Abstract
Plants have adopted a wide range of morphological and physiological mechanisms to cope with P deficiency in
soil. Crop species and even cultivars within the species differ genetically in these mechanisms and hence in their
response to P deficiency stress. We evaluated growth response and P utilization efficiency of twenty rice cultivars
grown in hydroponics with adequate (260 ~M P) as well as deficient (26 ~M P) levels of P. The cultivars differed
significantly (p<0.001) in biomass accumulation at both P levels. Phosphorus contents varied significantly
(P<0.01) among rice cultivars at both levels of P supply. Positive correlation (p-, 0.01) of shoot dry matter
production in rice cultivars with root biomass (r = 0.70, n=160), P uptake (r = 0.82, n=160) and utilization rate (r =
0.46, n=160) indicated that these are the main morphological and physiological parameters for maximizing shoot
production in P-starved condition. Greater efficiency in dry matter production per unit amount of P absorbed was
obvious in IR 24-PK, 77-74-5-2 and PK 3362-2-1, whereas 33897-11, PK 1818-4-1-7 were least efficient in terms
of specific utilization rate of P.
Keywords: Genetic variability, P use efficiency, P utilization rate, rice
