| In the study ten parents with special traits each of common wheat and forty- five F1 derived from 10×10 complete diallel crossing system and the check Shan229 were selected for the research on analysis heterosis, path between spike characteristic and yield components, parent-offspring correlation and regression ,combining ability and so on; the results were as follows; Studying on 15 agronomic characters except kernels per head which performed negative mid-parent heterosis showed positive mid-parent heterosis, the length of head and all spikelets showed significant better-parent heterosis and better-ck heterosis, plant height showed better parent heterosis and did not show better -ck heterosis. The combining model of crosses with high heterosis derived from multiple spikes type and early maturity heavy-spike type in the GuanZhong of shaanxi. Among yield components the heterosis of 1000 kernel weight was the highest, the number of spikes proved to be higher and the number of kernels per spike showed negative mid-parent heterosis .Accounting crosses with heterosis over ten percent, the heterosis of the number of spikes proved to be important among yield components, but we did not ignore the heterosis of 1000 kernel weight.By means of path analysis it was showed that the direct effect and all influence of the number of spike which affected the yield were the biggest . The direct effect of 1000 kernel weight which affected the yield was 0.776733 .Because there existed the complex interaction among spike characteristics, so it affected the yield negatively .1000 kernel weight,the number of kernels per spike and the number of spikes were very important to enhancing the yield At the same time , effective spikelets per spike and all spikelets had a certain influence on yield.Simply correlative analysis for the yield ,other spike factors and other agronomic characters showed that plant height was positively highly significant with 1000 kernel weight but it was negatively highly significant with the number of spikes .The length of ear stem was positively highly significant with the kernels per spike .All spikelets was positively correlated with yield , flag leaf area was positively significant correlated with the kernels per spike.The parent-offspring correlation and regression of point sampling yield and economic index were not significant The parent-offspring correlation and regression of all spikelets, the number of spikes,1000 kernels weight,the length of spike,the kernels per spike,effective spikelets per spike,plant length,crown leaf area,the length of ear stem ,flag leaf area ,the width and length of flag leaf, the length of flag leaf sheath and the date of heading were positively highly significant ,so it may predict the performance of F1 generation according to the mean of parent。The heterosis of F1 generation varied according to parent show .The effected which all parents affect F1 heterosis was not same .The high parent of all spikelet, the length of flag leaf the number of spikes, the width of the flag leaf had a greater influence on F1generation The low parent of 1000kernels weigh,the length of spike, the height of plant,crown flag area, the length of ear stem ,effective spikelets flag leaf area and the length of flag leaf sheath had a great influence on F1 generation. By means of combining ability ,it was showed that: The general combining ability between various parents of the same character or various characters of the same parent had significant difference as well as the special combining ability between crosses of the same character or various characters of the same parent .The GCA of parental yield and the SCA of crosses yield were relative to the GCA and SCA of yield components. Heterosis was relative to GCA, the Heterosis was most significantly and positively correlated with the SCA .So, in the basis of highly general combining ability ,selecting highly special combining ability easily gained crosses with high heterosis .The relative coefficient... |
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