Factors Affecting Seeding Emergence in Winter Wheat under Different Tillage Patterns with Maize Stalk Mulching Returned to the Field Studies on the Correlative Factors for Normal Seedling Development inImmature Embryo Culture of Ultra-early Maturing Nectarine Studies on the Correlative Factors for Normal Seedling Development inImmature Embryo Culture of Ultra-early Maturing Nectarine Influence of Environmental Factors on Seed Germination and Seedling Formation of Primula filchnerae EFFECTS OF ~(60)Co γ-RAYS RADIATION ON BIOLOGICAL CHARACTERS OF Platanus acerifolia Willd.SEED AND SEEDLINGS