Abstract: Crosses were made by NCII design,using four elite commercial cotton culrivars as female parent and nine transgenic cotton homozygous lines as male parent,to analyze the competitive heterosis and combining ability effect for 36 characters.The results showed that the heterosis for yield and yield traits were obvious in most crosses,yet the seed index had negative heterosis in mostF₁hybrids.For example,the heterosis of lint cotton of 86.1%F₁hybrids and seed cotton of 80.6% crosses were positive,their average heterosis were 17.2% and 7.9%,respectively.There were positive heterosis in lint percentage,boll weight and bolls per plant in mostF₁hybrids.Average hetersises were 4.1%,2.1% and 0.7%,respectively.The results of variation analysis of combining ability showed that there are significant difference for general combining ability among nine teansgenic cotton lines.In four female,The general combining ability of two transgenic cotton cultivars prior to the two non-transgenic female parent.SixF₁hybrids taking on elite special combining ability were selected,nine transgenic homozygous lines were derived from the same acceptor Jihe321,the difference of genetic background was excluded,therefore,the difference of their combining ability were come from the foreign genes expression,inserting sites and somatic cell variance.

Key words: Gossypium hirsutum L, Two types of insec-tresistant genes, Heterosis, Yield traits, Combining ability

CLC Number: 

• S562