al., 1998) experiments have shown that N2 fixation in soybean is especially sensitive to water deficits and deIncreasing N2 fixation tolerance to drought has been hindered by creases before transpiration or photosynthesis. Furtherthe labor and costs of quantifying N2 fixation using 15N methodologies. The relative abundance of ureides (RAU) in plant tissues has been more, soybean grain yield und...

High nitrogen (N) accumulation in terrestrial ecosystems can shift patterns of nutrient limitation and deficiency beyond N toward other nutrients, most notably phosphorus (P) and base cations (calcium [Ca], magnesium [Mg], and potassium [K]). We examined how naturally high N accumulation from a legacy of symbiotic N fixation shaped P and base cation cycling across a gradient of nine temperate c...

Nitrogen fixation in waterlogged, soil-straw, and sandday-straw mixtures was measured with the C2H2reduction assay, the I5N-tracer technique, and the Kjeldahl method. The reduction of 6 to 15 moles C2H2 corresponded to the fixation of 1 mole N2. The theoretical ratio is 3 moles C2H2 to 1 mole N2. A ratio of 3 moles C2H2 reduced for each mole of N2 fixed was obtained when samples of sandxlay-str...

K,ZNA, T. M., and J . D. TJEPKEMA. 1978. Nitrogen fixation associated withScirprrs trtral.i~.etl.s and other nonnodulated plants in Massachusetts. Can. J . Bot. 56: 26362640. Nitrogen fixation was measured using the acetylene reduction technique in soil cores of 13 nonnodulated. herbaceous plant species growing in mesic and wetland habitats. Six species that grew in a well-drained portion of an...

Decreased N2 fixation in soybean (Glycine max) L. Merr. during water deficits has been associated with increases in ureides and free amino acids in plant tissues, indicating a potential feedback inhibition by these compounds in response to drought. We evaluated concentrations of ureides and amino acids in leaf and nodule tissue and the concurrent change in N2 fixation in response to exogenous u...

Nitrogen fixation associated with sugarcane was monitored ushg acetylene reducti,on tests and bacteriological techniques. Soil cores and trash from cane fields showed acetylene reducing activity. This activity was usually low in association with sandy soils. Where high activity was detected in soil cores it correlat~d with the wet weight of roots in each core. Nitrogen-fixing bacteria resemblin...

For evaluating N(2) fixation of diazotrophic bacteria, nitrogen-poor liquid media supplemented with at least 0.5% sugar and 0.2% agar are widely used for acetylene reduction assays. In such a soft gel medium, however, many N(2)-fixing soil bacteria generally show only trace acetylene reduction activity. Here, we report that use of a N(2) fixation medium solidified with gellan gum instead of aga...

this research was conducted on polluted soil near the lead and zinc factory in zanjan province through which the effects of two organic and three mineral sources were examined on heavy metals fixation in randomized experiment design. experimental treatments includes bagasse and rice husk in three levels: 1.25, 2.5 and 5%, zeolite in three levels: 5%, 10% and 15%, phosphate rock in three rates: ...

Bryophyte establishment represents a positive feedback process that enhances soil development in newly exposed terrain. Further, biological nitrogen (N) fixation by cyanobacteria in association with mosses can be an important supply of N to terrestrial ecosystems, however the role of these associations during post-glacial primary succession is not yet fully understood. Here, we analyzed chronos...