Characteristics of Phosphorus Nutrition of Different Rice Genotypes under Low-P Stress at Different Growth Stages

The characteristics of phosphorus(P)nutrition in different P-efficiency rice genotypes under low-P stress were studied at different growth stages in a pot experiment.At the tillering stage,except rice line 99112T,low P-tolerant genotype had a higher P uptake rate and utilization efficiency than P-sensitive genotype.At the booting stage,low P-tolerant genotype still had a higher P uptake rate under low P stress,but there were no significant differences in P utilization efficiency between the two genotypes.At the maturity stage,the contribution factors to P efficiency of rice genotypes were in the sequence as follows:utilization efficiency,uptake rate and transportation efficiency.The lesser phosphorus efficiency of rice line 99012S was mainly caused by the lower absorbability of phosphorus at different growth stages.The lower uptake rate and the utilization efficiency of phosphorus at the early growth stage and the lower P utilization efficiency at the later growth stage become the main influencing factors of another low P-sensitive genotype 99056S.Furthermore,the P uptake rate of low P-sensitive genotype was lagged by low phosphorus stress,which could be intensified with the further phosphorus stress.