A study on relationship between leaf epicuticular wax coverage and drought resistance of five alfalfa varieties

Cuticular wax, exposed at the outermost surface of plant organs, plays an important role in interactions of plants and environment， and also plays a critical role in plant drought tolerance by reducing cuticular water loss. In this study, five alfalfa (Medicago sativa) cultivars: Alfaking, Algonquin, Millionaire, WL525 and WL2321 were used as testing materials to analyze the relationship between leaf epicuticular wax coverage and drought resistance, by observing leaf surface wax coverage and determining wax content, chlorophyll extraction rate and proline content. The results showed that among the five alfalfa varieties, the leaf epicuticular wax distribution of Alfaking was more intensive and wax content was higher, while the leaf epicuticular wax distribution of WL525 was sparse and wax content was lower. The chlorophyll extraction rate of Alfaking was relatively slow, however, that of the WL525 was relatively fast. The proline content of Alfaking was the highest, but that of WL525 was minimum. The drought sensitivity of Alfaking was the weakest when they were treated with 20% PEG6000 (the simulated drought treatment). To comprehensively considered, the leaf epicuticular wax coverage of alfalfa has correlation with drought resistance.