种植密度对适宜机械化栽培高粱品种产量及生理特性的影响

Effects of Planting Density on Yield and Physiological Characteristics of Sorghum Hybrids Suitable for Mechenization

以适宜机械化种植的高粱品种辽杂37和晋杂34为试验材料，分别对6个密度处理的产量、产量构成因素、叶面积指数、叶绿素含量、光合速率及群体透光率进行了测定与分析。结果表明：辽杂37和晋杂34均在密度为13.5万株/hm2时产量最高，分别可达10 551.0和10 324.5kg/hm2。其中辽杂37在12.0万~15.0万株/hm2、晋杂34在12.0万~13.5万株/hm2密度时穗数、穗粒数和穗粒重协调效果较好，可保持较高产量水平。当密度达到15.0万株/hm2时，随着密度的继续增加将导致群体光合速率和透光率大幅度下降，影响干物质积累和产量形成。

MicroRNA （miRNA） is a class of endogenous small molecule non-coding RNA with length about 20- 24bp, which widely exists in eukaryotes. The mature miRNA is bound to complementary loci of target genes, regulates negatively the expression of target gene, and involves in plant growth and development, signal transduction and stress response. In this paper, the advanced progress about the effects and regulationary mechanisms of miRNA were reviewed under biotic stresses and abiotic stresses （including heavy metals, drought, low temperature, salt, and heat）, and the problems and the research in the future are suggested.