Sự phân bố và hiện diện của nấm rễ nội cộng sinh (Vesicular Arbuscular Mycorrhyza) trong vùng đất trồng bưởi Da xanh tại Bà Rịa, Vũng Tàu

The study was carried out to determine the distribution and presence of versicular-Arbuscular mycorrhiza (VAM) fungi in rhizosphere soil and roots of Da Xanh pummelo in Phu My town, Ba Ria Vung Tau province. The rhizosphere soil and root samples were collected from 6 - 7 years old pummelo of two main soil types, on two soil layers at depths of 0 - 20 cm and 20 - 40 cm, at 2/3 and the edge of canopy. The results showed that the presence of VAM spore density was higher in red basaltic soil (ferralsols) than black soil (luvisols), and common exist on the topsoil layer (0 - 20 cm) as well as the edge of canopy. Glomus and Acaulospora were two most abundant genera in survey areas, and the proportion of mycorrhizal spores ranged from 53.18 ± 2.59% to 58.54 ± 0.46 and from 23.68 ± 2.96% to 29.33 ± 0.64%, respectively. Increasing the soil depth negatively affected on spore density of VAM fungi. The VAM fungi composition aslo changed with soil depth. The percentage of root colonization by VAM fungi ranged from 56.20 ± 3.11% to 62.00 ± 3.37%, and the highest percentage of root colonization by VAM fungi was detected in red basaltic soil