Abstract:

The salt tolerant variation between transgenic and insect-resistant upland cotton cultivar and normal upland cotton cultivar was identified to provide the guidance for breeding of salt tolerant and insect-resistant cotton cultivar. The experiments of sand and soil pot culture with different salinity were conducted with two types of cotton cultivar, Bt+Cpti upland cotton (Gossypium hirsutum L.) cultivar SGK321 and normal upland cotton (Gossypium hirsutum L.) cultivar SY321, to comparatively study their specific values of salt tolerance and dynamic changes of some salt tolerant indexes in physiology and biochemistry at seedling stage. The results showed that, under salt (NaCl) stress, contents of malondialdehyde (MDA) and Na+ in seedling leaves of SGK321 were higher than those of SY321, and contents of free proline, soluble sugar, carotenoid, K+, chlorophyll a, chlorophyll b and chlorophyll a+b, peroxidase (POD) activity, K+/Na+ value, net photosynthetic rate (Pn), and various values of specific salt tolerance at seedling stage were all lower than those of SY321, its comprehensive index of salt tolerance was by 10.3% lower than that of SY321, the difference was significant. Generally, the salt tolerance of SGK321 was obviously lower than that of SY321 at seedling stage. Further analysis indicated, the salt tolerance of transgenic and insect-resistant upland cotton cultivar was obviously lower than that of normal upland cotton cultivar due to exogenetic and insect-resistant gene. It was the effective way of breeding for salt tolerant and insect-resistant cultivar that to select and exploit parent with strong salt tolerance, and pay more attention to salt tolerant selection.