Study On Agronomic Technology Of Rapeseed Production Under Direct-sowing And Mechanical Harvesting In Central Region Of Jiangsu Province

Through analyzing the yield and the yield components, dry matter production of directing-sowing rapeseed and the losses of mechanical harvesting to study the agronomic technology of rapeseed production under directing-sowing and mechanical harvesting in the central region of Jiangsu province. The main results were as follows.1. The seed yield of directing-sowing rapeseed gradually declined with the delaying of sowing date. The optimum sowing date in the central region of Jiangsu province is in the range of last two weeks of September to the 5th of October. After the harvesting of autumn ripening crops, the derect-sowing rapeseed should be sown as early as possible. Among the yield components, the pod number per mu and 1000-seed weight were reduced with the delaying of sowing date.The difference of seed number per pod among different sowing date was less. Path analysis showed that theincresing of pod number per mu was the main reason to increase seed yield.The amount of dry matter in ripening stage and harvest index (HI) were reduced with the delaying of sowing date. Path analysis showed that increasing pod shell and stem and branches weight would benefit to the increasing of seed yield.2. The seed yield of direct-sowing rapeseed increased first and then decreased as the increasing of planting density. The optimum planting density in the central region of Jiangsu province was 1.9～2.3×104 plants/ mu. More or less planting density was not good for the increasing of seed yield. Among the yield components, with the increasing of planting density, pod number per plant and seed number per pod decreased but the pod number per mu and 1000-seed weight increased at first and then reduced. Path analysis showed that, the derect path coefficient between pod number per mu, seed number per pod and 1000-seed weight and seed yield were all positive, but pod number per mu and seed number per pod and 1000-seed weight related negatively. With the increasing of planting density, the weight of pod shell and stem and branches per plant were reduced, but the weight of stem and branches per mu were increased and the weight of pod shell per mu were increased first and then decreased. Path analysis showed that the derect path coefficient between HI,weight of pod shell and weight of stem and branches and seed yield were all positive, HI and the weight of pod shell and the weight of stem and branches related negatively. Therefore, keeping appropriate pod number per mu and increasing seed number per pod, 1000-seed weight and HI were benefit to increase seed yield.3. Through measuring the loss source in the process of mechanical harvesting in rapeseed, it showed that the main loss source of mechanical harvesting in rapeseed taked place in the process of threshing and cleaning. The percentage of seed loss in the process of mechanical harvesting was the least when planting density was 2.17×104 plants/mu. The variety of rapeseed with high-yield and high-quality, less brabches, lower height and the pods ripening uniform should be the ideal one to fit mechanical harvesting.