EVALUATING INTERNAL PHOSPHORUS REQUIREMENT OF RAPESEED, CHICKPEA, LENTIL, AND WHEAT BY SEED ANALYSIS

Foliar tissue in contrast to seed is considered a superior plant part for determining the nutrient-element status of crops and soils. This s tudy tested that generalization for oilseed, legume, and cereal crops. Internal phosphorus (P) requirements were estimated in pot culture ex periments using a P deficient alkaline calcareous soil of Pakistan. Th e order of response (of grain yield) to P fertilization was rapeseed > wheat > lentil > chickpea. Phosphorus concentrations in whole shoots (less-than-or-equal-to 30 cm) associated with 95% grain yields were: w heat and lentil, 0.28%; rapeseed, 0.27%; and chickpea, 0.18%. Critical P concentration in recently matured leaves were: chickpea, 0.39%; len til, 0.33%; wheat, 0.30%; and rapeseed, 0.28%. Mature grains of crops, particularly of rapeseed and chickpea, proved a good indicator tissue for evaluating P status of soils and plants. Phosphorus concentration s in seeds were associated with the P status of soil on which they gre w. Internal P requirement in seeds were: rapeseed, 0.72%; chickpea, 0. 37%; lentil, 0.26%; and wheat, 0.22%.