Research on the Relationship between the Development Imbalance of Wheat Ear,Spikelet and Grain and Vascular Bundle System and Its Physiological Reason

[Objective] The study aimed to know the imbalance of wheat ear,spikelet and grain development,vascular bundle system and distribution relationship of organic nutrients in organs.[Method] Before the heading of wheat,the 1st and 2nd internodes under ear were collected from the main stem,1st and 2nd tillers and the spikelet were collected from upper,middle and lower positions of ear on main stem to be used as samples to measure the areas of vascular bundle and phloem and determine the contents of soluble sugar and amino acid.[Result] All the diameters of the 1st and 2nd internodes under ear of wheat,area of basic tissue,number and area of vascular bundle and area of phloem were biggest in main stem,that of the 1st tiller were secondary and that of the 2nd tiller were smallest.The distribution of vascular bundle in the rachises of spikelet in different parts of ear had difference,and the number and area of vascular bundle leading to each flowerlet was also different in the same spikelet.During the growth course of ear,the contents of soluble sugar and amino acid changed continuously with imbalance distribution in plant and organs in ear.[Conclusion] The imbalance of wheat ear,spikelet and grain development closely related to the imbalance of the distribution of their vascular bundle.The interaction of source-sink relation and vascular bundle system led to imbalance development of each yield factor in wheat.The imbalance formed by ear organ had close relation with the difference of nutrient supplication.