Weed competitive ability of green peas (Pisum sativum L.) affected by seeding rate and genotype characteristics

K. Grevsen

Abstract
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 competitive ability.

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 growing peas.

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.


Source
Biological Agriculture and Horticulture (2003) 21: 247-261


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