| Lack of rainfall and its uneven distribution are main reasons to affect the efficient use of water and nutrient in soil by crops in dry land areas. Water has become the main cause of reduction of yield in this area. It is found that if a crop suffered from the drought rewatered, there would be some compensatory growth, and the yield also would have compensatory. In the same time, fertilization can play an important role in crop drought resistance and the formation of compensatory effect after rewatering. In this research, winter wheat and summer corn were selected as experimental crops. Our purpose is to investigate the sensitive period of drought resistance of the crop and the most effective period of water recovery, and their relationship with the fertilization to provide useful information for the water saving technology in agriculture in dry land areas. The main results were as follows: (1) The time and duration of water stress will affect the growth and nutrient uptake of winter wheat. In general, the adapting capacity of wheat to water stress in tillering stage was stronger than in jointing stage, so it suffered less injury. Serious water stress did more harm to wheat than middle water stress,and also showed a greater recovery in growth than middle water stress when water supply was recovered. At tillering stage, the ratio of root/shoot was higher than that at jointing stage, which was one of the most important reasons that wheat had a strong drought resistance capacity at tillering stage. After rewatering, the growth rate of overground part was faster the root, therefore,the ratio of root / shoot decreased；the increase of water consumption was greater than dry matter when rewatering, therefore, its water use efficiency (WUE) declines.(2) At tillering stage, water stress had limited effects on wheat dry matter production when the soil fertility was high. During the jointing stage, the grain and total dry matter production was increased when water was supplied again. In addition, fertilization reduced the stomatal conductance and the rate of transpiration of winter wheat, so water dissipation was reduced. Under the condition of middle water stress, fertilization improved the water use efficiency of winter wheat.(3) Water stress restrained the growth of summer corn,and serious water stress had a more significant influence to corn than the middle water stress. In prophase of seeding stage, water played a more important role than anaphase of seeding stage. Soil water condition influenced the uptake of nutrient in soil, the order of influence degree was phosphorus>nitrogen>potassium. Water use efficiency was the highest under of the condition of full water supply. In anaphase of seeding stage, the WUE was in a relative high level. When water supply was recovered, the injury of middle stress in prophase of seeding stage and serious in anaphase of seeding stage was recovered significantly. (4) High level nitrogen treatment could play some action in improving the water status of injured corn in prophase of seeding stage, but it had little effect in anaphase of seeding stage. Fertilization reduced the stomatal conductance and the rate of transpiration of summer corn,therefore,water was saved.(5) In the angle of trends of corn growth under water stress and rewatering condition, treatments of 5 days water stress recovered growth in a short time, treatments of 10 days stress recovered slowly, but they kept the increasing for a long time；finally, they catched up with the treatments of 5 days stress. No matter what water condition, the ratio of root/shoot declined along with corn growth. After rewatered, it showed an obvious trend of decreasing. On the contrary, the treatments of full water supplied showed a little decrease. With corn growth, WUE was increased; it increases fast in prophase and slower in anaphase of seeding stage. After water recovery, WUE of corn showed the same trends with the treatments of full water supplied.(6) It seems that nitrogen treatment has no significant effect o... |
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