Abstract: This paper deals with the infectivity and effectiveness of VAmycorrhizal fungi in red soils derived from quarternary red clay in hilly areas of central China. Propagule number of indigenous VAMfungi in red soils under natural vegetation, planted with upland crops and suffered from erosion was 33, 50 and 2—3 per 100g soil respectively estimated by MPNmethod. Development of infection was paralleled with the population of VAMfungi in soil. There was a lag phase of infection in cultivated red soil and mycorrhizal infection was quite low throughout the whole growing period on eroded red soils. VAMinfection in both cultivated and eroded soils was promoted significantly by mycorrhizal inoculation. Proper liming and phosphorus fertilization also encouraged VAMinfection of plants on both soils, and hence the total amount of phosphorus and plant growth were greatly enhanced.

Key words: VA mycorrhiza, Propagule number, Infectivity, Development of intection, Mycorrhizal response