Arbuscular mycorrhizae in mango orchards in a Brazilian semi-arid region: influence of phenology, management and plant variety

Abstract

Arbuscular mycorrhizal fungi (AMF) increase the absorption surface of roots, providing greater absorption of water and nutrients from the soil by plants. Thus, it is important to know how arbuscular mycorrhizae are affected by factors such as phenology, management and varieties in mango (Mangifera indica) orchards in the irrigated semi-arid region. With this objective, soil and root samples were collected during the vegetative, flowering and fruiting stages, and in the water stress period before flowering, always on the same trees. The study was carried out in mango orchards of the Keitt and Palmer varieties, in agricultural farms located in Juazeiro - BA and Petrolina - PE, both under conventional management (with fertilizers and paclobutazol). The soil was used to quantify the number of AMF spores and phosphorus content. Mycorrhizal colonization in roots was evaluated in qualitative terms (presence of hyphae, vesicles and arbuscles) and quantitative terms (% of colonization). Total mycorrhizal colonization was high, with averages above 65%, and higher values in the fruiting period. Colonization by vesicles and arbuscles was on average above 45% and 17%, respectively, with higher means also during fruiting. The number of AMF spores in the soil averaged over 130 spores in 50 g of soil, with higher values in the period of water stress. The phosphorus content in the soil did not influence mycorrhizal colonization and the number of spores in the soil. The association of AMF with mango trees was generally affected by management and phenology, regardless of the cultivated varieties.