Abstract:

Studies reviewed and reported herein showed that
single plant selection can be used to improve simple
characters such as plant height pods per plant and pod
clusters/plant. For the complex characters such as
seed yield and protein content phenotypic recurrent
selection was more effective. Tall, indeterminate plant
types performed best under non-stress water conditions
where secondary growth was not affected. The short
cultivars, however performed well during both seasons
since they escaped the pest population build up at the
end of the seasons. Under water stress conditions high
population levels (upto 110,000 plants/ha.) with more
square arrangements were suitable for tall and short
plant types but under non-stress conditions low populasuitable
for the tall cultivar due to the extra growth.
yield components.
tions (40,000 plants/ha.) with wide spacings were more
Both population and spacing had little or no effect on
Up to 37% natural cross-pollination was recorded in the crop and was mostly carried out by insects. Generally the results observed in F^ regarding the
nature of gene action were in agreement with those of
but various degrees of dominance for various
characters were observed in F2and F2 generations. The
gene action controlling most of the characters was
simple and additive. High heterosis with low inbreeding
depression was observed for most of the crosses
but no reciprdcal differences were noted for any
character. General combining ability variances were
higher than specific combining ability variances in
generations indicating the importance of
additive gene action. The combining ability of some
lines was high indicating that hybrid and composite
varieties can be developed.
Phenotypic correlations indicated that plant widih.
and height, days to maturity, pods and pod clusters/
plant, seeds/pod and seed size
components of this crop. A path-coefficient analysis,
however, showed that pods and pod clusters/plant, seeds/
I
and F^
F2
F1
in the crop and was mostly carried out by insects.
were the main yield
pod and seed size were the main yield components hG'.'f •maximum direct effects on yield. High heritability
estimates (h ) were observed for plant height and width pods/plant, seeds/pod and seed size and low estimates for protein content and seed yield.