Influence of the soil conditions on the sprout-growth of tubers and tuberous roots

Abstract

1. The investigations were carried out about the influences of the soil moisture and soil density on the germination of tubers and tuberous root of potato, taro, and Iseimo (one species of Chinese yam), and about the relation of the oxygen and carbon dioxide in the soil atmosphere to the germination of potatoes. 2. With the porous soil the suitable soil moisture for germination of tubers and tuberous roots is 60% of water capacity, but in the case of the dense soil it is 40%. Increasing soil moisture over these optimum levels, the normal respiration of tubers and tuberous roots are more or less disturbed owing to the decrease of the air content and air permeability in the soil. When the air content decreases below 30%, the velocity of the sprout growth of the tubers and tuberous roots declines. 3. A, sufficient quantity of oxygen must be supplied for the germination of tubers and tuberous roots. As to potatoes, under low oxygen supply with in 4-12% of soil atmosphere, the bud and root growth and development do not reach 30% and root weight is only 13_??_14%, of those under sufficient oxygen supply, such as 16_??_18% of soil atmosphere.