The effect of soil moisture on seed production, seed characteristics and short-term dynamics of Cenchrus Biflorus (roxb.) in arid rangelands of Western Sudan
Abstract
This study deals with a phenomenon observed to occur in the
arid rangelands of Western Sudan. During a sequence of seasons of
relatively high or above average rainfall, a dominant annual grass
species, namely Cenchrus biflorus (Roxb.), was noticed to decrease
and almost disappear in some areas while other grass species such
as Eragrostis termula (Steud) tend to increase and almost dominate.
It was noticed that this phenomenon occurred even in places where
C. biflorus was growing almost in a pure stand. Considering the
apparently favourable soil moisture conditions prevailing the
dynamics of decrease or disappearance of C. biflorus seemed to be
abnormal.
It has been reported that the dominance of some grass species
and the decrease or disappearance of others during periods of
favourable soil moisture conditions is mainly due to the
competitive ability of the former species.
This study approached the phenomenon from a different point of
view assuming that ~ factor or factors other than just competition
could be involved in this seemingly complex dynamism. The study
focused on the effect of high soil moisture conditions experienced
during a short rainy season on seed production and seed
reproductive characteristics in C. biflorus.
The study, further, investigated the effect of competition
between C. biflorus and E. termula on seed production and seed
reproductive characteristics in C. biflorus under different levels
of soil moisture.
xiv
The study comprised a field experiment in which C. biflorus
was grown under different levels of soil moisture in a pure stand
as well as in combination with E. termula which was used as a
competitor. Data collected included seedling mortality during the
early stages of growth, days before flowering, seed numbers, seed
weight, and seed viability in C. biflorus.
Results obtained showed that C. biflorus seedlings had better
chances to establish under conditions of high soil moisture than
under conditions of low soil moisture. Competition on the other
hand demonstrated significant effect on mortality rate but it could
not eliminate C. biflorus seedlings under any of the soil moisture
conditions used. At the flowering stage results showed that high
soil moisture conditions prolonged the vegetative phase in C.
biflorus resulting in delayed flowering. The study also
demonstrated that under high soil moisture levels C. biflorus
produced larger numbers of seeds but relatively lighter in weight
than those produced under low soil moisture levels. Finally the
viability of seeds produced was tested and the results showed that
seeds of C. biflorus produced under conditions of high but limited
soil moisture were less viable than those produced under conditions
of low soil moisture.
Citation
Eisa, M. D. B(1997). district The effect of soil moisture on seed production, seed characteristics and short-term dynamics of cenchrus biflorus (roxb.) in arid rangelands of Western SudanSponsorhip
University of NairobiPublisher
Department of Range Management, University of Nairobi
Description
Msc Thesis