Studies on the effects of relative humidity of the atmosphere upon the growth and physiology of rice plant. IV. Influence of humidity on absorption of mineral nutrients of rice plant.

Abstract

The present study examined the influence of atmospheric humidity on the absorption of the mineral nutrients (potassium, calcium, magnesium and manganese) for 28 days after seeding, using rice plants cultivated by water culture. The following results were obtained : 1. The amounts of K and Ca absorbed were greater under the conditions of a high humidity than those under a low one. The amounts of Mg and Mn absorbed, on the other hand, were lower under the condition of high humidity (Fig. 2). 2. The atmospheric humidity had little effect on the content of K in the leaf blade. However, the contents of Ca, Mg and Mn were strongly influenced : the lower the atmospheric humidity, the higher the contents of Ca, Mg and Mn accumulated in the leaf blade (Table 2, Fig. 3). 3. The content of K in the leaf blade was not influenced by the transpiration rate. However, the contents of Ca, Mg and Mn were strongly affected, becoming higher with an increase in the transpiration rate (Fig. 4). Finally, the absorption of K is increased with higher dry matter production under the condition of high humidity. On the other hand, the absorption of Ca, Mg and Mn are increased with higher transpiration under the condition of low humidity.