| Serious lack of the water resources had become the importance factor that will influence the development of society, economy and entironment. This project research how to execution of water-saving irrigation and prevention saline soil at the same time in Hetao Irrigation District in the Inner Mongolia in the western of China, the oil sunflower which native main crop ( Helianthus annuus L.) was planted in the field and pot, growth process of sunflower was studied under different water-salt stress condition through insufficient irrigation under different saline soil. We investigated crop response to water-salt stress regularity through growth and physiological index of plant (height of plant, dry matter accumulation, index of leaves, leaf potential, photosynthesis and yield) on the base of statistical analysis, the relation between photosynthetic rate and its factors was analyzed by the correlation analysis and path analysis. On the basis of this, import the model of SWAP to seek after the regulation of sunflower evapo-transpiration under difference water-salt stress, established a model of crop response to water-salt stress that import the factor of salt stress through consult in common use the model of crop to water.The effect of germinating time and rate emergence are different in soil with different salt content. No effect of germinating time and rate emergence in the light and middle saline soil, and limited seriously in heavy saline soil, 2~5 days later than that of seed in light and middle saline soil. Seed could not germinate while salt content exceed 0.8% in the soil.It has different response to salt content during the difference growth stage. It is sensitive to salt in seeding stage, the physiological indexes of crop is respondent to salt obviously. Ability of tolerance salt is increased during squaring period, compensate growth is showed for the effect of seeding period. A little compensate growth or no compensate growth in the same condition and it will increase growth gap of crop with other treatments if exceeding 0.5% salt content. It will restrain growth of sunflower and decrease yield of 45.52% while exceeding 0.5% salt content in the total growth stage. Under field conditions, the sunflower grown in different salt level was studied to photosynthetic rate (Pn) and its influence factors during squaring stage in saline soil. The project is supported by National Natural Science Fund (No. 50269002).Diurnal changes of Pn and its major factors in modified light intensity and temperature measured respectively with LI-6400. The results indicated that the Pn of three treatments varied as a single-peaked curve and was decreased while salt content increasing. Under difference salt stress, difference response on high temperature and strong light of sunflower leaf. No effect of photosynthetic rate on difference treatments under the change of PAR, but distinct effect of photosynthetic rate under the change of temperature. The relation between photosynthetic rate and its factors was analyzed by the correlation analysis and path analysis. The results indicated that under difference salt stress, difference factors decreased photosynthetic rate. PAR was not major effect factor to Pn. Pn was controlled by the stomata factor in light salt stress (0.29%). Stomata, stomata and non-stomata factors were controlled mutually while the middle salt stress (0.39%). Under the high salt stress (0.68%), it was controlled by non-stomata factor and stomata and non-stomata factors were controlled mutually.Index of leaves, leaf potential and yield was decreased while soil salinity increasing. In the difference water-salt treatment, it is feasible while soil salinity is 0.2-0.3% and soil moisture is (55~65%)θfc. It did certain harm to crop growth under soil moisture is(65~75%)θfc and soil salinity is 0.3-0.5%, but the harm was little. Index of leaves, leaf potential and yield was 5.90%, 0.27MPa, and 5.92% of the light salt stress respectively. But when soil salinity >0.5%, although high water treatment (soil moisture...
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