New Zealand Journal of Crop and Horticultural Science abstracts
Weed flora of cereal crops in Canterbury, New Zealand
G. W. BOURDÔT
G. A. HURRELL
D. J. SAVILLE
New Zealand Pastoral Agriculture
Research Institute Limited
P. O. Box 60
Lincoln, New Zealand
Abstract Weed communities in Canterbury, New Zealand, cereal
crops were characterised in the 1990-91, 1991-92, and 1992-93 growing seasons
by measuring species population densities and harvest-time biomass in 39 and 45
fields respectively of wheat (
Triticum aestivum) and barley (
Hordeum
vulgare) in the absence of herbicide treatments. A total of >57 species
in >49 genera were recorded representing a total of 23 families with
Asteraceae, Brassicaceae, Caryophyllaceae, Fabaceae, Poaceae, and Polygonaceae
predominating. Annuals were more common (29 taxa) than perennials (12 taxa)
whereas biennials (4 taxa) were least frequent. Seven species occurred in
>50% of young crops:
Trifolium sp. (mainly
T. repens) (94% of
crops),
Capsella bursa-pastoris (85%),
Viola arvensis (69%),
Stellaria media (69%),
Polygonum aviculare (67%),
Chenopodium
album (67%), and
Anagallis arvensis (63%). Weed population densities
varied greatly between species but there was less variation between years and
crop type. Above harvesting height at crop maturity, most weed species occurred
less frequently and just eight species occurred with a frequency >20%;
Polygonum convolvulus (34% of crops),
P. aviculare (33%),
Chenopodium album (28%), grasses (mainly
Elytrigia repens)
(28%),
Crepis sp. (mainly
C. capillaris) (26%),
Viola
arvensis (23%),
Sonchus oleraceus (21%), and
Vicia sp. (21%).
Weeds above harvesting height occurred more frequently in wheat than in barley
and their biomass was on average, greater in the wheat crops. The numbers of
weed species per field varied from 6 to 16 and there was a strong trend toward
co-dominance by several species.
Keywords weed; flora; community; frequency; dominance;
biomass; population density; wheat; barley
H98006
Received 5 February 1998; accepted 2 July 1998
PDF file of entire paper: medium quality (1063K); (scanned from paper original: notes about this process)
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