Large-scale screening maize germplasm for low-phosphorus tolerance using multiple selection criteria.

Phosphorus (P) deficiency is one of the major limiting factors in maize production in many developing countries. This experiment was conducted to evaluate multiple low-P tolerance criteria and identify the suitable maize germplasm for our future low-P tolerance breeding. A total of 456 diverse maize inbreds were evaluated for low-P tolerance at seedling stage using four shoot-related traits and six root-related traits measured under applied phosphorus (AP) and non-applied phosphorus (NAP) conditions. Analysis of variance revealed significant genetic variation among genotypes for all tested traits. Medium-to-high heritability estimates were obtained for most traits. Total dry weight (DW) was highly inheritable while the widely used root/shoot ratio had only an intermediate level of heritability. Based on the synthetic index (SI), the tested inbreds were classified into three groups representing low, moderate and high tolerance to low-P stress. Regression model built based on selection criteria for low-P tolerance explained 67.8 and 76.8 % of variation for DW under NAP and AP conditions, respectively. Using low-P tolerance index for DW and SI as selection criteria, 23 and 109 maize inbreds were identified as germplasm resources that were extremely tolerant and sensitive to low-P stress, respectively, which could be further used for genetic improvement of low-P tolerance. [ABSTRACT FROM AUTHOR]