Study On Heterosis In Hybrids Between Common Wheat (Triticum Aestivum L) And Wheat Lines Derived From Recurrent Selection

As one of the major crops in China ,wheat plays an important role in the food supply of the populated Country and its trade Market.Utilization of heterosis is an important and useful way to increase crops yield and improve quality . Low level of heterosis for hybrid is one of the major limitationin the commercial use of hybrid wheat. To improve heterosis level is considerated to be the main task for the Commercialization of hybrid wheat.The study was undertaken to explore heterosis in the hybrids between common wheat and wheat lines derived from recurrent selection .with the aims to broaden the genetic basis of hybrid wheat and to increase the heterosis level of hybrid wheat. At the same time.REMAP markers were used to study the relatioship between the marker-based genetic diversity and heterosis in these hybrids. The results were as follows:1. Based on two years data,higher levels of heterosis were obtained in the hybrids betweem common wheat and wheat lines derived from recurrent selection, as compared with the intervarietal hybrids. The average heterosis observed for different traits were in the following order: yield per plant(22.81%)> yield per plot(12.14%)>1000 grain weight(11.37%)>plant height(7.32%)>spikes per plant(6.65%)>grain numbers per spike(5.0%)>spike length(3.50%)>the numbers of spikelet(3.48%).2.The result of the analysis of Combining Ability shown that the General Combining Ability(GCA)were significiantly different among various Parents .The Special Combining Ability were also significantly different among different hybrid combinations.3.It was indicated that the heterosis and F1 performance of various characters were significantly correlated with the GCA effectThere would be stronger heterosis if both parents had higher GCA or the GCA of the various yieldcomponents was complementary.Some crosses had lower SCA,but still had higher heterosis.indicating that the degree of heterosis was not completely determined by SCA effects.4.The GCA variance contributed more than SCA variance to the genetics variance, suggesting that additive effect are more important.5.Five common wheat cultivars originated from different regions of China and ten wheat lines derived from recurrent selection, were used to determine the genetic diversity within and between common wheat and progeny of recurrent selection 1 wheat using wheat REMAP markers to assess the possibility of establishing new heterotic group in hybrid wheat breeding.The result shown that the Polymorphisms of REMAP markers were found to be lower in progeny of recurrentselection than that in common wheat.This is because of the close relationship among recurrent selection parent of progeny ofirecunent selection and apparently shape Characters differency among common wheat.The cluster analysis using UPGMA method indicated that REMAP marketscould be helpful in establishing wheat heterotic group.6.The relationship between genetic distance (GD) and heterosis was studied.The result showed that GD and herterosis were not correlated between progeny of recurrent selection and common wheat.Theresultshowed that the mean GD value was 0.336 within common wheat varieties. And 0.324 between common wheat and recurrent selection later generation wheat.The mean yield heterosis was 11.14% beween common wheat hybrids and 19.34% between common wheat and recurrent selection later generation wheat hybrids.