Allelopathic effect of Pinus tabuliformis root in loess hilly area

This research aimed to provide a scientific basis for the construction of compound arbor-shrub-herb vegetation in Pinus tabuliformis forest by studying the allelopathic effect of P. tabuliformis root on varied plant species. The allelopathic effects of P. tabuliformis root aqueous extract (RAE) on the germination and growth of seven plants (P. tabuliformis, Robinia pseudoacacia, Platycladus orientalis, Lespedeza bicolor, Spiraea salicifolia, Agropyron cristatum, and Medicago sativa) were investigated with different concentrations of P. tabuliformis RAE, i.e., 0.5, 1.0, 3.0, 5.0, 7.0, and 10.0 mg/mL. The results showed that P. tabuliformis RAE inhibited the growth of R. pseudoacacia, A. cristatum, and M. sativa, and such effect increased with the increase of RAE concentration. P. tabuliformis RAE promoted only the growth of P. orientalis at each concentration. At low concentrations, the P. tabuliformis RAE promoted the growth of P. tabuliformis, L. bicolor and S. salicifolia, while it inhibited at high concentrations; at 1 mg/mL the promoting effects changed into inhibiting. We suggest that when constructing compound arbor-shrub-herb vegetation in P. tabuliformis forest, we should give priority to P.orientalis, and carefully choose R. pseudoacacia, A. cristatum, and M. sativa. When choosing L. bicolor and S. salicifolia, we should control the thinning and intercropping density of P. tabuliformis forest.