Biotechnologie, Agronomie, Société et Environnement (Jan 2016)
Effects of arbuscular mycorrhizae on growth and mineral nutrition of greenhouse propagated fruit trees from diverse geographic provenances
Abstract
Description of the subject. Arbuscular mycorrhizal (AM) fungi are known to promote plant growth by enhancing mineral uptake in nutrient deficient soils. These beneficial effects on plant growth may vary considerably between cultivars of a given species and between plant species originating from different locations. Objectives. The present experiment evaluated the response of three Sahelian fruit trees: néré (Parkia biglobosa [Jacq.] G.Don), tamarind (Tamarindus indica L.), and jujube (Ziziphus mauritiana Lam.), originating from five different geographic provenances, to mycorrhizal colonization, evaluate their respective mycorrhizal dependency (MD) and analyze their leaf and stem mineral composition. Method. Trees were cultivated in a nursery on pre-sterilized soil substrate low in available P (2.18 μg·g-1) with or without inoculum of Glomus aggregatum (Schenck & Smith emend. Koske). The experiment was arranged in a factorial design for each fruit tree species separately: 5 provenances x 2 AM treatments (inoculated and non-inoculated [control]) with 10 replicates per treatment. Plants were harvested six months after inoculation and different parameters were measured. Results. Overall, the results showed significant provenance variations in the plant response to mycorrhizal inoculation. Néré mycorrhizal plants, from two seed sources, tamarind and jujube plants from one seed source had significant higher dry weight and shoot height than those from other provenances. Jujube plants from 3 out of the 5 provenances showed significant higher MD. It then appears that seed provenance happened to be determinant even though AM-root colonization levels (80-90%) do not vary much from one provenance to another. In all cases, the fruit trees benefited from AM fungi with increased N, P and K mineral uptake in aerial parts. In particular P uptake was proportional to MD concentration in AM-jujube plants. Conclusions. These results demonstrate the importance of considering seed provenance when performing pre-selection of mycotrophic plant candidates prior to large-scale fruit tree propagation in orchards and agroforestry systems.
