Enhancing the competitive ability of crops - Ecological Management of Agricultural Weeds - page 282

Figure 6.5 Effect ofcrop pattern on percentage ofland area occupied by weeds in
the model ofFischer & Miles (1973).Crop density was 300 m 2 ,and curves are
shown for weed densities of50,100,and 200 m 2 .Growth rate and emergence
date were the same for the crop and the weeds.The vertical line shows the degree
ofrectangularity equivalent to a random (Poisson) placement ofthe crop plants
( b / a 3.537).(Drawn from data in Fischer & Miles,1973.)
in the performance of different crop planting patterns remained the same. In
an experiment with domestic oat and Avena fatua , Regnier & Bakelana (1995)
confirmed Fischer & Miles's (1973) assumption of radial expansion of plant
canopies, and found that the weeds grew larger as rectangularity increased.
Despite the strong theoretical basis for an inverse relation between row
spacing and weed growth, the effect of row spacing on weeds in the field has