Mycorrhizal Association and its Benefits to Allanblackia parviflora Tree Seedlings in the Nursery

Allanblackia species are high value multipurpose indigenous fruit trees whose seeds contain edible oil that has become a foreign exchange earner for rural-based enterprises. Wild harvesting could not sustain the supply to industry and therefore domestication was focused on developing propagation techniques, selecting and collecting elite planting materials. Little emphasis was placed on the soil nutrient requirements where preliminary results showed seedlings grown in rhizosphere soil of wild trees had good growth performance. A study was undertaken to examine microbial-Allanblackia parviflora plant interactions and determine their benefits to nursery seedlings. Roots of wildlings and rhizosphere soil from A. parviflora trees were collected from three forest reserves and the roots assessed for mycorrhizal colonization. Allanblackia parviflora seedlings were raised in different potting media with different ratios and their height and diameter determined. Soil treatments were also analyzed for nutrient and chemical contents. Vesicles, arbuscular structures, hyphal coils and intercellular hyphae were found on root tips of wildlings collected from rhizosphere soil of Allanblackia (AB) trees and seedlings grown in soil treatments containing AB soil. Root colonization of A. parviflora was largely in the form of extensive cell-to-cell growth of hyphal coils characteristic of Paris-type morphology. Addition of Agricultural field soil (Ferric Acrisol, Afs) or Humus (H)+Afs to AB improved height of seedlings. Seedlings grown in AB soil alone increased best in height with age followed by those grown in combination of 75% AB soil and 25% Afs. Available P was highest in Afs (220.84 mgP/kg) and low in AB soil (6.54 mgP/kg) while combination of H + Afs to AB increased K level to 341.34 mgK/kg. The improvement in growth must be due to both vesicular-arbuscular mycorrhizal fungi and soil chemical content of AB soil.