Effects of External Chemical Regulation on Bt Transgenic Cotton Plants under Combined Stress of High Temperature and Water Deficit

[Objective] The study aimed to find a possible way to combat or alleviate the negative effects caused by high temperature and water deficit at the growth stage of peak boll-setting.[Method] With Bt transgenic cotton GK22 as the test cultivar,a potted experiment was carried out to investigate the effects of the regulation of external substances(the water solutions of pix,urea and their mixture) on the physiological parameters,insecticidal protein content,yield and yield component of cotton plants in artificial climate chambers treated with high temperature and water deficit.[Result] The application of external pix,urea or their mixture was effective in stabilizing the physiological parameters of cotton plants,insecticidal protein content,yield and yield components.Compared with the exclusive application of pix and urea,the mixture of pix and urea played the most effective role in stabilizing the content of chlorophyll,soluble sugar and insecticidal protein,alleviating the increase of the content of free amino acids and proline,and increasing boll number per plant,boll weight and seed cotton yield.[Conclusion] The water solutions of pix,urea or their mixtures can be used to combat or alleviate the stress of high temperature and water deficit if they are sprayed onto cotton plants prior to stress occurrence.