Nitrogen fixation associated with maize plants (zea mays l.) in a temperate and a tropical soil

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Date
1987Author
Mwaura, Francis B.
Type
ThesisLanguage
enMetadata
Show full item recordAbstract
In the temperate soil, low rates of acetylene
reduction activity were detected in excised roots of
field grown maize without preincubation. A higher
acetylene reduction activity (20 nmol C2H4/ g d.wt./
24 h) was recorded under an atmosphere containing 5%
oxygen than when the roots were incubated under 0% and
20% oxygen. Most probable number (MPN) counts of N2-
fixing bacteria associated with field grown maize in
the temperate soil were estimated at 7.0 x 106 cells/ g
d:wt. roots. The acetylene reduction activity
rhizosphere soil was very low (1.7 - 5.8 nmol C2H4/ 10
g d.wt. soil/ 24h) but higner than that recorded in soil
sampled between the-maize., plarlt rows (0.8 - 2.8 nmol
C2H~/ 10 g d.wt. soil/ 24 h). Soil amendment with
glucose stimulated the nitrogenase activity threer
hundred fold or more over a 72 h period. The reduction of
acetylene to ethylene by intact maize plants grown in
the temperate soil was immediate without significant
lag periods. Higher rates of nitrogenase activity were
observed in intact maize plants incubated under aerobic
than under anaerobic conditions.
Citation
Doctor of philosophySponsorhip
University of NairobiPublisher
Department of Botany, College of Biological and Physical Sciences