关键词: 石灰岩土壤, 适生植物, 根际, 磷

Abstract:

Plant utilization of phosphorus in black calcareous soil was studied in Bidens pilosa, Mahonia fortunei and Cupressus funebris. Soil pH value, available phosphorus content, the distribution and transformation of inorganic phosphorus in rhizosphere and non-rhizosphere soils of these three plants were measured. Phosphorus content of plant was also measured and was 3 475, 2 609 and 3 466 mg·kg^-1 in B. pilosa, M. fortunei and C. funebris, respectively. The pH value in rhizosphere soil was significantly lower (P<0.05) than that of non-rhizosphere in B. pilosa (7.35 compared with 7.47), M. fortunei (7.47 compared with 7.67) and C. funebris (7.42 compared with 7.49). Available phosphorus of B. pilosa was accumulated in rhizosphere soil, but those of the other two species in rhizosphere soil were decreased. Compared with the content in non-rhizosphere soil, the contents of Ca₂-P and (Ca₈-P+Fe-P+Al-P) of B. pilosa in rhizosphere soil were increased by 0.89% and 2.13%, respectively, while the content of (Ca₁₀-P+O-P) was decreased by 3.03%, the total content of inorganic phosphorus of B. pilosa in rhizosphere soil was lower than that in non-rhizosphere soil. The content of (Ca₈-P+Fe-P+Al-P) of C. funebris in rhizosphere soil was increased by 0.92%, while the contents of Ca₂-P and (Ca₁₀-P+O-P) were decreased by 0.09% and 0.83%, respectively. The total content of inorganic phosphorus of C. funebris in rhizosphere soil was lower than that in non-rhizosphere soil. The content of Ca₂-P of M. fortunei in rhizosphere soil was unchanged, the content of (Ca₈-P+Fe-P+Al-P) was decreased by 1.29%, and the content of (Ca₁₀-P+O-P) was increased by 1.29%. The total content of inorganic phosphorus of M. fortunei in rhizosphere soil was higher than that in non-rhizosphere soil. The results showed that B. pilosa could decrease the pH value of the rhizosphere soil and activate (Ca₁₀-P+O-P), elevate the level of available phosphorus, effectively absorb and accumulate phosphorus from the soil. Utilization of phosphorus in B. pilosa was therefore stronger than that in the other two plants.

Key words: calcareous soil, adaptive plant, rhizosphere, phosphorus