Showing papers on "Sesbania rostrata published in 2016"

A Chemotaxis Receptor Modulates Nodulation during the Azorhizobium caulinodans-Sesbania rostrata Symbiosis.

Abstract: Azorhizobium caulinodans ORS571 is a free-living nitrogen-fixing bacterium which can induce nitrogen-fixing nodules both on the root and the stem of its legume host Sesbania rostrata. This bacterium, which is an obligate aerobe that moves by means of a polar flagellum, possesses a single chemotaxis signal transduction pathway. The objective of this work was to examine the role that chemotaxis and aerotaxis play in the lifestyle of the bacterium in free-living and symbiotic conditions. In bacterial chemotaxis, chemoreceptors sense environmental changes and transmit this information to the chemotactic machinery to guide motile bacteria to preferred niches. Here, we characterized a chemoreceptor of A. caulinodans containing an N-terminal PAS domain, named IcpB. IcpB is a soluble heme-binding protein that localized at the cell poles. An icpB mutant strain was impaired in sensing oxygen gradients and in chemotaxis response to organic acids. Compared to the wild-type strain, the icpB mutant strain was also affected in the production of extracellular polysaccharides and impaired in flocculation. When inoculated alone, the icpB mutant induced nodules on S. rostrata, but the nodules formed were smaller and had reduced N-2-fixing activity. The icpB mutant failed to nodulate its host when inoculated competitively with the wild-type strain. Together, the results identify chemotaxis and sensing of oxygen by IcpB as key regulators of the A. caulinodans-S. rostrata symbiosis.

Characterization of Natural Fiber Extracted from Sesbania rostrata: An Alternative Potential for Synthetic Fibers

Abstract: Enriching natural materials is essential for developing eco-friendly composites in structural and automotive applications. The aim of this work is to extensively characterize new natural cellulosic fiber extracted from Sesbania rostrata stem.      S. rostrata fibers (SRFs) show cellulose content of 64.36 % with a range of tensile strength from 156 to 460 MPa and have a low density of 1.365 g/cm3. SRFs has crystallinity index of 58.41%, which is comparable with that of other common natural fibers. Furthermore, SRFs can resist the degradation of cellulose up to 246°C, which is revealed by thermogravimetric analysis.Â

Sesbania rostrata (Bremek and Oberm.) as biological nitrogen fixator for sustainable lowland rice production

Abstract: Nitrogen plays a crucial role in rice cultivation. It is usually supplied as chemical fertilizer (urea). However, rice monocropping without fallow and loss of urea-N through leaching, often lead to soil fertility decrease, decline in soil organic matter and environmental pollution, which negatively affect rice yield. Climate change is expected to worsen this situation. All this may affect food security especially against the backdrop of increasing population levels, particularly in Sub-Sahara Africa. New and alternative N resources should be explored to sustainably supply rice crop needs and thus reduce the adverse environmental effects of current urea-N use in rice. Biological Nitrogen Fixation (BNF) by legumes is a promising and environment-friendly mechanism that can be used to convert atmospheric di-nitrogen into fertilizers for agriculture. As such, BNF could increase the sustainability of traditional rice production systems. In this respect, Sesbania rostrata, which is native to Africa and frequently used as a green manure in lowland rice production systems, is one of the best N-fixating plant species because its N-fixing bacteria nodulate on both stem and roots, whereas the plant itself grows fast, has high N-fixation rates and tolerates waterlogged soils. The plant, when plowed under at 34-42 days after sowing, can add 90 to 150 kg N ha−1 and 7.4 t ha−1 of biomass to the soil. It has been found that S. rostrata, supplied as a green manure, can double rice yields after one rice cultivation cycle. Findings further reveal a 35% residual effect on yield of the same green manure application on grain yield in a second rice cultivation cycle. It is probably the cheapest alternative N source to smallholder farmers.

Use of organic amendment for management of fusarium wilt of gladiolus

Abstract: The experiment was conducted at Horticulture Research Centre (HRC), Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur during 2009-2011 following RCB design with four replications. Eight soil amendments such as Poultry refuse (5 t ha -1 ), Mustard oil cake (600 kg ha -1 ), Sesbania rostrata (5 t ha -1 ), Municipal waste compost (5t ha -1 ), BARI Trico- compost (2t ha -1 ), Leachate (200 ml m -2 ) were evaluated against Fusarium wilt of gladiolus caused by Fusarium oxysporum f. sp. g ladioli under field condition. Poultry refuse was very effective in inhibiting the disease resulting maximum germination (99.98%), spike length (73.90 cm), rachis length (43.70 cm), florets spike -1 (12.63), flower sticks plot -1 (38.75) and corm plot -1 (60.23) and cormel yield ha -1 (2.51 t). Mustard oil cake, BARI Trico-compost and Sesbania rostrata compost were also effective in inhibiting the disease and resulting better spike length, rachis length, florets spike -1 , flower sticks plot-1 and corm plot -1 and cormel yield. Bangladesh J. Agril. Res. 41(4): 675-684, December 2016