N₂‐Fixation by roots and rhizosphere of sand dune plants

Abstract

Nitrogenase activity (by acetylene reduction assay) has been found on the roots and in the rhizosphere‐soil of various plant species collected from dune soils (Table 1.) located on the west coast of Denmark. Out of twelve plant species, five plant species (Deschampsia flexuosa, Ammophila arenaria, Calluna vulgaris, Empetrum nigrum and Corynephorus canescens) revealed a positive nitrogenase activity. Among these five, three were temperate grasses. Except Ammophila arenaria, all four plant species were collected from old sand dune and showed nitrogenase activity on roots as well as in their rhizosphere soil, Ammophila arenaria was collected from fresh sand dune and exhibited nitrogenase activity only on roots (Table 2).

Interaction of Rhizosphere Bacteria, Fertilizer, and Vesicular-Arbuscular Mycorrhizal Fungi with Sea Oats

“…have been reported for Ammophila arenaria grown in dune sand with an exogenous carbon (C) source (1). Either low (2,28) or high (R. Ralph, Ph.D. dissertation, University of Delaware, Newark, 1978) rhizosphere nitrogenase activity has been reported for several grasses growing in unamended sand. Significant enhancement of growth, but not of plant-N content, often occurs following root inoculation with asymbiotic N2-fixing bacteria (14,18,22).…”

Nitrogenase (C2H2) Activity in Roots of Non‐Cultivated and Cereal Plants: Influence of Nitrogen Fertilizer on Populations and Activity of Nitrogen‐Fixing Bacteria

“…Highest activities were found with roots of 3 grass species from sandy soil low in COrg. Similarly, Ammophila arenaria, Deschampsia flexuosa and Corynephorus canescens from Danish coastal dunes had a high activity of 260,respectively (Ahmad and Neckelmann, 1978). A consistently high activity as with Tussilago farfara was found also with roots of other Asteraceae (Cichorium intybus, Helianthus annuus, Dahlia veriabilis and Taraxacum officinale) with inuline as storage material (Vlassak and Jain, 1978).…”

“…Nitrogenase activity associated with plant roots was measured by the acetylene reduction technique not only in the tropics, but also with numerous wild plants ( Tjepkema and Evans, 1976,Ahmad and Neckelmann, 1978, Kana and Tjepkema, 1978 and cereals of temperate climates ( P e a h e n et al, 1978). It increases with the rate of photosynthesis, soil moisture and soil temperature, but is diminished with increasing Nmin contents of soils ( Balandreau et al 1978), Dobereiner and De-Polli, 1980).…”

Nitrogen‐fixing Bacteria Associated with Graminaceous Roots with Special Reference to Spirillum lipoferum Beijerinck

“…Using the acetylene reduction test (Dilworth 1966, Hardy et al 1972) significant nitrogenase activities of grass roots were observed after induction by preincubation of washed roots under atmospheres of reduced oxygen tension (Dobereiner et al 1972, Domrnergues et al 1972, Neves et al 1973, Dayet al 1975, Dobereiner and Day 1975, Ahmad and Neckelmann 1978). However, this preincubation for 12 hours with 1-2 % O2 caused a considerably enlarged population of Spirillum lipoferum as a result of the organic acids formed by the roots and other associated microorganisms leading to acetylene reduction rates an order of magnitude higher than with roots left in soil core samples .…”