Effect of Arbuscular Mycorrhizal inoculation on Biomass, Nutrient Uptake, Root Infectivity and Soil Colonization of Papaya (Carica papaya L.) Seedlings

The effect of Arbuscular mycorrhiza (AM) fungi on biomass accumulation, nutrient uptake, mycorrhizal root infectivity and soil colonization was determined in Papaya (Carica papaya) seedlings raised under four phosphorus regimes in sand culture and also in 1:1 sand/soil media under sterile and unsterile conditions. Inoculation with AM fungi increased the plant height, leaf number, and stem girth in relation to un-inoculated seedlings grown under equivalent P concentrations. An increase in plant height, leaf number and stem girth also occurred in both inoculated sterile and un-sterile 1:1 sand/soil media in relation to un-inoculated sterile and unsterile media. Arbuscular mycorrhiza also increased the leaf area and the root, leaf and stem fresh and dry weights and also caused an increase in the uptake of phosphorus and potassium in the leaf tissues. It also favoured mycorrhizal infectivity of roots, soil mycorrhizal spore colonization and increased the root absorptive surface area. This study indicates that AM fungi improves the capacity of papaya seedlings to absorb and utilize plant nutrients possibly by increasing the effective root surface area from which available form of nutrients are absorbed and also by increasing access of roots by bridging the depletion zones. As a low cost technology, arbuscular mycorrhizal inoculation is recommended as part of the regular practise into nursery media used for papaya seedling propagation.