[Improvement effects of quicklime and calcium magnesium phosphate fertilizer on acidified soil cultivating Codonopsis...

To solve the problem of soil acidification in the cultivation of Codonopsis tangshen, laboratory experiments were carried out to investigate C. tangshen seed germination, seedling growth and soil exchangeable acid, microbial community structure after applying quicklime (QL) and calcium magnesium phosphate fertilizer (CMP). The results showed that QL and CMP treatments significantly improved the survival rate of C. tangshen seedlings from 147.7% to 326.7% and from 270.1% to 311.2%, respectively. The maximum increase rates of the height of C. tangshen seedlings were 516.7% and 546.3%, and that of root length were 798.0% and 679.2% in the treatments of QL and CMP, respectively. 1‰-4‰ QL or CMP treatments increased the relative chlorophyll content, antioxidant enzyme activity and the content of soluble protein of C. tangshen seedlings, decreased the content of malondialdehyde and superoxide anion radical of seedlings, increased soil pH by 0.88-2.02 units and 0.23-1.19 units, and decreased the exchangeable aluminum content in soil by 53.0%-95.3% and 17.6%-81.3%, respectively. Soil bacterial and actinomycetic abundances were significantly higher in 2‰-4‰ QL or CMP treatments than that in the control. Soil fungal abundance was significantly lower in the QL treatment of 2‰ and CMP treatment of 4‰. 1‰-4‰ QL or CMP treatments significantly increased fresh weight of C. tangshen tubers by 40.5%-78.5% and 28.4%-78.8%, respectively. In conclusion, the suitable quantity of QL and CMP for acidified soil (pH=4.12, ρb=1.15 g·cm^-3, tillage layer=15 cm) amendment were 1.73-3.45 t·hm^-2 and 3.45-6.90 t·hm^-2, and QL and CMP amendment could fit the optimum soil pH (5.5-6.5) for the growth of C. tangshen seedlings.