Selection and Evaluation of Maize Genotypes Tolerant to Low Phosphorus Soil

摘要

Genotype selection for tolerance to low phosphorus (P) stress is an important strategy for the development of maize cultivars growing on soils low in available P. In this study, 15 maize genotypes were selected from 116 inbred lines during a three-year field experiment based on their 100-grain weight at maturity. Some morphological and physiological changes associated with low P stress were investigated at the seedling stage. In order to understand the mechanisms used by genotypes tolerant to low P soil to utilize P from the sparing soluble P forms, five typical maize genotypes selected from the inbred lines, were used in a phosphorus-32 (32P) isotope tracer experiment. The results showed that root growth of the low P tolerant genotypes was accelerated under low P conditions, leading to wider exploration of soil space for the uptake of nutrients. Low P tolerant genotypes had higher P uptake efficiencies and could capture more available soil P under P deficiency than low P sensitive ones. A higher rate of transformation for water-soluble P to slowly available P in P deficient soil than in soil with sufficient P. L-values showed that different cultivars had different soil P use efficiencies and low P tolerance mechanisms. The low P tolerant cultivarDSY-32 regulated soil P use efficiency and plant P content according to the L-value under P fertilizer application, but another low P tolerant cultivar, DSY-2, utilized soil P more efficiently regardless of the L-value.