Abstract:

【Objective】 One efficient approach to enhance plant drought tolerance is to decrease water loss during leaf transpiration through stoma regulation, which results in the variation of leaf temperature. The objectives of this study were to detect the relation between leaf temperature variation and biomass accumulation to serve as an evidence for screening the germplasms tolerant to drought at maize seedling stage under moderate drought stress. 【Method】 Eighty- three elite maize inbred lines from China were used to identify the variation of seedling leaf temperature under moderate drought stress. An infrared thermography was employed to measure leaf temperature. Leaf stomatal conductance and transpiration rate were determined by porometer. Plant biomass was measured by electronic balance. 【Result】 Among the measured maize inbred lines at seedling stage under drought stress, relative biomass weight ranged from 0.271 to 0.997 (relative fresh weight), and from 0.338 to 0.969 (relative dry weight), leaf temperature difference varied between -0.1-+0.5 ℃, which reached to significant levels. Under the drought condition, leaf temperature of drought tolerance lines rose significantly, while those of drought sensitive had not obvious variation. Leaf temperature difference between drought stress and well-watered conditions showed a significant positive correlation with relative fresh biomass (0.283*, 0.288**, n=83) and relative dry biomass (0.239*, 0.273**, n=83). Significant correlations of leaf temperature difference with stomatal conductance and transpiration rate were also detected. 【Conclusion】 Transpiration rate was one of the main causes affecting leaf temperature variation and stomatal behaviour served as an important regulation in leaf temperature response to water stress. Under drought stress, leaf temperature difference can reflect the capability of drought tolerance of maize significantly. It was feasible that infrared thermography could be adopted in screening drought-tolerance germplams at maize seedling stage and accelerates the breeding effect for drought-tolerance as an assistant means.

Key words: maize, leaf temperature, drought, infrared thermography