing rate to ensure adequate planting density not only could optimize the population structure, but also improve photosynthetic efficiency, and achieve higher yield.