Abstract
The varietal differences in the contents of mineral nutrients in leaves under snow cover was examined in relation to the morphological characteristics of shoots in 16 varieties of broad beans. By snow coverage, the necrotized leaf area of the plant was increased and the contents of K, Ca and Mg in the leaves were decreased. The decrease in the mineral nutrient contents and the increase in necrotized leaf area by snow coverage were less in the snow-tolerant varieties than in vulnerable varieties, implying that mineral nutrients do not leach out easily in the tolerant varieties. Therefore, the wax content related to wettability and the number of wounds on the leaf surface which promote leaching out of mineral nutrients were measured. The tolerant varieties did not contain much wax on the leaf surface, but had a smaller number of wounds, which were caused by graupel fall with strong wind before snow covering, than the vulnerable varieties. Furthermore, in tolerant varieties, the plant height, internode and petiole were short, and total leaf area, leaf area touching on ground and intercellular space of the leaves were small. These morphological characteristics showed a close relationship with the number of wounds. These results suggest that the tolerant variety does not leach out a large amount of mineral nutrients under snow through avoidance of wounding, and that the morphological characteristics of broad bean affect snow tolerant.
