Nodulation of the legume Pterocarpus indicus by diverse strains of rhizobia
Pterocarpus indicus (Leguminosae: Papilionoideae) is one of the commercial tree legume species that dominate South-East Asia and some Pacific regions (Soerianegara & Lemmens 1993). This species has many common names, such as angsana or sena in Malaysia and Singapore, sonokembang in Indonesia and narra in the Philippines (Corner 1988). Pterocarpus indicus grows on a variety of soil types from fertile agricultural soil to rocky soil, along inundated river banks, swamps and lagoons (Allen & Allen 1981, Corner 1988). It has the status of national tree in the Philippines and has been identified by the Forest Research Institute Malaysia (FRIM) as one of the potential ‘millennium tree’ species for forest plantation establishment in Peninsular Malaysia because of its fast growth and other desirable characteristics (Appanah & Wienland 1993, Lok 1996). However, growth data are restricted to early reports from reforestation projects in the Philippines (Sardina 1951, Assidao & Cerna 1960) and individual amenity trees in Singapore (Wong 1982). Pterocarpus indicus is now mostly grown as an ornamental tree and is relatively rare in forests in South-East Asia due to extensive selective logging (Soerianegara & Lemmens 1993). The timber of P. indicus is classified as light hardwood and is used for light to heavy construction, joists, beams and interior finishes. The wood, which is commonly traded as rosewood, has beautiful distinct growth rings and is ranked among the finest for furniture making, high grade cabinet work, carvings, decorative flooring and musical instruments (Appanah & Weinland 1993, Soerianegara & Lemmens 1993).
Legumes, especially tropical woody species, are important for maintaining ecosystem fertility and are used in soil stabilization and revegetation programmes (Langkamp et al. 1979, Dreyfus & Dommergues 1981). Pterocarpus species are reported to nodulate with Rhizobium and Bradyrhizobium in the field but little is known about the specificity, symbiotic relationships and capacity to fix nitrogen in P. indicus (Allen & Allen 1981, Sprent 2001). Inoculation with N2-fixing bacteria is an advantage where soil populations of compatible microsymbionts are low or absent such as may occur for the rehabilitation of disturbed lands (De Faria et al. 1987, Ndiaye & Ganry 1997) and introduction of industrial plantations (Berger 1993, Hogberg & Alexander 1995).
Inoculation of tree legumes with effective strains of rhizobia may be necessar y in commercial forest nurseries to increase N2- fixation capability following out-planting to the field (Chee et al. 1989, Turk & Keyser 1992, Cheng et al. 2002, Perez-Fernandez & Lamont 2003). Since N deficiency is a major fertility constraint in agriculture and forestry in the tropics, there is an urgent need to exploit N2- fixing tree legumes for sustained productivity. The aim of this study therefore was to investigate the ability of Malaysian P. indicus to form nodules with a diverse range of rhizobia and to identify effective strains with potential for application as inocula in the nursery or field.
|Publication Type:||Journal Article|
|Murdoch Affiliation:||School of Biological Sciences and Biotechnology|
|Publisher:||Forest Research Institute Malaysia|
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