Physiological Studies on Fructification of Peanut : 10. Relation between various nutrient treatments in the fruiting zone and organic acid content of fruit.

Abstract

With the plants of runner type (Chiba No. 45 and No. 74), various nutrient treatments were held on acid-washed sand of the fruiting zone throughout the experiment. Flactional analyses of calcium and organic acid were carried out in the pods of each treatment, namely the samples were extracted by 66 % alcohol, 2 % acetic acid and 1 N hydrochloric acid in the case of calcium, and by distilled water and 1 N hydrochloric acid in the case of organic acid. And constituent organic acids were determinated by paper chromatographic methods. 1. Production of unfilled fruit remarkably increased in the plants which received distilled water, minus calcium, plus nitrogen, plus phosphorus, plus potassium and p1us magnesium. In both cases of shell and seed, content of 1 N HCl soluble calcium made a sharp distinction between the above treatments and other nutrient treatments such as complete, minus nitrogen, minus phosphorus, minus potassium, minus magnesium and plus calcium during the peanut development. But in young fruit, the content of calcium by fractional analysis was almost equal irrespective of the treatments of complete, distilled water and minus calcium. 2. The content of free acid (H2O soluble acid) lessened considerably during fruit development in all treatments holding calcium element. This decrease in acid content was due chiefly to the decrease in contents of free citric and malonic acid. However, the content of free acid in all treatments with-holding calcium such as plus potassium, remained nearly unchanged in shell, and increased in abnormal seed during the season. This increase in acid content of the seed was mainly caused by the increase in content of malonic acid. The content of combined acid (HCl soluble acid) increassed parallel with the content of HCl soluble calcium in shell. And this increased amount was due chiefly to the increase in the content of oxalic acid, so that, it can be conjectured that calcium absorbed from fruiting zone combines with oxalic acid in shell during the maturity. In fact, there were not observed the existence of oxalic acid and the increasing amount of HCl soluble calcium in any treatment of calcium deficiency. But the similar relation was not clear among seeds in all treatments.