多汁植物

The leaves of Sedum Karntschaticum and Bryophyllum calycinum grown in the short-day condition are smaller in size, markedly greater in thickness, evidently higher in water content and consequently more succulent than those of the plants grown in the natural-day condition, while the leaves grown in the long-day condition are larger, thinner, less in water content and consequently less succulent than those grown in the natural-day condition. In Sedum the short-day condition .retards the flowering and hastens the formation of underground winter buds, whereas the long-day condition hastens the flowering and suppresses the formation. In Bryophyllum the flowering and the formation of under-ground winter buds could not de observed in any day-length condition so far as this experiment was concerned. The dry matter content of pressed ju i c e obtained by its refractive index in the leaves of -short-day plots of Sedum and Bryophyllum, the osmotic pressure and specific electrical conductivity in pressed juice of the leaves of the short-day plot of Bryophyllum are much smaller than those values in the leaves of the natural-day and long-day plots; the above fact reveals that the concentration of dissolved materials in pressed juice of the short-day leaves is lowered relatively in appearance by the greater water content of the leaves. In spite of the fact, in Sedum and Bryophyllum the spesific gravity and hygroscopic capacity of tissue powder, the dry matter content of watery extract of tissue powder and "corrected concentration index" of the pressed juice are much greater in the short-day leaves than the values in the naturalday and long-day leaves! The "corrected concentration index" of pressed juice is the value of the concentration of pressed juice from which the concentration changes caused by the changes in water content of the plant are eliminated ; the formula for the calculation is as follows : the dry matter content of pressed juice obtained from its refractive index x the water content then existing in the plant. From the a b o ve mentioned results it is concluded that the increased succulency of the leaves of Sedum and Bryophyllum in the short-day condition is accompanied by an indication of the increased dry matter content in the leaves, especially by the accumulation of hygroscopic substances in the leaves.