Competition between autumn and spring planted grain intercrops of wheat (Triticum aestivum) and field bean (Vicia faba)

One winter wheat (Triticum aestivum)/field bean (Vicia faba) and two spring wheat/field bean intercrop field experiments for grain were planted on Wye College Farm, UR (51 degrees 11'N, 0 degrees 57'E) during the 1991, 1992 and 1993 seasons, respectively. The study site was managed conventionally and was of medium to high soil fertility for macronutrients. Land Equivalent Ratios (LER's) up 1.4 were achieved, suggesting up to a 40% grain yield increase for intercrops compared with sole crops. A comparison of winter and spring drilled wheat and bean intercrops indicated different key morphological and management factors. For the winter wheat, relative plant height was crucial. The older and taller cultivar Maris Widgeon grew better than the shorter Mercia in intercrops with the tall winter bran cultivar Bourdon. For the spring wheat and bean trials, weed competition resulted in the better performance of the wheat cultivar Canon than the bean cultivar Victor. Weed infestation in the spring intercrops was so high that its early and effective management was considered a key factor in their successful management. (C) 1999 Elsevier Science B.V. All rights reserved.