| Wheat seedling growth plays a vital role in its development process, and many physiological traits at the seedling stage show greater genetic differences. Photosynthesis is a physiological basis for the formation of crop yield, it is important to do research in whole plant photosynthetic rate, especially in genetic mechanism of whole plan photosynthetic rate, due to a single leaf net photosynthetic rate can't be stand for the whole plant.Crop canopy structure, which affects the distribution of light at the crops and photosynthetic capacity of groups, is an important factor of determining crop yield. Suitable leaf area index and canopy structure are useful to improve photosynthetic capacity. For wheat genetic improvement, It is an important goal that according to improve population structure to make more light reach the leaves within the canopy in order to increase light interception of lower leaves.In this experiment, taking the RIL population derived from Xiaoyan54 and J411 as the materials, using the method of composite interval mapping to detect the QTLs of whole plant photosynthetic rate and canopy related traits. The main findings are as follows:1. A total of 20 QTLs of whole plant photosynthetic rate and related traits were detected, which were distributed on chromosome 2D,3B,5A,5B,5D,6A,6B,7A,7B. The traits which had a higher correlation showed a pleiotropic effect or tightly linked.In the interval between Xwms156.1 and Xwms328 on chromosome 5A, four major QTLs for fresh weight, dry weight, leaf area, whole plant photosynthetic rate explained the phenotypic variations by 16.71%,14.90%,17.75% and 11.30%,respectively, whose positive alleles were all originated from Xiaoyan54,can be used for molecular marker assisted breeding and polymerization breeding.2. In the field condition, leaf area index, mean tilt angle and diffuse non-interceptance were detected using LAI-2000 at heading stage, flowering stage and late grain filling stage, respectively. 37 QTLs were detected which were distributed on chromosome 1A,1B,1D,2A,2B,2D,3A,3B,4A,4B,4D,5B,7A and 7D. In the interval between Xwms448 and Xcfa2043 on chromosome 2A, 2 QTL controlled leaf area index of heading and flowering stage respectively, which show a higher genetic contribution and have the same genetic effect.In the interval between Xbarc140 and Xbarc142 on chromosome 5B, four QTLs controlled leaf area index and iffuse non-interceptance of heading and flowering stage, respectively. 3. LAI showed large genetic variation and exhibited continuously normal distribution in the RIL population. LAI at the heading and flowering stages was determined mostly by total stems, plant height, and third leaf length as well as by the areas and lengths of the top three leaves when controlling total stems and plant height. For RILs with higher LAI than 4.0, larger mean tilt angle at the late grain filling stage means higher biomass and grain yield. Higher ratio of the lengths between flag and second leaf may be a candidate selection index for high-yielding dwarf or semi-dwarf varieties. |
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