Changes in seedling photosynthetic physiology characteristics of Musa varieties under drought stress.

Changes in photosynthetic physiological indices including chromatic value,content of chlorophyll,net photosynthetic rate(Pn),transpiration rate(Tr),stomatal conductance(Gs) and intercellular CO2 concentration(Ci) of three Musa variety seedling leaves under different drought stress conditions were determined.The results showed that the L value,a value and b value of the three species measured 1d after the drought stress at three stress levels declined in comparison with the control.Compared to the control,the chlorophyll content of 'Brazil' and 'Diwangjiao' under light and moderate stress dropped by 14.9% and 30.4%,29.7% and 45.3% separately,while it increased by 12.8% and 2.3% individually under severe drought stress.The chlorophyll content of 'Fenjiao' was significantly lower than that of the control under three stress levels.There was no simple linear relationship between the leaf color value and chlorophyll content for the three varieties.The Pn,Tr,Gs values of the three varieties significantly declined along with the development of drought stress,while the decrement of Pn value of 'Brazil' was the largest,which decreased by 80.1%,83.4% and 92.4% under the three drought levels.The Ci value of the three varieties was all significantly higher than the control.The results showed that the drought resistance of the three varieties was ordered as 'Fenjiao''Diwangjiao''Brazil'.