Screening maize inbred lines for tolerance to low-P stress condition

Genotype screening and selection for tolerance to low-phosphorus stress conditions is an important strategy for the development of cultivars growing on soils low in available P. This study was conducted to adjust an existing screening methodology which provides stable, diffusion-limited low-P concentrations for use with maize, and then use the modified methodology to select maize inbreds tolerant to low-P stress during the vegetative stage of development. Low and high-P concentration levels were established that provided a reproducible and diffusion-controlled availability of P to the plants at concentrations of 8-10 µM and 40-50 µM, respectively, of culture medium solution P at the time of transplanting. The procedure was also effective in providing low concentrations of P during the period of plant growth. The sand-alumina culture medium was used to screen 20 maize inbreds known to be efficient in P uptake or accumulation and/or tolerant to aluminum toxicity. The inbreds B37, Oh40B, NY821, Pa36, and MS1334 were selected as tolerant to low-P and WH, H99, H84, Pa32, and W37A were selected as intolerant to low-P in sand-alumina medium.