© CSIRO 2004 10.1071/EA03012 0816-1089/04/010065 Australian Journal of Experimental Agriculture, 2004, 44, 65–74 CSIRO PUBLISHING www.publish.csiro.au/journals/ajea Effect of Klebsiella pneumoniae and Azospirillum halopraeferens on the growth and development of two Salicornia bigelovii genotypes E. O. Rueda-Puente A , T. Castellanos A,C , E. Troyo-Diéguez A and J. L. Díaz de León-Alvarez B A Department of Environmental Microbiology, Centro de Investigaciones Biológicas del Noroeste (CIBNOR), AP 128, La Paz, Baja California Sur 23000, México. B Universidad Autónoma de Baja California Sur. AP 128, La Paz, Baja California Sur 23080, México. C Author for correspondence; e-mail: tcastell@cibnor.mx Abstract. Growth and development of 2 pickleweed (Salicornia bigelovii Torr.) genotypes, a local wild type and cultivar, SOS-10, were studied under field conditions. When inoculated with the previously selected and cultivated native strains of Klebsiella pneumoniae and Azospirillum halopraeferens, the 2 pickleweed genotypes exhibited increases in some of the growth and development parameters measured, such as weight, plant length and biochemical characteristics, including total protein, ash and total lipid content in selected plant parts. Our findings suggest that yields of both genotypes of S. bigelovii, under field conditions, can be enhanced by the application of K. pneumoniae or A. halopraeferens strains. The potential usefulness of S. bigelovii for agricultural producers in coastal semi-arid zones has been shown elsewhere; our findings suggest that the establishment and growth of this halophyte can be experimentally improved using beneficial bacteria as auxiliary biofertilisers. Introduction Baja California Sur, one of the most arid states of Mexico with 80-mm average annual precipitation, lacks surface water resources. Agricultural activities are, therefore, dependent on wells. Unfortunately, water extraction in excess of the rate of replenishment and the inappropriate use of fertilisers have promoted salinisation of agriculture soil, which is now a major problem in the production of traditional crops (SAGAR 1981). Production alternatives include development of salt-tolerant crops, and selection and evaluation of salt-tolerant plants that already inhibit salt flat areas, focusing on those that might make desirable crops (Ungar 2000). Salicornia bigelovii Torr. (Chenopodiaceae) is a facultative halophyte inhabiting salt flats of the Pacific coast and coastal sandy-soil sustained environments, such as the Gulf of California, from tropical Central America to southern California (Ungar 1987a, 1987b). Saltbush (Atriplex semibaccata), another member of the Chenopodiaceae Family, is a halophyte plant growing readily on the east coast of Australia. Among other halophytes, the species of Salicornia: S. brachiata, S. fructicosa and S. herbacea, are included in the list of potential new crops (over 4200 new crops listed) for Australia (Fletcher 1997), where there is an increasing interest in the remediation effects of saltbush on a range of salt levels in soils (Stove 1997). Salicornia bigelovii is a leafless, annual halophyte with green, jointed and succulent stems that form terminal fruit bearing spikes, in which seeds are borne (Glenn et al. 1994; Gallawa 1996). This plant was identified from many halophyte species tested for possible domestication because of its potential as a new oilseed resource (Glenn et al. 1991, 1995). Several studies on the nutritional conditions necessary to foster growth of S. bigelovii have identified its need for extremely high quantities of nitrogen (N) fertiliser (Mota 1996). Its long-term cultivation would probably produce some pollution (Loveland and Ungar 1983; Gallawa 1996). One way to avoid such harm is to inoculate crop plants with N 2 -fixing bacteria as fertiliser. The application of bacteria able to promote the growth of plants in soil severely affected by salinity has been growing in importance during the last decade (Abaidoo et al. 1990; Arsac et al. 1990; Hamdi 1999). Of bacteria able to promote growth and development, one of the most studied is Azospirillum spp., which has proven effective for several crops (Bashan and Holguin 1997). In this study, data on the effects of 2 N 2 -fixing bacteria on the rhizospheres of 2 S. bigelovii genotypes is evaluated. The first bacteria Azospirillum halopraeferens is salt tolerant (Reinhold et al. 1987). The second bacteria Klebsiella pneumoniae is endemic to S. bigelovii (Rueda et al. 2001) and has N 2 -fixing properties (Chelius and Triplett 2000). This study measured how these bacteria affect the growth and development of the S. bigelovii genotypes, focusing on height, biomass, yield and biochemical parameters (proteins, lipids and fatty acids) of the oil seed. Materials and methods Location and plant material The study was conducted at Centro de Investigaciones Biológicas del Noroeste (CIBNOR), located in Baja California Sur, Mexico, 17 km west of La Paz. We studied 2 genotypes of S. bigelovii, cv. SOS-10 and