Salt Tolerant Variation among Parents of Different Genotype Upland Cotton and Their Hybrids

The experiments of sand and soil culture with different salinity levels were conducted with four cotton strains,Kang 96(male),Bt(Bacillus thuringiensis) transgenic upland cotton(Gossypium hirsutum L.),Lu 58(female),non-transgenic upland cotton,and their hybrids(F1 and F2).The specific values of salt tolerance and some salt tolerant indexes in physiology and biochemistry at the seedling stage were comparatively studied.The results showed that,along with the increase of soil salinity content,K+ content in seedling leaves of each strain decreased,the Na+ content obviously increased,K+/Na+ value reduced significantly,the contents of malondialdehyde,free proline,soluble sugar and carotenoid increased to a certain extent,and net photosynthetic rate of each strain decreased.The peroxidase activity of each strain in 0.23%NaCl treatment was the highest,it took the second place in 0.46%NaCl treatment,and it was the lowest in control among the three treatments.In physiological,biochemical and comprehensive indexes of salt tolerance,Lu 58 was the highest,Kang 96 was the lowest,F1 and F2 were between their parents among the four strains.Further analysis indicated,in salt tolerance,Lu 58 was the strongest,Kang 96 was the weakest,F1 and F2 were between their parents among the four strains,and the salt tolerance of cotton hybrids was confined by their parents.