Physiological characteristics of inbred line maize seedling root under phosphorus stress Uptake and Use of Sparingly Soluble Phosphorus by Rice Genotypes with Different P-efficiency Evaluation of Phosphorus Efficiency in Rapeseed (Brassica napus L.) Recombinant Inbred Lines at Seedling Stage Characteristic of growth and development of maize inbreds with different phosphorus efficiency under low-P stress