Single and multi-strain rhizobial inoculation of African acacias in nursery conditions

• Published in: Soil biology & biochemistry Vol. 32; no. 3; pp. 323 - 333
• Main Authors: Sutherland, J.M., Odee, D.W., Muluvi, G.M., McInroy, S.G., Patel, A.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-03-2000; New York, NY Elsevier Science
• Subjects: Acacia; African Acacia species; Agronomy. Soil science and plant productions; Artificial regeneration. Forest nurseries. Planting; Biological and medical sciences; Economic plant physiology; Forestry; Fundamental and applied biological sciences. Psychology; Kenya; Multi-strain inoculation; Natural abundance 15N; Nitrogen fixation; Nursery conditions; Sowing and planting; Symbiosis (nodules, symbiotic nitrogen fixation, mycorrhiza...); Tropical rhizobia; Kenya; East Africa; Africa; African Acacia species; Nitrogen fixation; Natural abundance 15N; Nursery conditions; Tropical rhizobia; Multi-strain inoculation; Symbionte; Tropical zone; Interspecific comparison; Plant juvenile growth stage; Vegetal microorganism relation; Nodulation; Nursery (plant); Isotopic composition; Rhizobium; Multipurpose tree; Nitrogen Isotopes; Soils; Biological fixation; Inoculation; Leguminosae; Dicotyledones; Bacterial inoculation; Seed; Angiospermae; Acacia; Bacteria; Spermatophyta; Rhizobiaceae
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/S0038-0717(99)00157-1

Inoculation experiments were conducted in Kenya on seven African
Acacia species/subspecies (
Faidherbia albida,
Acacia karroo,
A. arenaria,
A. nilotica ssp.
kraussiana,
A. tortilis ssp.
spirocarpa,
A. tortilis ssp.
heteracantha,
A. senegal) in sterilised and untreated soil. The untreated soil contained 10
3 rhizobia g
−1. In six of seven species in untreated soil the multi-strain inoculated plants contained significantly more total nitrogen than control plants. The exception was
A. arenaria in which significant increase in total nitrogen was achieved only with the single strain inoculum in sterile soil. In
A. tortilis ssp.
spirocarpa the single strain was better than the multi-strain inoculum. Significant increases over controls in dry weight ranged from 19 to 75% and in total nitrogen from 11 to 89%. Nitrogen derived from fixation (Ndff) was determined for three species/subspecies using the natural abundance
15N method. Values for fixation for the best treatments in these species were
A. nilotica 53%,
A. tortilis ssp.
heteracantha 45% and
A. tortilis ssp.
spirocarpa 44%. These are conservative values because of the relatively small δ
15N values (−2.85‰ for
A. nilotica and −2.52‰ for both species of
A. tortilis) determined as the 100% fixation values. We conclude that: inoculation can result in substantial gains in nitrogen fixation in African acacias; multi-strain inoculation is preferable to single strain inoculation in some circumstances;
A. nilotica and
A. tortilis have at least moderate nitrogen fixation potential and the wide genetic variation found suggests that substantial improvement may be obtained by selection for this character.