Studies On Growth Development, Physiological Characteristics And Production Of Crop Under Soil Water Stress

Water shortage is one of world difficult problem. The response of crops to water stress involves the research of highly effective water resources use, and therefore it is particularly important. Crops respond to water stress by altering their cellular metabolism and invoking various defense mechanisms. Much study had showed that there existed a phase response to water deficit, and also classified different stages. So it is very necessary to probe the changes of different physiological indicators under water stress, using the distinctive characteristics of crop in physiological water conservation and anti-drought, can result in most benefits with finite water quantity.The test in the key laboratory of agricultural soil and water engineering in arid and semiarid areas by Ministry of Education in Northwest A & F University, and select the widely cultivated in northern China winter wheat and summer maize field crops as the test material, for carry out under different water conditions, different water stress period of non-sufficient irrigation. Analysis of the winter wheat and summer maize growth and development, dry matter accumulation and distribution, yield and water use efficiency, results show that:(1)The height of plant differences between different treatments but not significantly, overall wheat height is proportional to its soil water content. Height growth of the sensitive stage of winter wheat is jointing stage, with any degree of water stress are not conducive to the growth of plant height, and with the aggravation of water stress decreased. From the entire growth period, the elongation early stress does not affect short-term height growth, mid-and late recovery of water can make it back to normal height; elongation in late to influence the critical period of water height, short Water deficit significantly reduced plant height increment. After heading, plant height of wheat does not change, irrigation of wheat elongation has no effect. Soil water stress on leaf area of winter wheat greatly, and with the intensification of water stress, the growth period appeared obviously showed regularity. Severe water stress the absolute value of leaf area is small, and the recession in the late morning, indicating water stress accelerated leaf senescence.(2)In the jointing, heading, early grain filling stage and rape stage, the treatments relative chlorophyll content of winter wheat was no significant difference. Late in grain filling, each dealing with the relative chlorophyll content of winter wheat showed a rapid decline and the various treatments showed significant differences. Description With the intensification of water stress, also will result in early leaf senescence of winter wheat. Water stress on growth, development seriously affected, the dry matter accumulation, translocation, distribution also have serious implications, it should be avoided in the production of major or even moderate water stress.(3)With the intensification of water stress, dry matter accumulation and grain yield of winter wheat were inhibited gradually increasing. The filling is the key to wheat yield growth period, when pre-drought or drought will impact on the grain filling process. This experiment showed that severe stress will significantly shorten the grain filling process, the peak than water suitable for filling low. Even if the early growth of winter wheat adequate water supply, and in the booting, heading and filling stage of any water treatment will shorten the period of the duration of grain filling, reduced number of grains, also reduced the weight, the ultimate impact of production. Therefore, early jointing stage of winter wheat may allow mild water stress, while the filling should try to avoid any degree of water stress. Water stress from the dry matter production of winter wheat and grain formation of both the material source affect its production of wheat yields. Moderate water stress at the same time after rehydration can be stored in vegetative organs to speed up the material transferred to the grain, which makes up for the decline in production. To do this properly in winter wheat growing period, desirable to reduce irrigation frequency and irrigation did not affect the production of larger, and can increase water use efficiency.(4)Maize from emergence to heading and final plant height increased day by day, and then not change during the growing plant height. Including jointing - heading for the fastest growth rate during the height of summer corn. Maize throughout the growing period, drought stress inhibit the increase of its height. Early in the fertility of soil water content has little effect on plant height, height after jointing stage of growth rate with increasing water stress the difference. Before filling in maize, stem diameter has shown a growth trend, the future filling reduced diameter did not change even slightly. Elongation of maize stem diameter is the fastest-growing period. Reduction in stem diameter with the water stress level of the strength of the trend shows synchronous changes, under drought stress than the full diameter of the small water treatment.(5)Maize in the whole growth period, every treatment the dynamic changes in leaf area per plant showed a parabolic shape, and the maximum leaf area per plant generally appear before and after flowering. Growth of the first half of the leaf area increased rapidly, half of the stable and gradually decline, and decline with increasing water stress accelerated.Maize aboveground dry weight of the whole growth period is a gradual increase in the process, regardless of how the changes in soil moisture are generally showing a "S"-type growth curve, that is, slow-fast-slow growth trend. In clover-jointing shoot dry weight increased relatively slowly; jointing-heading dry weight increase and speed up; heading-filling the dry weight increased rapidly early stage and then the trend slows; filling-maturity relatively gentle increase in mature dry remain the same or even decrease slightly. Jointing-heading and heading-filling are shoot dry weight of the water sensitive period of maize. Maize growth and development in the hot season, the whole growth of domestic demand more water, yield formation and soil water content is closely related to but not completely linear, demonstrating that the demand for maize to water have moderately boundaries. At Clover-jointing to moderate water stress, water recovery in the following growth period, not only will not cut production, but also high and even increase production, but can also play the purpose of saving water. Soil water stress on maize growth, dry matter accumulation and yield formation of a distinct stages, water stress on corn growth after the impact strength is more than half of the first half of the growth. So, the main phase of save water is in the first half of the growth of summer maize, and water management is also nto to be ignored in the half of the growth of summer maize.