Analysis of several physiological index characteristics of transgenic Bt cotton cultivars related to damage of Lygus lucorum.

The physiological characteristics of different transgenic Bt cotton cultivars and their correlations with the damage of Lygus lucorum were studied.The results showed that: among the 6 tested cotton cultivars,the occurrence quantity(or damage degree) of Lygus lucorum on hybrid transgenic Bt cotton cultivars was the most(or the most serious),followed by conventional transgenic Bt cotton cultivars and conventional non-transgenic Bt cotton cultivars.The occurrence quantity and damage degree of Lygus lucorum were significantly or very significantly positively correlated with the soluble sugar content in the young buds and shoots,while they were significantly or very significantly negatively correlated with the condensed tannin content and PLA activity.For the soluble sugar content in the young buds and shoots,hybrid transgenic Bt cotton cultivars were the highest,followed by conventional transgenic Bt cotton cultivars,and conventional non-transgenic Bt cotton cultivars were the lowest.For the condensed tannin content and PLA activity in the young buds and shoots,conventional non-transgenic Bt cotton cultivars were the highest,followed by conventional transgenic Bt cotton cultivars,and hybrid transgenic Bt cotton cultivars were the lowest.The accumulation of nitrogen in cotton plants had a significantly or extremely significantly positive correlation with the soluble sugar content in the young buds and shoots,and a significantly or extremely significantly negative correlation with the condensed tannin content and PLA activity.As for the nitrogen accumulation in cotton plants at bud and boll stages,hybrid transgenic Bt cotton cultivars were the highest,followed by conventional transgenic Bt cotton cultivars,and conventional non-transgenic Bt cotton cultivars were the lowest.The above results suggested that the characteristic of high nitrogen accumulation in the plants of transgenic Bt cotton cultivars(especially hybrid transgenic Bt cotton cultivars) led to the characteristics of high soluble sugar content,low condensed tannin content and low PLA activity of young buds and shoots.