Abstract: The purpose of this study was to investigate how high temperature with low humidity stress and low temperature-humidity stress for 48 hours on leaf amino acids content and the relationship between Bt protein content and amino acids content using two Bt cotton cultivars in plant growth chamber，one was conventional ( Sikang 1), other was hybrid( Siza 3). The results showed that combination stress of temperature and humidity stress increased sharply the content of Asp，Glu，Ala and Arg，but decreased the content of Leu and Ile，and had no significantly effect on the content of Ser，Thr and Val． The combination stress of temperature and humidity stress had significantly effect on the leaf Bt protein content in peak boll period． Leaf Bt protein content was decreased under low temperature-humidity stress after 12 hours significantly，while that of high temperature with low humidity stress dropped sharply after 24 hours． Leaf Bt protein content of low temperature-humidity treatment was lower than that of high temperature with low humidity treatment during stress time． The combination stress of temperature and humidity significantly decreased activity of the GPT and GS，but increased protease activity． There existed significantly negative correlation between total content of main amino acids of Bt protein and Bt protein content． These results suggested that the decrease of leaf Bt content under combination stress of temperature and humidity was closely associated with the decrease of Bt protein synthesis ability and the increase of Bt protein decomposition．

Key words: Combination stress of temperature and humidity, Amino acids, Bt protein, Bt cotton

CLC Number: 

• S562.01