| Under the new situation that the irrigation water will be reduced by about 100s3million m in Hetao irrigation district, a water-saving experiment was carried out atShahaoqu experimental station in Hetao irrigation district. The American sunflower G 101 was planted in field and pot, physical and chemical index of soil (soil moisture, soil salinity), ground water table and physiological index of plant (height of plant, area of leaves, dry matter accumulation, net photosynthetic) were regularly measured. Then, effect of water stress, salt stress, and water-salt stress on crop growth, physiological process, yields formation and crop WUE were studied. The main findings are as follows:1.Different salt treatments are affected sunflower germinating time. In pot experiment, germinating time of seeds in the medium saline soil (salt content 0.31%) was two days later than that of seed in light saline soil (salt content 0.2 1%). In medium saline soil (salt content 0.43%) it was four days later than that of light saline soil (salt content 0.21%). On the 11th day after seeding, height of plants growing in the medium saline soil (salt content 0.3 1% and 0.43%) was 57.38% and 27.37% of the height of plants in light saline soil (salt content 0.2 1%) respectively.2.The result of seedling in the field showed: rate of emergence in light saline soil was 80-90%; 70-80% in medium saline soil; 3040% in heavy saline soil. So salt stress greatly affected on emergence.3.It was quite harmful to irrigate in seedling stage in saline soil. The more saline the soil, the more serious the rate of death of seedling. Therefore, it is not appropriate to irrigate during seedling stage so as to promote root growth and decease rate of death.4.The result of water stress experiment showed that appropriate soil moisture content was 75% 9 ~ during sunflower squaring period in light saline soil, but when it was over 70% 9 ~, sunflower could grow well in the late stage of growth. Height of plants under the light water stress and medium water stress were 96.23% and 95.60% of that of control groups. The area of leaves was 92.41% and 93.18% of the control groups? Yield in light water stress was 4.526t/ha less than yield of the control groups (4.6l6tlha). While in WUE, light water stress was 1.31kg/mt thecontrol groups was 1.26 kg/rn3 -The ratio of decreased output was 14.23% under the medium water stress. Heavy water stress has certain effect on the plants growth and output. Height of plants and area of leaves were 79.71% and 81.91% of the control groups? the ratio of decreased output was 19.22%.5.As for salt stress of growth stage, the results showed that growing under propriety saline soil (salt content rang from 0.2% to 0.3%), area of leaves, dry matter accumulation and weight of sunflower heads were 1.26, 1.53. 1.25 times as much as the control groups?(salt content 0.104%), except influencing to height of plants. So, it had not bad effect on sunflower growth, whereas, it can prompt the sunflower growth to some extent. While beyond 0.3%, it would be harmful to plants growth.6.When the plants experienced the difference salt stress in the total growth period, their growths difference effects. In the total growth period, medium and heavy salt stress were quite harmThl to plant growth, and the ratio of decreased output was 42.25% under the medium sale stress, yield of heavy salt stress was near 0. So, the longer time that plants experienced the salt stress; the more seriously the plants were affected.7.The result of water-salt stress showed: It did certain harm to crop growth under light water-salt stress, but the harm was little. Yield under light water-salt stress was 83.36% of the control groups? Medium water-sale stress had serious harm to plant growth and final output. The ratio of decreased output was 45.27% under medium water-salt stress. |
