Studies on the Effects of Soil Physical Conditions on the Growth and Yield of Crop Plants : VIII. Efects of aeration treatment on the nutrient absorption and tuberous root formation of sweet potato.

Abstract

By managing so that a tuberous root forming place and a nutrient-absorbing place could be distinguished, the authors made these experiments to probe the effects of aeration treatment to each place and the amount of fertilizer (ammonium sulfate and potassium sulfate) on the growth of the top parts and the thickening of tuberous root. The results obtained may by summarized as follows. 1) The authors investigated the effects of aeration treatment in the soil where nutrient-absorbing chiefly took place, the condition of the soil where tuberous root was fomed being equal. As a result, it was observed that the growth of the top parts and the thickening of tuberous root were checked by the poor of the soil aeration and the soil compaction of a nutrient-absorbing place. However, when air was injected and O2 concentration in soil air was increased, the growth of the top parts and the thickening of tuberous root were remarkably promoted. On the other hand, when N gas was injected in that place and O2 concentration in soil air was decreased, the growth of non-tuberous root was promoted and the weight of the top parts increased, although the thickening of tuberous root was hampered and its weight decreased. When the soil of a nutrient-absorbing place was loose and the soil aeration was kept to be excellent, both the growth of the top parts and the thickening of tuberous root were greatly promoted and-the weight of tuberous root could be increased. 2) The authors examined the effects of fertilizer treatment to a tuberous root-forming place and a nutrient-absorbing place on the thickening of tuberous root. As a result, it was found that to apply much nitrogenous fertilizer (ammonium sulfate) promoted the growth of the top parts remarkably but hampered the thickening of tuberous root to some extent. On the other hand, to apply a great deal of potash fertilizer (potassium sulfate) hardly affected the growth of the top parts. but promoted the thickening of tuberous root and increased its weight. 3) The authors examined the effects of soil aeration to tuberous root-forming place on the growth of the top parts and the thickening of tuberous root, the condition of a nutrient-absorbing place being equal (in water culture). When N gas was injected in the soil and of concentration in soil air was decreased, the growth of the top parts was not affected so much, but the thickening of tuberous root was checked and its weight was decreased considerably.