| Salt accumulation and drought stress during growth period are the main limiting factors affecting the further improving of oil sunflower yield in saline-sodic soils. Aiming at the problems of safe utilization of saline water in saline-sodic soils of Yellow River Irrigation Area, field experiments were conducted in saline-sodic soils in Xidatan, Pingluo county, Ningxia, northwest China. Taking oil sunflower as the research object, drip irrigation under mulch as irrigation method, the experiments included different irrigation water quality treatments and different patterns of plastic film mulching. In order to find the optimal planting pattern to satisfy plant growth and to ensure high yield, water and salt characteristics of saline-sodic soils, growth and yield indexes of oil sunflower were investigated. The experiment results could provide a viable theoretical basis for amelioration of saline-sodic soils via planting oil sunflower. The main conclusions are as follows:1. Drip irrigation under mulch with saline water of low salinity could improve the soil water and salt characteristics. In surface layer, soil water content increased, and electrical conductivity (EC) decreased significantly. With the increase of irrigation water salinity, soil water content in0-20cm first increased and then decreased, while that in20-60cm decreased all along. This was directly related to the water absorption of crop root and the soil permeability.2. Plastic film mulching had the obvious effectiveness on water retention and salt restraining in saline-sodic soils. The soil water content under black plastic film was higher than that under colorless plastic film, but the salt restraining effectiveness of black plastic film was relatively poor. As the thickness of plastic film increased, water retention capacity and salt restraining effectiveness strengthened.3. With the increase of irrigation water salinity, dry matter accumulation of plant root, stem, leaf and flower all increased, no matter under mulching or not, while the different proportions of different parts in total dry matter were found among different treatments. Drip irrigation with saline water of high salinity inhibited the plant height, yield and related indexes, while the indexes above were improved under drip irrigation with saline water of low salinity.4. Plastic film mulching could increase the growth and yield of oil sunflower. Compared with those under colorless plastic film, the plant height and stem diameter were improved under black plastic film, resulting in the longer growth period of oil sunflower, demonstrated by that the yield increased by487and55lkg/hm2respectively, under black plastic film with0.004mm and0.008mm thickness. The results indicated that the temperature-raising and water-conservation effects of black plastic film was more suitable for the growth of oil sunflower.5. Correlation analysis between the soil water and salt characteristics and the growth and yield indexes of oil sunflower showed that the growth and yield indexes of oil sunflower were significantly negatively correlated with the soil EC, and moreover, the absolute value of correlation coefficient decreased with the increase of soil depth, indicating that the soil salt content in top layer had greater impact on the growth of sunflower. Significantly positive correlations between the growth and yield indexes of oil sunflower and the soil water content in40-60cm were found, indicating that the soil water content in this layer could more directly reflect the soil permeability and structural conditions. |
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