Influence of snow melt water on the content of mineral nutrients in the leaves of broad bean (Vicia faba L.) under snow cover with reference to snow damage

摘要

The content and distribution of potassium (K) and calcium (Ca) in the leaves of broad bean during the snow cover period were investigated to clarify the role of snow meltwater in snow damage. The experiments were carried out under conditions where air temperature was usually above 0deg C and snow had been melting during the snow cover period. The melt water had an average pH of 4.4 and contained Cl-, SO42- and NO3-. The plants were cultivated in open fields or inside tunnels covered with non-woven fabric to decrease the quantity of melting water. Most of the plants in the open field were damaged after 52 days of snow cover, but the plants inside the tunnel were hardly damaged. The K content in the leaves decreased under snow cover in both plots and the decrease in open field plots was greater than that that in the tunnel plots. Ca content decreased only in the open field plots. Observations of leaves after snow melting with an Electron Prove Micro X-ray Analyser showed that the content of K in the necrotic part of the leaf was lower than that in the healthy part. It is concluded that the minerals in leaves were leached out by continuous snow meltwater and that meltwater is one of the factors enhancing snow damage.