Endophytic fungus Serendipita indica increased nutrition absorption and biomass accumulation in Cunninghamia lanceolata seedlings under low phosphate

Cunninghamia lanceolata is important forest tree species in southern China, and its successive plantations resulted in degradation of soil fertility in pure stands, causing decline in forest productivity. How to improve productivity in C. lanceolata pure stands is a tough task. Usage of mycorrhizal fungi might be a plausible access to the task. The objective is to study the possibility of the endophytic fungus Serendipita indica (named formerly as Piriformospora indica) in culture of C. lanceolata. Seeds were sowed in plastic pots with river sand. When seedlings had two true leaves, hyphae suspension solution of S. indica was added to near the roots of seedlings in each plastic pot. Such pots with seedlings were placed in a greenhouse and normal management was carried out for the seedlings. Symbiosis effects on root development, nutrition uptake and allocation, and biomass accumulation of C. lanceolata seedlings under low phosphate were investigated. The results showed that S. indica could symbiose with C. lanceolata. The symbiosis did not result in significant changes in root system architecture under low phosphate, but significantly increased nitrogen and phosphorus levels in leaves under low phosphate. Although the symbiosis did not significantly increased nitrogen allocation in leaves under low phosphate, it significantly increased phosphorus allocation in leaves. The interaction between S. indica and C. lanceolata resulted in increase in total biomass under low phosphate and changes in biomass allocation between shoots and roots. The results suggested that S. indica helps host plants to absorb more nutrients under low phosphate and to allocate more nitrogen and phosphate to leaves, promoting plant growth; the fungus might be used in pure stands of C. lanceolata because of its large-scaled axenic culture.