Abstract:

To reveal the effects of chilling at the booting stage on rice dry matter production, 30 main rice cultivars (lines) in Heilongjiang Province were selected and subjected to chilling stress (17°C cold water irrigation) for 20 days. The results showed that the filled grain number per hill, seed setting rate, 1000-grain weight, and grain yield of all cultivars decreased under cold water irrigation at booting stage. The materials were classified as grades 1, 3, 5, 7 and 9 according to relative seed setting rate. Most of them belonged to grades 7 and 9, accounting for 30% of the total, while the fewest cultivars belonged to grade 1, occupying 10%. The cold water stress decreased dry matter accumulation from heading to maturity and its ratio, crop growth rate, net assimilation rate, filled grain number per square centimeter leaf area, harvest index, leaf area index, leaf basic angle of flag leaf, drooping angle of flag leaf, drooping angle of second leaf from top, drooping angle of third leaf from top. However, the cold water stress increased the ratio of leaf area of top three leaves. The correlation analysis results showed that the relative seed setting rate was significantly positively correlated with the cold water response indices(CRI) of harvest index after heading(r=0.96^**), grain yield(r=0.91^**),filled grain number per square centimeter leaf area(r=0.84^**), and dry matter accumulation(r=0.48^**); this rate was also positively correlated with the CRI of crop growth rate(r=0.44^*), net assimilation rate(r=0.44^*), and ratio of dry matter accumulation from heading to maturity(r=0.43^*). In conclusion, the reduction of rice dry matter production under cold water stress during early grain filling largely varied with rice cultivar. The cold tolerant germplasm was insensitive to cold water stress in dry matter accumulation, ratio of dry matter accumulation from heading to maturity, crop growth rate, net assimilation, filled grain number per square centimeter leaf area, harvest index after heading, which might be attributed to its important morphological specificity and physiological mechanism in maintaining grain yield under cold water stress at the booting stage.

Key words: rice in cold area, yield, relative seed setting rate, cold water stress, dry matter production

摘要：

以黑龙江省30份主栽水稻品种或品系为试材,在孕穗期设置17℃冷水灌溉处理(20 d),以常规栽培管理为对照,分析冷水胁迫对水稻干物质生产的影响。结果表明,冷水胁迫导致所有试材每穴实粒数、结实率、千粒重和产量下降,并根据相对结实率将试材耐冷性分为1、3、5、7和9级,以7和9级最多,1级最少,分别占总材料的30%和10%。在冷水处理下,全部材料抽穗期至成熟期干物质积累量及比例、群体生长率、净同化率、粒叶比、收获指数、叶面积指数、剑叶叶基角、剑叶和倒2叶与倒3叶披垂度均下降,但高效叶面积率增加。相关分析表明,冷水处理的相对结实率与收获指数(r=0.96^**)、产量 (r=0.91^**)、粒叶比(r=0.84^**)和干物质积累量(r=0.48^**)的冷水反应指数(CRI)呈极显著正相关,与群体生长率(r=0.44^*)、净同化率(r=0.44^*)和干物质积累比例(r=0.43^*)的CRI显著正相关。综上,孕穗期冷水胁迫对水稻干物质生产的影响在品种间存在很大差异,在冷水胁迫下耐冷性极强品种(系)干物质积累量及比例、群体生长率、净同化率、粒叶比和收获指数对冷水反应迟钝,这是耐冷性极强品种(系)保持较高产量的重要形态特征和生理原因。

关键词: 寒地水稻, 产量, 相对结实率, 冷水胁迫, 干物质生产