Optimization of Plant Density and Row Spacing for Mechanical Harvest in Winter Rapeseed (Brassica napus L.) Effects of Harvesting Date on Yield Loss Percentage of Mechanical Harvesting and Seed Quality in Rapeseed Effects of Paclobutrazol on Yield and Mechanical Harvest Characteristics of Winter Rapeseed with Direct Seeding Treatment Effects of Nitrogen Fertilizer and Planting Density on Yield Loss Percentage of Mechanical Harvesting in Rapeseed