Seed inoculation with effective root-nodule bacteria enhances revegetation success
Peter H. Thrall, CSIRO Plant Industry, Centre for Plant Biodiversity Research, GPO Box 1600, Canberra, ACT 2601, Australia (fax + 61 262465249; e-mail Peter.Thrall@csiro.au).
- 1Extensive clearing of native vegetation in Australia has contributed to major environmental problems, including land degradation, dryland salinity, soil erosion and loss of biodiversity. Re-establishing cover with deep-rooted perennial species is a major focus for conservation and sustainable land management, particularly with regard to hydrological control of recharge and saline discharge areas. However, considerable expense is involved in large-scale revegetation programmes and cost effectiveness is a real concern.
- 2Low-cost revegetation approaches are needed that require little maintenance yet can substantially enhance reliable establishment and growth of native trees and shrubs. We evaluated results from direct-seeding field trials that examined the benefits of using native Australian Acacia species inoculated with effective strains of nitrogen-fixing root-nodule bacteria to revegetate degraded landscapes.
- 3On average, inoculation led to a 118% increase in establishment of acacia seedlings, indicating that the use of elite strains of native bacteria can substantially reduce seed requirements. This is a major benefit given the expense of collecting sufficient native seed and the impacts of this activity on remnant population viability.
- 4Particularly at sites experiencing harsher climatic conditions, subsequent survival of inoculated seedlings was significantly greater than for uninoculated controls. Moreover, inoculated acacias grew 10–58% faster than uninoculated controls during the critical early phase of establishment, although this varied among species and sites.
- 5Synthesis and applications. Inoculation of Acacia species or other native leguminous shrubs and trees with elite strains of native rhizobia as part of direct-seeding techniques has the potential to increase the scope, rate and success of land restoration world-wide. Re-establishment of important plant–soil interactions in degraded soils can contribute significantly to the development of biodiverse self-regenerating native ecosystems in agricultural landscapes.