| dc.description.abstract | Field studies were conducted in 1979 and 1980
at the Field Station, University of Nairobi, to
evaluate dry bean (Phaseolus vulgaris, L) varieties
Canadian Wonder, Mwezi Moja and Rose Coco growth
and yield as influenced by competition from annual
mixed weeds and different weeding .treatments , In
one set of experiments, the beans were left to grow
in weeds the first four and eight weeks respectively
after planting or left to grow with weeds the
entire season. In another set the beans were freed
of weeds the first four and eight weeks respectively
after planting and thereafter kept weed free or
were weeded the entire season. The leaf areas,
dry weights of whole plants, shoots, roots, stems,
leaves as well as plant height and number of
branches per plant were determined at intervals
during the phase of the vegetative growth. At the
end of the growth period, grain yield and yield
components were determined.
Season-long weed competition reduced bean
grain yields by 49.5, 55.5 and 58.0% with ample
moisture in 1980 and by 53.0, 58.0 and 67.0% when
moisture was limiting in 1979 for Canadian Wonder,
Mwezi Moja and Rose Coco respectively.
In all instances, the pod number per plant
was the most severely affected component of yield
and showed similar trend of weed effects to those
observed in grain yields. Seeds per pod and
weight per seed were not affected by weeds except
in cultivar Rose Coco when moisture was limiting
in 1979, when in addition, the number of seeds
per:'pod was significantly reduced by weed
competition.
Plant growth as measured by the total plant
dry weight and the dry weights of other plant
parts named above were significantly reduced by
weed competition lasting eight weeks and beyond
after planting except stems in Mwezi Moja.
Similarly LAI and number of branches per plant were
significantly reduced by weed competition beyond
the reproductive phase (six to eight weeks after
planting).
There was no need to keep the cultivar free
from weeds beyond the fourth week after planting.
However, upto and beyond eight weeks in weeds the
bean growth and yield were significantly reduced. | en |
