Growth, Phosphorus and Potassium Nutrition of Long- and Short-Age Rice (Oryza sativa L.) Varieties Under Limited Moisture Availability

Abstract

Phosphorous (P) and potassium (K) are two important nutrients, and their availability in soils at native state to rice plants is limited. Moreover, the responses of short and long-age rice varieties to limited soil moisture availability are not kown, and under limited moisture availability the uptake of P and K to rice plants are further restricted. Therefore, a pot experiment was conducted to study the responses of short and long age rice varieties at P, K and moisture limited conditions. Two rice varieties; Bg 379-2 as a long duration (LD), and Bg 250 as a short duration (SD), two water treatments; continious flooding of pots until harvest (W l), and continuous flooding until flowering and then allowing the top soil of a pot to dry out gradually while the subsoil was kept moist through capilary action (W2) were tested with three replicates. Department of Agriculture recommended N, P and K fertilizer levels were applied. At physiological maturity of each variety plant height, productive and unproductive tillers, dry weight (DW) of shoot and roots, tissue P and K concentrations, available and solution P, and exchangable and soltion K concentrations in the soil were measured. Dry weight of both shoot and root were similar between moisture treatments, except for the increased shoot DW of SD at top soil drying condition. Rice varieties were more resonsive to P than K, and LD had adptations such as increase in root DW, solubility of P in the rhizosphere.