Weed competitive ability of green peas (Pisum sativum L.)
affected by seeding rate and genotype characteristics
Field experiments were conducted in Denmark during 1997, 1998 and 2000
to study the effects of genotype and sowing rate on the competitive
ability of green pea crops against weeds in organic production.
In 1997/98, eight cultivars were tested under three sowing rates (90,
120 and 150 seeds/m2). The dry weight (DW) of the natural weed population
at harvest was used to measure competitive ability. In 2000, ten cultivars
were tested with one sowing rate (110 seeds/m2) and DW of an in-sown
weed crop of winter rape (Brassica napus) plants was used to measure
The competitive ability of the pea crop increased significantly when
the sowing rate was increased from 90 to 150 seeds/m2 in both years.
The reduction in weed DW due to increased sowing rate in 1997 and 1998
was 50 and 30%, respectively, but the increase in yield of peas was
only significant in one year.
There were significant differences between competitive ability of cultivars
in both experiments. The cultivars with high seed weight and with fast
early growth were more competitive than small-sized peas and slower
The correlations for seed weight were significant in both years when
certain plant types were excluded, but correlations for fast early growth
were only significant in one out of two years.
The cultivars with high biomass accumulation i.e. Ambassador, Greenshaft,
Jaguar, Zelda and DS8903 were highly competitive while the small -sized
pea cultivars i.e. Dinos, Argona and Wizard had low competitive ability
and were unsuitable for organic pea production.
Biological Agriculture and Horticulture (2003) 21: 247-261