Enhancing the competitive ability of crops - Ecological Management of Agricultural Weeds - page 277

Figure 6.3 Biomass of(a) barley and (b) Sinapis alba grown in competition at several
densities.(Drawn from data in Håkansson,1983.)
response of yield to density is strictly increasing in the presence of weeds,
although yield shows a peaked curve in weed-free conditions (Table 6.1).
Thus, the response of yield to density is often qualitatively different in the
presence of weeds.
Other cultural practices interact with crop density in affecting weed and