[Screening methodology for rice (Oryza sativa) genotypes with high phosphorus use efficiency at their seedling stage].

Under hydroponic culture, the responses of rice (Oryza sativa) genotypes to low P stress were respectively evaluated by means of relatively-higher P concentration in a controlled system with insoluble phosphate source (Ca3 (PO4)2) and of relatively-lower concentration with 0.5 mg P/L in 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 P deficiency, and the correlations among screening criteria per se were analyzed. The results showed that there were significant differences of tolerant indices to P deficiency in the test rice genotypes. When the rice cultivars were exposed to low P stress with the relatively-higher P concentration 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 RTW was 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 P concentration, the screening criteria were different, and it suggested that relative shoot dry weight (RSW) or total relative plant dry weight (RPW) was the best single screening criterion.