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Wheat ( Triticum aestivum L. ) is one of the most widely planted and distributed crops in the word, it is also an important crop in our country. Grain filling stage is an important period in course of yield formation, which is chiefly derived from photosynthesis assimilating products of functional leaves. The size of wheat sink have a significant impact on the physiological function and senescence of leaves, large sink needs more photosynthesis assimilating products to fill, resulting in leaf assimilation product scarcity, which caused accelerated leaves senescence. Small needs less photosynthesis assimilating products, stem and leaf organs have enough assimilating products, so delayed leaf senescence..However, after the excessive ear removal, deep intensify Source-sink contradictions, caused top 3 leaves different responses. The thesis through excessive ear removal (3/4 ear removal), study on different reactions of functional leaves (top 3 leaves ) of wheat, in order to reveal the essence of color inversion phenomenon, and further improve the interaction of wheat source-sink relations theory. Through research, the main conclusions are as follows:1. Through excessive ear removal, resulting in wheat top 3 leaves color inversion phenomenon. That is in the late of grain filing stage, the green of the flag leaf is lighter to the second leaf, the green of the second leaf is lighter to the third leaf. Or both of the flag leaf and the third leaf are lighter to the second leaf. The frequency of color inversion phenomenon exist significant differences between different varieties.2. The physiological function of the color inversion plant functional leaves have also inverted. Both the chlorophyll content, photosynthetic rate, the MDA content, and the catalase(CAT) activities of the fiag leaf are under the second leaf and the third leaf, showed that excessive ear removal accelerated flag leaf senescence.3. After excessive ear removal, the physiological characteristics of different wheat varieties of functional leaves have changed. Compared with control,functional leaf dry matter, water content, soluble sugar content and solvable protein content increased after ear removal; The starch content in flag leaf and top 2nd leaf increased,and the starch content in top 3rd leaf reduced; The MDA content in flag leaf increased,and MDA content in top 2nd leaf and top 3rd leaf reduced. The catalase(CAT) activities in flag leaf reduced, and catalase(CAT) activities in top 2nd leaf and top 3rd leaf increased. 4. Excessive ear removal has significant affected on wheat seeds growth and development of different varieties. Compared with control, in the late of grain filing stage, the grain dry weight, volume, water content, soluble sugar content, starch and solvable protein content increased after ear removal in 9430. The grain dry weight, water content and solvable protein content of xiaoyan 6 are lower than those of control. The volume is higher than that of control. Soluble sugar and starch content is no less than with the control. The grain dry weight, volume, water content, soluble sugar content, starch and solvable protein content of TU2 have a slight increase than the control.
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