不同密度下越冬型黑麦产量形成的光合特性差异

Effect of planting density on photosynthetic performance and yield of winter rye

为了探究寒地冬黑麦饲草群体产量形成的光合特性差异,以东农冬黑麦001为材料,采取完全随机设计,设置基本苗为225×10~4株·hm^(-2)(D_1)、275×10~4株·hm^(-2)(D_2)、325×10~4株·hm^(-2)(D_3)、375×10~4株·hm^(-2)(D_4)和425×10~4株·hm^(-2)(D_5)5个密度处理,对比分析各处理主要生育阶段叶绿素含量、光合参数、叶绿素荧光参数的动态变化过程以及产量的差异。结果表明,黑麦整体叶片叶绿素相对含量在抽穗期达到最大,显著高于其他生育时期,随着密度的增高,叶绿素相对含量减少,花后叶绿素含量SPAD值下降幅度随着密度的增大而增加;各密度黑麦叶片净光合速率、气孔导度、蒸腾速率、胞间二氧化碳浓度均在开花期达到最大,显著高于其他生育时期。随着密度的增大,光合参数逐渐减小、最大光化学效率(F_v/F_m)、实际光化学效率(Φ_(PSⅡ))和光化学淬灭系数(qP)逐渐减小,而非光化学淬灭系数(qN)呈增大的趋势。研究得出,越冬型黑麦鲜草产量与干草产量在基本苗为275×10~4株·hm^(-2)时最大,随着密度的增加,黑麦生物产量逐渐降低。表明构建合理群体大小,获得较高花前光合生产能力,是获得寒地冬黑麦高产的基础。

This experiment aimed to explore the relationship between plant population density and photosynthetic performance and yield of winter rye in a cold region.The variety used was‘Dongnong winter rye 001’,and the experiment comprised 5replicates sowing densities(D1,225×104 plants·ha-1;D2,275×104 plants·ha-1;D3,325×104 plants·ha-1;D4,375×104 plants·ha-1;D5,425×104 plants·ha-1),arranged in a completely random design.Leaf chlorophyll content measured using a SPAD meter(CCM-200+)reached the maximum at the heading stage.With increased crop density,the SPAD value decreased,and the density-induced decrease was more pronounced after anthesis.The maximum values of net photosynthetic rate,stomatal conductance,transpiration rate and intercellular carbon dioxide concentration of rye leaves occurred at the flowering stage.With increasing crop density,many photosynthetic parameters,including the maximum photochemical efficiency(Fv/Fm),the actual photochemical efficiency(ΦPSⅡ)and the photochemical quenching coefficient(qP)showed progressive reduction;however,the non-photochemical quenching coefficient(qN)increased.The yield of fresh and hay winter rye(Secale)were highest at D3,after which the biomass yield decreased with increasing density.It is concluded that establishing the correct population density(D2)to obtain higher photosynthetic capacity before flowering is the basis for obtaining high yield of winter rye in cold regions.