Abstract:
To study the effects of plant density and ni
trogen rates on the ability of canola (Regent
×
Cobra; an inbred variety) to compete with weeds, an experiment was conducted as a
factorial complete block design with four replications. The treatments included four levels
of plant density at 150, 190, 230, and 270 plants m
-2
, and four levels of nitrogen (N) fertil-
izer at 0, 46, 92, and 138 kg ha
–1
. Results indicated that different levels of plant density
and N fertilizer had significant effects on the canola’s leaf area index (LAI) and dry mat-
ter accumulation, as well as on the weed’s dry matter at three stages of plant growth (ro-
sette, stem elongation, and 50% flowering).
The addition of N fertilizer resulted in in-
creasing plant LAI and decreasing weed dry
matter. Densities of 150 and 270 plants m
-2
,
along with 138 kg ha
–1
nitrogen showed the highest LAI at
the rosette and stem elongation
stages. The LAI at different plant growth stages was an important factor in enhancing ca-
nola’s competitiveness with weeds. There were significant differences between different
plant density and N fertilizer levels for traits
such as plant height, pod bearing stem
length, biomass and seed yield. An increase in plant density significantly decreased the
pod bearing stem length and total pod numbers per plant (i.e. pod numbers in main
branches and sub-branches), but increased plant height. The highest seed yield was ob-
tained with 190 plants m
-2
along with 138 kg N ha
–1
. This study revealed that optimum
plant density as well as N fertilizer may increa
se the competitive ability of canola against
weeds.
