last final thesis of umer

yield directly to solar radiation because of factors that influence the relative contributions of
assimilates produced at pre-anthesis and post-anthesis.
According to Evans & Wardlaw (1976), shading and reduced assimilate production will have the
least effect on yield if competition occurs during the vegetative growth phase. Reddy & Willey
(1981) stated that, where the components of an intercrop are in direct competition for light,
increased total biomass production by the crop could result in improved yields.
The capturing of radiant energy drives crop evapotranspiration, and the pattern of its interception
determines the ratio of water use through crop transpiration to that lost in soil evaporation.
Probably the single most disadvantage is that cowpea plants are shaded by the cereal throughout
the growing season, which results in severe reduction in shoot and root growth and ultimately in
low grain and fodder yields. Although cowpeas occupy 50% of the land area under intercropping,
its grain and fodder yields are 10- 20% less than those in sole cropping (Singh et al., 1997; Terao
et al., 1997).
2.13. Intercropping and Weed Effects
It is commonly known that intercropping reduces weed infestation and is one of the integrated
weed management strategies with less effect on the environment than the use of chemical
herbicides. The success of intercropping on weed control is much more diverse when different
legumes are inter-planted and both the cereal and the legume are considered as main crops. The
legume crop under intercropping suppresses weeds through competition for resources (Fortin et
al., 1996).
Weed infestation causes severe yield reductions in field crops, and losses of 40-60% have been
reported under sole maize cropping (Ayeni et al., 1984) although growing crops in a mixture
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