基于远红外热成像的叶温变化与玉米苗期耐旱性的研究

Identification of Maize Drought-Tolerance at Seedling Stage Based on Leaf Temperature Using Infrared Thermography

【目的】植物可以通过降低叶片气孔蒸腾来达到控制失水和增强抗旱的目的。蒸腾强度的变化会引起植物叶片温度的变化,利用远红外热成像仪研究遭受干旱胁迫时玉米自交系苗期叶温的变化与生物量耐旱系数间的关系,为筛选鉴定玉米耐旱自交系提供依据。【方法】以83个优良玉米自交系为材料,利用远红外热成像仪检测干旱胁迫条件下苗期叶片温度的变化,叶片的气孔导度、蒸腾强度采用气孔计Li-1600测定,同时测定植株的生物量。【结果】遭受干旱胁迫时,玉米苗期叶片的相对生物量变异幅度为0.271～0.997(生物鲜重)、0.338～0.969(生物干重),叶温变异幅度为-0.1～+0.5℃,均存在显著变异。耐旱玉米自交系的叶片温度显著上升,而敏感玉米自交系的叶片温度变化不明显。干旱胁迫与正常灌水条件下叶温的差值即叶温差与相对生物鲜重(0.283*,0.288**,n=83)及相对生物干重(0.239*,0.273**,n=83)间存在极显著的相关性。此外,叶温差与叶片气孔导度、蒸腾强度间也存在着显著的相关性。【结论】遭受干旱胁迫时,玉米苗期叶片温度变化可以显著反映玉米苗期的耐旱性,叶温差可以作为玉米苗期耐旱性初步筛选的一个指标,将远红外热成像技术运用于玉米耐旱育种存在可行性。

[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] Eightythree 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.