[Effects of plastic film mulching on soil temperature and moisture and on yield formation of spring wheat].

Field experiments were carried out to study the effects of plastic film mulching on soil temperature and moisture, and on yield formation of spring wheat. The results showed that plastic film mulching could increase soil temperature with "U" variances in the whole growth period of spring wheat. Plastic film mulching could also increase soil available water by restraining evaporation and elevating deep water to the layer useable for roots. The promotion of soil temperature and soil water content under plastic film mulching was favorable to the development and water use of spring wheat in its earlier stage. Root developments were restrained when mulching in later stage of spring wheat, with decreases in crop water consumption and water use efficiency, and there was no significant effects on yield formation. The spring wheat yields under control (CK), pre-sowing irrigation (W), mulching for whole stage (M), pre-sowing irrigation adding mulching for 30 days (WM30), pre-sowing irrigation adding mulching for 60 days (WM60), and pre-sowing irrigation adding mulching for whole stage (WMw) were 2 554, 2,424, 2,750, 3,138, 3,305, and 3,123 kg.hm-2, respectively, and the optimum mulching time was at 40-60 days.