Abstract: Under hydroponic culture,the responses of rice (Oryza sativa) genotypes to low Pstress were respectively evaluated by means of relatively-higher Pconcentration in a controlled system with insoluble phosphate source (Ca₃(PO₄)₂) and of relatively-lower concentration with 0.5 mg P/Lin which NaH₂PO₄ was the soluble phosphate. Relative indices such as relative dry weight of tillers (RTW),total relative plant dry weight (RPW),relative number of tillers (RTN),relative dry weight of root (RRW),relative dry weight of shoot (RSW),relative leaf age (RLA) and relative plant height (RPH) were used to screen as the tolerant indices to Pdeficiency,and the correlations among screening criteria per se were analyzed. The results showed that there were significant differences of tolerant indices to Pdeficiency in the test rice genotypes. When the rice cultivars were exposed to low Pstress with the relatively-higher Pconcentration to be screened,the relative tiller dry weight (RTW),relative shoot dry weight (RSW) and total relative plant dry weight (RPW) could be used as the better screening criteria,especially RTWwas considered as a sensitive and reliable screening criterion because its coefficient of variation (CV) and the variable range of data among the test varieties should be large. However,when rice genotypes were grown in the stress condition with relatively-lower Pconcentration,the screening criteria were diffenent,and it suggested that relative shoot dry weight (RSW) or total relative plant dry weight (RPW) was the best single screening criterion.

Key words: Rice (Oryza sativa), Genotype, Low P stress, Screening criteria, global climate change, litter decomposition, seasonal snow-cover, soil N cycling, ecological process