油菜对超高密度直播的响应与产量构成性状分析

Response and yield components of 54 varieties to high seeding rate planting in rapeseed(Brassica napus L.)

油菜种植密度是影响群体产量最重要的因素之一,我国油菜品种区试和生产推荐的种植密度一般为30万~45万株/hm^(2),但因天气和土壤条件较差,会影响油菜出苗。长期以来,油菜种植农户形成了大幅度增加播种量的播种习惯,如湖北、湖南和江西等农户播种量达7.5 kg/hm^(2),出苗密度达到180万株/hm^(2)以上,现有品种是否适应这种超高密度种植尚不清楚。本研究参照农户种植习惯,对54个油菜品种(系)按随机区组设计,模拟生产超高密度群体,分析不同油菜品种在超高密度种植下的收获密度、主要农艺性状差异、产量及产量构成等重要性状。结果表明,超高密度直播下品种的无效单株密度、分枝角果数、有效单株密度和产量等性状遗传变异很大,其中株高、每角粒数、单株地上部重、有效单株密度与产量呈显著或极显著相关。高产品种与低产品种相比,高产品种的平均产量增产达67.6%,平均有效单株密度、单株地上部重、株高、茎粗、主花序角果数、角粒数和千粒重等性状显著或极显著提高。多元相关分析表明,有效单株密度、角粒数和单株地上部重与产量的关系达显著水平,其中有效单株密度对产量的直接作用最大,通径系数为0.6849,其次为单株地上部重、株高、角粒数和千粒重等。不同品种能形成不同的有效单株密度,当有效单株密度范围在70万~120万株/hm^(2)时单产最高,表现出较高的单产水平。为适应实际农民超高密度直播方式,建议生产上应针对性开展适应超高密度直播的品种筛选试验与示范,育种方面重点提高有效单株密度的形成能力、角粒数和角果数,加强对品种苗期生长速度、单株地上部重、角粒数、千粒重等性状选择。

Planting density is one of the most important factors to improve repeseed yield,generally 30×10^(4)-45×10^(4) plants/hm^(2) is recommended in national variety trials and farmer planting in China.However,poor weather and soil conditions will affect the emergence of rape seedlings.For a long time,rape farmers have formed the sowing habit of greatly increasing the sowing amount,for example,the sowing amount of farmers in Hubei,Hunan and Jiangxi reaches 7.5kg/hm^(2).High seeding rate can produce more than 180×10^(4) plants/hm^(2).In period of emergence,if current rapeseed varieties can adapt to high seeding rate is unclear.In this study,54 rapeseed varieties planted with 7.5 kg/hm^(2) seeding rate which simulated farmer’s seeding habit.The results showed that a large range genetic variation existed in no-effctive plant density,plant pods,effective plant density and yield.Under high seeding rate,plant height,number of seeds per silique,plant weight and effective plant density were significantly correlated with yield.Compared to the low-yield type varieties,high-yield type varieties increased 67.6%in yield.Multivariate correlation analysis showed that effective plant density,seed number per silique and plant dry weight had a significant relationship with yield,effective plant density had the largest path coefficient on yield(0.6849),followed by plant dry weight,plant height,seed number per silique and seed weight.Different varieties could form different effective plant density,70×10^(4)-120×10^(4) plants/hm^(2) effective plant density ranges would produce higher seed yield.In order to adapt to the high seeding rate,we should select suitable varieties with higher seeding rate field trial.For genetic improving and variety breeding,we should focus on the same traits such as strong forming ability of effective plant density,seed and pod number,which related to early vigor,plant dry weight,seed number per silique,seed weight.