Sesbania

About: Sesbania is a research topic. Over the lifetime, 1172 publications have been published within this topic receiving 23947 citations.

Characterization of Azorhizobium caulinodans gen. nov., sp. nov., a stem-nodulating nitrogen-fixing bacterium isolated from Sesbania rostrata

Abstract: Twenty stem- and root-nodulating bacterial strains isolated from stem nodules of Sesbania rostrata were compared by numerical analysis of 221 phenotypic features with nine strains which effectively nodulate only the roots of this plant and with representative strains from the genera Rhizobium and Bradyrhizobium. Representative organisms from the different clusters were investigated further, together with possibly related organisms, by performing comparative gel electrophoresis of whole-cell proteins and by performing deoxyribonucleic acid (DNA)-DNA and DNA-ribosomal ribonucleic acid (rRNA) hybridizations. 3H-labeled rRNA was prepared from Sesbania stem- and root-nodulating bacterial strain ORS 571T (T = type strain); [14C]rRNA from Bradyrhizobium japonicum NZP 5549T was also used. The following conclusions were drawn: (i) the Sesbania root-nodulating bacterial strains are genuine rhizobia; (ii) the Sesbania stem- and root-nodulating strains are quite different from Rhizobium and Bradyrhizobium, and thus they constitute a separate rRNA subbranch on the Rhodopseudomonas palustris rRNA branch in rRNA superfamily IV; and (iii) the closest relative of these organisms is Xanthobacter, but they are phenotypically and genotypically sufficiently different from the latter genus to deserve a separate generic rank. Because the feature of free-living nitrogen fixation is quite discriminative, a new genus, Azorhizobium, is proposed, with one species, Azorhizobium caulinodans. The type strain is strain ORS 571 (= LMG 6465).

Mycorrhizal inoculant alleviates salt stress in Sesbania aegyptiaca and Sesbania grandiflora under field conditions: evidence for reduced sodium and improved magnesium uptake

Abstract: A field experiment was conducted to examine the effect of the arbuscular mycorrhizal fungus Glomus macrocarpum and salinity on growth of Sesbania aegyptiaca and S. grandiflora. In the salt-stressed soil, mycorrhizal root colonisation and sporulation was significantly higher in AM-inoculated than in uninoculated plants. Mycorrhizal seedlings had significantly higher root and shoot dry biomass production than non-mycorrhizal seedlings grown in saline soil. The content of chlorophyll was greater in the leaves of mycorrhiza-inoculated as compared to uninoculated seedlings. The number of nodules was significantly higher in mycorrhizal than non-mycorrhizal plants. Mycorrhizal seedling tissue had significantly increased concentrations of P, N and Mg but lower Na concentration than non-mycorrhizal seedlings. Under salinity stress conditions both Sesbania sp. showed a high degree of dependence on mycorrhizae, increasing with the age of the plants. The reduction in Na uptake together with a concomitant increase in P, N and Mg absorption and high chlorophyll content in mycorrhizal plants may be important salt-alleviating mechanisms for plants growing in saline soil.

Yield and Soil Nutrient Changes in a Long-Term Rice-Wheat Rotation in India

Abstract: Major improvements in the productivity of rice (Oryza sativa L.) and wheat (Triticum aestivum L.) have occurred in South Asia since 1965-1966 when the Green Revolution began. However, after the 1980s, yield stagnated or declined. We analyzed grain yield trends, soil C, N, P, and K status, and P and K balances in a 14-yr rice-wheat experiment conducted at Punjab, India with 11 treatments comprised of various combinations of inorganic and organic sources of nutrients. Recommended levels of N, P, and K were supplemented with N through farmyard manure (FYM), wheat chopped straw (WCS), or sesbania (Sesbania cannabina Linn. & Merrill). Soil parameters were analyzed in archived soil samples collected periodically from 1988 to 1999. Rice yield declines ranged from 0.07 to 0.13 Mg ha -1 yr -1 dependent on treatment. Wheat yields declined by 0.04 Mg ha -1 yr -1 with applications of 75 and 100% N-P-K fertilizer but were maintained over the 14-yr period in the other treatments. Total soil N and available P and K declined in all the treatments except with FYM, in which total N was maintained and available P increased. Total soil C was either maintained or increased with time. Nitrogen and K depletion may have collectively contributed to the yield decline. Stable wheat yields may have been because of continuing variety improvement, resulting in higher harvest index (HI). Results show that current fertilizer recommendations are inadequate for maintaining yields. This cropping system may not be sustainable without increased K input to maintain soil K above sufficiency levels.

Relationships Amongst the Fast-growing Rhizobia of Lablab purpureus, Leucaena leucocephala, Mimosa spp., Acacia farnesiana and Sesbania grandiflora and their Affinities with Other Rhizobial Groups

Abstract: Colony characteristics, growth in litmus milk, precipitation in calcium glycerophosphate medium and utilization of carbon sources of the root-nodule bacteria isolated from the tropical legumes Leucaena, Mimosa, Acacia, Sesbania and Lablab were similar to fast-growing rhizobia of temperate legumes, particularly Rhizobium meliloti. In agglutination tests, isolates from each host shared antigens with one or more of five Rhizobium strains from Leucaena. Infective characteristics of the fast-growing rhizobia were studied in modified Leonard jars and in agar culture. Cross-infections by rhizobia between these plants were common and the association often effective. Lablab was effectively nodulated by its own fast-growing isolate but only formed root swellings, possibly ineffective pseudonodules, with the other isolates. Slow-growing rhizobia which were able to nodulate Macroptilium atropurpureus were unable to form nodules on these legumes except Lablab which was considered more akin to the cowpea group. All fast-growing isolates nodulated, often effectively, Vigna unguiculata and V. unguiculata ssp. sesquipedalis. The isolate from Lablab also effectively nodulated a number of other tropical legumes which have previously only been reported to nodulate with slow-growing nodule bacteria and it also produced ineffective nodulation on Medicago sativa. This is the first record of an effective fast-growing isolate from Lablab.