Genetic variations in root morphology and phosphorus efficiency of Pinus massoniana under heterogeneous and homogeneous low phosphorus conditions

The vertical distribution of available phosphorus (P) in the soil is usually heterogeneous with soil depth. However, little is known about the P efficiency of conifer species under vertically heterogeneous low-P conditions. The purpose of this study was to investigate the genetic variations in growth traits and P efficiency of Pinus massoniana, under heterogeneous and homogeneous low-P conditions. Pot experiments consisting of low-P (a low P level in all soil layers), layered-P (a high P level in the topsoil and a low P level in the bottom soil), and high-P (high P levels in all soil layers) conditions were designed and conducted. Three-way ANOVA was used to investigate genetic variations in P efficiency and the major growth traits under these three types of P conditions. There were substantial genetic variations in the major growth traits, including tree height, stem diameter and seedling dry weight, under both heterogeneous and homogeneous low-P conditions. The heritability for major growth traits was high under both types of low-P condition. Moreover, there were significant genotype x P interaction effects for growth parameters. Our results indicate that it may be possible to select Masson pine genotypes with high P efficiency and productivity. The significant genotype x environment interactions should be exploited in breeding, and genotypes showing specific adaptations to certain nutrient environments should be bred and used within that environment.