播种量对双季稻套播油菜群体生长的影响

为研究稻田三熟制双季稻套播油菜高产栽培技术，筛选适宜的播种量，2016-2017年以丰油730油菜品种为材料，设置3.75kg /hm2、4.50kg /hm2、5.25kg /hm2、6.00kg /hm2和6.75kg/hm2 5个播种量处理，采用大田试验，比较不同播种量对双季稻套播油菜生育进程、密度、成苗率、成株率、个体生长发育、抗病性、产量及产量构成的影响。结果发现：（1）套播油菜密度随着播种量增加而增加，但成苗率和成株率随着播种量的增加而下降。（2）播种量显著影响套播油菜个体生长发育，油菜总叶数、绿叶数、最大叶片叶长和叶宽、根颈粗、单株干重等个体指标随播种量增加而下降，叶面积指数和群体干重等群体指标随着播种量的增加表现先增加后逐渐下降的趋势，以播种量5.25 kg /hm2处理叶面积指数和群体干重最大。（3）菌核病发病率和病情指数均随着播种量的增加而增加。播种量6.75kg/hm2处理比播种量3.75kg/hm2处理发病率和病情指数分别增加了19.83%和9.92%。（4）播种量与分枝高度极显著正相关，与株高、一次分枝数、单株角果数、每角粒数达到极显著负相关水平。（5）产量随着播种量的增加表现出先增加后下降趋势，播种量5.25 kg /hm2处理产量最高，显著高于3.75和4.50kg /hm2的处理，分别增产16.72%和9.36%。可见播种量不足或过大均不利于套播油菜高产群体的构建，本区域内稻田三熟制双季稻套播油菜适宜播种量为5.25~6.00 kg /hm2。

Effect of sowing rate on population growth of interplanting rapeseed in double-cropping rice

To find out proper sowing rate of interplanting rapeseed in double-cropping rice, rapeseed cultivar Fengyou 730 was used in field during 2016 to 2017. Five sowing rates (3.75, 4.50, 5.25, 6.00 and 6.75 kg/hm2) were designed. The effect of different rates on rapeseed were investigated, including growth processes, density, seedling rate, mature plant rate, individual growth-development, disease resistance, yield and yield components. Results showed that seedling rate and mature plant rate decreased with the higher sowing rate. Individual growth was significantly affected. Traits of total leaves, green leaves, maximum leaf length, maximum leaf width, crown diameter, dry matter weight per plant, were decreased with the higher sowing rate. While leaf area index and dry matter weight of population increased at the beginning, and then decreased with the higher sowing rate. The leaf area and population dry weight reached their peaks at the rate of 5.25 kg/hm2. Sclerotinia disease incidence and index increased with the higher sowing rate. Compared with the rate of 3.75kg/hm2 (Q1), the disease incidence and disease index at the rate of 6.75 kg/hm2 (Q5) increased by 19.83% and 9.92% respectively. Sowing rate had significantly positive correlation with first branch height, and had significantly negative correlation with plant height, first branch number, pods per plant and seed number per pod. Yield increased with sowing rate at the beginning, but then decreased. The highest yield was obtained at the rate of 5.25kg/hm2 (Q3) treatment. It indicated that neither higher nor lower sowing rate were recommended for high-yielding population construction. In this study, the rates between 5.25 to 6.00 kg/hm2 were optimal for high yield of interplanting rapeseed in double-cropping rice in southern triple cropping system.