Research Article SPECIAL ISSUE: Physiology and Ecology of Halophytes—Plants Living in Salt-Rich Environments Growth and nitrogen fixation of legumes at increased salinity under field conditions: implications for the use of green manures in saline environments
Bas Bruning1*, Richard van Logtestijn1, Rob Broekman1, Arjen de Vos2,3, Andre´s Parra Gonza´lez2 and Jelte Rozema1
1 Systems Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam, Amsterdam, The Netherlands
2 Salt Farm Texel, Den Burg, The Netherlands
3 Department of Biological Oceanography, Royal Netherlands Institute for Sea Research (NIOZ), Den Burg, The Netherlands
The use of legumes as green manure can potentially increase crop productivity in saline environments and thus contribute to the sustainability of agricultural systems. Here, we present results from a field experiment conducted in the Netherlands that addressed the efficiency of nitrogen (N) fixation by a legume at varying salinities. We grew Melilotus officinalis in an agricultural field using drip irrigation with water salinity varying in electrical conductivity between 1.7 and 20 dS m21 . In the experiment, nearly 100 % of total plant N in M. officinalis was derived from symbiotic fixation at all but the highest salinity level (20 dS m21 ). Our results indicated that this species derived substantial amounts of N via symbiotic fixation, the N becoming available in the soil (and thus available to crops) when cultivated legumes senesce and decompose. Based on the growth performance of M. officinalis and its ability to fix N at moderate soil salinity in our field experiments, we identified this species as a promising source for green manure in saline agriculture in temperate regions.
Keywords: Halophytes, Melilotus officinalis, salinity, Sesbania, symbiotic nitrogen fixation