Heterosis Comparison In Five Hybrids Of Strong Heterosis Upland Cotton

Hybrid cotton can significantly improve the yield,moderately improve quality, increase resistance,which can create significant economic and social benefits.Some studies indicated that the F₂ of cotton still has heterosis to be used,which means that the cost of seed production can be greatly reduced.In this study,vigorous hybrids of upland cotton ZMS29,ZMS46,ZMS48,LMY15 and XZM2 and their respective parents were used as materials,constructed LMY15 F₂ population and analysed the yield,quality and the mid-parent heterosis of the five hybrids,compared the size of heterosis recession in different hybrids F₂,F₃ generations and constructed a primary molecular marker linkage map of LMY15,The results were as follows:1.Hybrid cotton F₁ showed heterosis in various degrees in the growth traits,the yield and the fiber quality.Heterosis over the mid-parent value was much higher than the over-parent value.On the growth traits,plant height and the number of boll branch had higher mid-parent heterosis and over-parent heterosis.The boll number had positive mid-parent heterosis and negative over-parent heterosis.In the output character,heterosis of the lint yield＞seed cotten yield＞boll number＞lint percentage＞boll size＞The fiber quality heterosis of strength＞length＞micronaire＞elongation ratio＞uniformity.2.Cotton yield heterosis was significantly and changed with the various varieties. The cotton yield mid-parent heterosis and over-parent heterosis of LMY15 was maximum. In cotton yield components,boll number far exceeded lint percentage and fruit branch number,was the most important factor which affect the yield heterosis of hybrid cotton. Cotton fiber quality inherited stably by cross from generation to generation,lied between parents,slightly better than mid-parent values.There were a certain degree mid-heterosis in XZM2 and LMY15 fiber quality.In general terms,the heterosis of LMY15 was the highest and the heterosis of ZMS48 was the weakest3.Cotton fiber quality hybrid inherited stably by cross from generation to generation, self cross recession was not obvious.The yield heterosis of the five vigorous hybrids cotton had significant recession,which was more than 50%of the theoretical value.Five F₁ hybrids mid-parent heterosis was 46.5%,F₂ mid-parent heterosis was 19.2%,F₃ mid-parent heterosis was negative.F₂ heterosis average declined 18.6%,F₃ heterosis average declined 20.2%.The size of the five F₂ hybrids mid-parent heterosis recession was:LMY15＞ZMS 48＞XZM2＞ZMS29＞ZMS 46.Among them,F₂ mid-parent heterosis and over-parent heterosis of ZMS 46,LMY 15 and XZM2 was obvious,they had a certain prospect of F₂ heterosis utilization.4.The correlation analysis of plant height,fruiting branch number and boll number from F₂ population of the five hybrids showed that the boll number had significantly positive correlation with plant height and fruiting branch number.It showed that you can help choose some yield traits in breeding selection by selecting the architecture traits.5.A total of 3536 SSR primers were used to screen polymorphism between the five hybrids parents,which resulted in 62,78,86,70,68 polymorphism locus respectively and constructed primary genetic linkage map of LMY15.