种植密度对油菜机械收获关键性状的影响

油菜机械化生产中,茎秆倒伏和角果开裂是引起产量损失的主要因素。为探究密度对油菜机械化关键性状的影响,以中双11、华油杂9号为材料,设置4个密度(15万株hm~(–2)、30万株hm~(–2)、45万株hm~(–2)和60万株hm~(–2)),测定产量构成、倒伏指数及抗裂角指数相关指标。结果表明,(1)不同密度下,群体有效角果数,每角粒数差异显著,2个品种产量均在45万株hm~(–2)时最大;(2)随密度增加,油菜根颈粗变细,茎秆倒伏指数增加,增加了倒伏风险;在低密度(15万株hm~(–2)和30万株hm~(–2))下,茎秆临近冠层部位最易倒伏,在高密度(45万株hm~(–2)和60万株hm~(–2))下,茎秆中部及中部偏上部位倒伏指数较大,即与低密度相比,高密度油菜茎秆倒伏发生部位降低;(3)分枝抗裂角指数均小于主茎抗裂角指数,且随分枝高度降低呈先增加后降低趋势。不同品种油菜主茎抗裂角指数对密度响应存在差异:中双11随密度增加逐渐降低,在15万株hm~(–2)下最大,华油杂9号则随密度增大呈先增后降趋势,在30万株hm~(–2)下最大。角果发育初期至成熟期含水量下降速率与抗裂角指数极显著负相关,且相关系数最大,表明该指标是密度影响抗裂角指数的最关键因素。

Effects of Planting Density on the Mechanical Harvesting Characteristics of Semi-winter Rapeseed

Two canola varieties (Zhongshuang 11 and Huayouza 9) with four planting densities (15 × 10⁴, 30 × 10⁴, 45 × 10⁴, and 60 × 10⁴ plants ha^-1) were used to evaluate their effects on yield, lodging and pod shattering resistance index (PSRI). With the increase of plant density, effective pods per hectare increased, resulting in increasing yield. The highest yield was observed at density of 45 × 10⁴ plants ha^-1 for both of the two varieties. With the increase of plant density, the root crown diameter decreased which led lodging index to be increased. Under the densities of 15 × 10⁴ and 30 × 10⁴ plants ha^-1, the part of stem below canopy had the highest lodging index, while under the densities of 30 × 10⁴ and 45 × 10⁴ plants ha^-1, the central of stem and the upper part of middle stem had the highest lodging index, indicating that the lodging region was lower than under low plant density. The PSRI of branches was smaller than that of main stems, with a tendency of increasing firstly and then decreasing with decreasing branch height. The PSRI of main stem of the two varieties had different responses to increasing density, that was decreasing in Zhongshuang 11 while increasing firstly and then decreasing in Huayouza 9, with a highest PSRI under 300 000 plants ha^-1. The water declining rate of pod wall from early pod development to pod maturity had highly significant and negative correlation with pod shattering resistance, indicating that this index is most important for density effects on pod shattering.