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Rice is a globally important food crop, and phosphorus is an essential nutrient element for rice growth. In many of China’s arable lands, there is a deficiency in available phosphorus content. Therefore, screening and breeding rice germplasm resources that are tolerant to low phosphorus can enhance the growth capability of rice in low-phosphorus soils. This study set up treatments with two phosphorus concentrations: H₂PO₄⁻ at 0.18 mmol/L, referred to as normal phosphorus (NP), and H₂PO₄⁻ at 0.009 mmol/L, referred to as low phosphorus (LP). Using hydroponic methods, 156 different genotype rice germplasms were treated for 35 days, after which the morpho-physiological traits of the rice seedling shoots, root morphology, and material content were measured. An analysis of the coefficient of variation (CV) for low phosphorus tolerance coefficients across different rice germplasm resources revealed that 16 indicators had CVs greater than 10%, which can be used as criteria for screening rice varieties with low phosphorus tolerance at the seedling stage. The relevant indicators and low-phosphorus resistance characteristics of different rice varieties were comprehensively evaluated using principal component analysis, correlation analysis, membership function, and cluster analysis methods. The results indicate that the principal component analysis transformed 23 indicators into 5 comprehensive indicators, with a cumulative contribution rate of 86.947%. The D value was evaluated in a comprehensive evaluation of low-phosphorus resistance, and 156 rice germplasm resources were divided into four types by cluster analysis. A scatter plot was created using the comprehensive phosphorus efficiency values of different rice germplasms under normal phosphorus and low phosphorus conditions. Through further verification, the germplasms with strong low-phosphorus tolerance finally selected through comprehensive screening were Y3-14, Y3-35, Y3-21, Jinnongda 705, Changjing 625, and Jinnongda 873. The germplasms with poor low-phosphorus tolerance were Jijing 338, Jingu 981, Tong 35, Y3-31, and Longdao 20. Full article

Phosphorus (P) deficiency is a major factor limiting rice yield throughout the world. Fortunately, some rice accessions are tolerant and can thrive well, even in soils with low P content. The ability to uptake P is heritable, and thus can be incorporated into rice cultivars through standard breeding methods. The objective of this study was to screen for tolerance to phosphorus deficiency and validate the tolerant accessions with phosphorus uptake 1 (Pup1) gene-linked markers in Thai indigenous upland rice germplasm. One hundred sixty-eight rice varieties were screened in a solution culture and assigned a phosphorus deficiency tolerance index and plant symptom score. Eleven upland rice accessions (ULR026, ULR031, ULR124, ULR145, ULR180, ULR183, ULR185, ULR186, ULR213, ULR260, and ULR305), together with the lowland rice cultivar (PLD), were classified as tolerant. They were each validated by nine markers linked to the Pup1 locus and observed for the expected polymerase chain reaction (PCR) product of 0 to 9 markers. The presence or absence of the tolerant allele at the Pup1 locus showed only a slight relationship with the tolerance. Moreover, some lines such as ULR183 and ULR213 expressed high tolerance without the Pup1-linked gene product. Both accessions are useful for the exploration of novel genes conferring tolerance to phosphorus deficiency. Full article