The Mechanism of Phosphorus Uptake from Insoluble Phosphate by Citrus Plant with Mycorrhiza:Ⅰ. Effect of Phosphatase Activity on Phosphorus Uptake of Citrus Seedling with VA Mycorrhiza
Tang Zhengyao (Citrus Research Institute,Chinese Academy of Agrcultural Sciences) Hou Shoulin (Southwest Agricultural University)
A pot experiment was carried out for trifoliate orange(Poncirus trifoliata) seedlings on sterilized red soil, which was amended with an insoluble P fertilizer—rock phosphate (RP) and a soluble P fertilizer—superphosphate (SP) at the same rate (160ppm) of total P, respectively. Three treatments were designed as follows: (1)Seedlings were inoculated with the Vesicular-arbuscular. mycorrhizal fungus (Glomns citricolum)in the soil applied RP; (2)Seedlings were inoculated as above in the soil applied SP; and (3) Seedlings were not inoculated in the soil applied RP as control. After four months, the percentage of myeorrhizal infection of seedlings was 14. 9％ for the RP treatment, increasing 52. 0％ compared with the SP treatment. Mycorrhizal colony could significantly stimulate citrus roots to excrete acid phosphatase in soil. Phosphatase activity. of the RP treatment was 29.8％ up on that of the SP treatment. P content increased with increasing phosphatase activity, indicating mycorrhizal fungi can enhance P uptake from insoluble phosphate by citrus plant.