Response and yield components of 54 varieties to high seeding rate planting in rapeseed(Brassica napus L.)
Planting density is one of the most important factors to improve repeseed yield,generally 30×104-45×104 plants/hm2 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/hm2.High seeding rate can produce more than 180×104 plants/hm2.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/hm2 seeding rate which simulated farmer's seeding habit.The results showed that a large range genetic variation existed in no-effc-tive 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 effec-tive 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 num-ber per silique and seed weight.Different varieties could form different effective plant density,70×104-120×104 plants/hm2 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 re-lated to early vigor,plant dry weight,seed number per silique,seed weight.
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