[Root architecture and phosphorus efficiency of different provenance Pinus massoniana under low phosphorous stress]

Taking four representative provenances of Pinus massoniana from Chun' an of Zhejiang, Wuping of Fujian, Cenxi of Guangxi, and Xinyi of Guangdong in East and South China as test materials, a pot experiment was conducted to study their variations in root architecture and phosphorus (P) efficiency under heterogeneous and homogeneous low P stress. Large variations were detected in the major growth traits and the indices of P efficiency among the P. massoniana provenances under both heterogeneous and homogeneous low P stress. Under heterogeneous low P stress, the provenances from Xinyi of Guangdong and Wuping of Fujian exhibited higher P efficiency and greater dry matter accumulation, and their root architecture presented large adaptive changes, with the values of root parameters in P-rich soil surface layer being significantly higher than those of the P inefficient provenances from Chun'an of Zhejiang and Cenxi of Guangxi, which should be responsible for the higher P absorption efficiency and high P efficiency of the provenances from Xinyi and Wuping under heterogeneous low P condition. The root architecture parameters in P-rich soil surface layer and the plant dry matter accumulation of different provenance P. massoniana under heterogeneous low P stress had a correlation coefficient >0.95. Under homogeneous low P stress, the provenances with higher P efficiency had a significantly higher P uptake efficiency than the provenances with lower P efficiency, but the root parametres of the provenances with higher P efficiency had no significant correlation with the P efficiency of the provenances. There existed differences in the adaptive mechanism for the heterogeneous and homogeneous low P stress among the the P. massoniana provenances, and thus, different strategies should be adopted in the selection of P-efficient provenances for different forest stands.