Abstract:
Cassava (Manihot esculenta L. Crantz) is an important economic crop of Thailand. The plant usually grown in soil low fertility that result in low production potential. Arbuscular mycorrhizal fungi (AMF) naturally lives with cassava root and increase nutrients uptake in plant, especially phosphorus. This research aim to study population diversity and correlation of AMF and native bacteria in rhizosphere soil of cassava plant. The soils were collected from cassava KU 50 variety from 0-30 cm deep around plant root using soil tube. The soils were analysis in physical and chemical properties, nutrients in plant, AMF spore abundance and AMF colonization in root. The result showed that soil moisture from 9 fields of study were in low level with 4.39-9.04 % between 0-15 cm deep and 3.23- 9.09 % between 15-30 cm deep. Soil texture was sandy loam in field 1-3 (15.67-17.53 % clay, 10.85-11.97 % silt, 79.73-88.23% sand) and loamy sand in field 4-9 (0.87-3.80 % clay, 9.80- 16.47 % silt, 79.73-88.23 % sand). The study areas are in Sattahip soil series. For soil chemical properties, pH of studied soils were moderate to slightly acid with low organic matter (OM), low total nitrogen (N), low cation exchange capacity (CEC) but high in available phosphorus (P). The extractable potassium (K), calcium (Ca), magnesium (Mg), sodium (Na) and iron (Fe) were low. The available manganese (Mn), copper (Cu) and zinc (Zn) were medium to high. Analysis of nutrient concentration in cassava leaves found that P, Cu, Mg, Fe, Mn, Zn, Cu and boron (B) are at a sufficient level to meet the needs of cassava, without potassium which is low. Nutrient concentration in cassava leaves studied is sufficient for growth. However, the analysis of nutrient in cassava leaf did not show clear direction. The study of AMF found that at 0-15 cm soil deep, spore abundance was between 4.04-8.48 spore/g soil and had positive correlation with clay content but had negative correlation with silt content and Ca. The colonization in root found between 14.15-32.70 % and had positive correlate with clay content and number of spore but had negative correlation with sand content, P, K and Ca. At 15-30 cm soil deep, spore abundance was between 4.36-8.48 spore/g soil. The colonization in root found between 14.46- 28.39 % and had positive correlation with clay content and number of spore, but had negative correlation with sand content, pH and P. The spores were identification based on morphology and found two main genus which were Glomus and Acaulospora. Fungi sequence studies showed that the highest Actinobacteria followed by Proteobacteria and Firmicutes. Number of spore and colonization had positive correlation with Acidobacteria, Chloroflexi and Ascomycota, but had negative correlation with Zygomycota and Glomeromycota, Acidobacteria Chloroflexi and Ascomycota had positive correlation with Unclassified. Acaulospora and Gigaspora had positive correlate with Neocallimastigomycota, but had negative correlation with Glomus, Glomus had positive correlate with Unclassified and Cyanobacteria.