| To reveal deeply the effect of fluctuated soil water on the self-adapting and self-adjust mechanism of winter wheat, the dissertation studies that fluctuated soil water affected on growth of root and shoot and their relation on the whole plant level. On the basis of this, a dynamic simulation model for growth of root and shoot was established according to the theory of system dynamics; and it was made to qualitative analysis. The qualitative analysis indicates dynamic characteristics of root and shoot in the whole growth process.Two-year greenhouse experiment data, including 1999's pipe experiment and 2000 's pot experiment, were used in this study. The conclusion is summarized as follows:1. In different soil water content condition, the total trends of dry weight accumulation of root and shoot does not change. Their growth law is from slow to fast, to slow again. With soil water content fluctuating, the gradient of the growth trends line is different, which lead to difference of appearance time and standing time of maximal root weight.2. The effects of water stress on root and shoot may be attributed to three aspects. The three facts, which are a formed basis in previous stage, the after-effect of water condition before this stage and influence of water in this stage, lead to the character of root and shoot in any growth stage.3. The response of root and shoot to different water condition in seedling stage, in tilling stage and in jointing stage expresses: it is beneficial to root and shoot of winter wheat to suitable deficit water before tilling stage and well water in jointing stage. While water stress took place in tilling stage and in jointing stage and adequate water was supplied in seedling stage, this treatment prevented root growth in production stage and strengthened competition between root and shoot for assimilation. The results caused that shoots growth was restricted in reproduction stage when well water was given again.4. The effect of water stress treatments that began in different growth stage and continued same growth stage on root and shoot shows: the earlier stress happens in stress stage, the smaller root and shoot are restrained, and it does not obviously decline growth rate of root and that of shoot. After the stress is released, except that a severe stress treatment is in jointing stage, compensating growth of any other treatments reduces when stress treatment happens lately. For the maximal root weight in the whole growth stage, those of mild stress treatments are larger than those of severe stress treatments, those of short-time stress treatment are larger than those of long-time stress treatments. Standing time of maximal root weight in the mild stress treatments are larger than those in severe stress treatments. This made shoot weight have the following results in ripening stage, those of short-time stress treatments are larger than that of long-time stress treatment, and that of mild stress treatments are larger than those of severe stress treatments.5. During the period of water stress, stress intensity of root and that of shoot increase with later stress happening. The intensity of shoot is larger than that of root. Comparing all kinds of treatments, intensity of root and that of shoot indicate that shoot and root in jointing stage are most sensitive to fluctuated soil water. When water stress is relieved, as for stress intensity of after-effect of soil water stress on root growth, that of short-time stress is larger than that of long-time stress; as for stress intensity of after-effect of soil water stress on shoot growth, the later stress happens, the larger stress intensity is. After-effect of stress that took place from jointing stage is maximal.6. The effect of water stress treatment that began in same growth stage and ended in different growth stage on relation of root and shoot shows: percentage of root weight gets larger and that of shootweight gets smaller with the stress degree increasing during the stress period.
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