Effect of CO2 enrichment on hormone content of different types fall dormancy alfalfa

To investigate the effects of elevated CO2 on endogenous hormone content of three different fall dormancy alfalfa(Medicago sativa) cultivarsfor the entire growth period of alfalfa processing under three different CO2 concentration gradient (700 μmol·mol-1, 550 μmol·mol-1 and normal atmospheric CO2 concentration 350 μmol·mol-1). The results of measured in each growth stage leaves endogenous hormone showed that: the higher CO2 concentration, the higher auxin (IAA), gibberellin (GA3), the lower content of abscisic acid (ABA) contentin .The IAA/ABA and GA3/ABA of the alfalfa increased by high CO2 concentration handling throughout whole growth period, also, high CO2 concentrations was conducive to the lifting of dormancy alfalfa, maintaining growth. Meanwhile, high CO2 concentrations had a significant effect (P<0.05) of endogenous hormones alfalfa when early flowering and flowering. It was most favorable for growth and development of semi Alfalfa, then the non-fall dormancy alfalfa when the air CO2 concentration increased. The fall dormancy of fall dormancy Alfalfa decreased and the growth period was prolonged in the treatment of high CO2 concentration.