Effect of density and time of removal of volunteer canola (Brassica rapa L.) on yield loss of wheat (Triticum aestivum L.)

2008 ◽  
Vol 88 (4) ◽  
pp. 839-842 ◽  
Author(s):  
John T O'Donovan ◽  
K. Neil Harker ◽  
Donald A Dew
Keyword(s):  
Triticum Aestivum ◽  
Regression Analysis ◽  
Key Words ◽  
Brassica Rapa ◽  
Nonlinear Regression ◽  
Field Experiments ◽  
Yield Loss ◽  
Wheat Yield ◽  
Triticum Aestivum L ◽  
Nonlinear Regression Analysis

Field experiments were conducted at Lacombe, Alberta, in 1976, 1978, and 1979. Nonlinear regression analysis of the data indicated that initial slopes (% wheat yield loss at low canola densities) varied from 0.29% in 1979 to 2.44% in 1978. However, volunteer canola at densities of 47 (1976), 345 (1978), and 251 (1979) plants m-2 had little effect on wheat yield if the canola was removed at approximately 25 d or earlier after wheat emergence. Key words: Brassia rapa, volunteer canola density, time of weed removal

scholarly journals CANOLA YIELD AND PROFITABILITY AS INFLUENCED BY VOLUNTEER WHEAT INFESTATIONS

1989 ◽  
Vol 69 (4) ◽  
pp. 1235-1244 ◽  
Author(s):  
J. T. O’DONOVAN ◽  
K. J. KIRKLAND ◽  
A. K. SHARMA
Keyword(s):  
Triticum Aestivum ◽  
Multiple Regression ◽  
Seed Yield ◽  
Field Experiments ◽  
Yield Loss ◽  
Brassica Campestris ◽  
Triticum Aestivum L ◽  
Economic Threshold ◽  
Rectangular Hyperbola

The effects of different densities of volunteer wheat (Triticum aestivum L. ’Neepawa’) on the yield of canola (Brassica campestris L. ’Tobin’ and B. napus L. ’Westar’), and the seed yield of the volunteer wheat were determined in field experiments conducted at Vegreville, Alberta and Scott, Saskatchewan. Hyperbolic models provided a good fit to the data in most instances and indicated that volunteer wheat can severely reduce canola yield. A model pooled over locations and years indicated that volunteer wheat populations as low as one plant m−2 reduced canola yield by approximately 1%. Yield loss predictions from the models were used to determine the economics of volunteer wheat control with herbicides. In some cases, revenue losses due to reduced canola yield could be alleviated when the value of the volunteer wheat was considered.Key words: Volunteer wheat, canola, rectangular hyperbola, multiple regression, economic threshold, volunteer cereals

Effect of volunteer barley (Hordeum vulgareL.) interference on field pea (Pisum sativumL.) yield and profitability

Weed Science ◽  
1997 ◽  
Vol 45 (2) ◽  
pp. 249-255 ◽  
Author(s):  
John T. O'Donovan ◽  
Robert E. Blackshaw
Keyword(s):  
Regression Analysis ◽  
Seed Yield ◽  
Nonlinear Regression ◽  
Field Experiments ◽  
Plant Density ◽  
Barley Plant ◽  
Yield Losses ◽  
Nonlinear Regression Analysis ◽  
Economic Thresholds ◽  
Pea Seed

Relationships between volunteer barley plant density and both pea and volunteer barley yield were determined in field experiments conducted over 2 yr at Vegreville and Lethbridge, Alberta. Nonlinear regression analysis indicated that severe pea yield losses due to volunteer barley occurred at both locations. Averaged over both years, pea seed yield losses per volunteer barley plant (initial slopes) varied from 1.7% at Vegreville to 5.4% at Lethbridge. Based on certain assumptions, economic thresholds calculated from the equations were approximately 2 and 6 volunteer barley plants m−2at Lethbridge and Vegreville, respectively. Revenue from the volunteer barley seed partially alleviated the monetary losses caused by the reduced pea seed yield. The effects of pea density on pea and volunteer barley yield were inconsistent and marginal. This suggested that there was little advantage, in terms of increasing pea yield or reducing volunteer barley interference, to seeding pea above the recommended rate of 100 plants m−2.

EFFECTS OF VOLUNTEER WHEAT AND BARLEY ON THE GROWTH AND YIELD OF FLAX

1990 ◽  
Vol 70 (4) ◽  
pp. 1115-1122 ◽  
Author(s):  
LYLE FRIESEN ◽  
IAN N. MORRISON ◽  
GEORGE MARSHALL ◽  
WESLEY ROTHER
Keyword(s):  
Linum Usitatissimum ◽  
Field Experiments ◽  
Yield Loss ◽  
Triticum Aestivum L ◽  
Growth And Yield ◽  
Regression Equations ◽  
Nonlinear Regression Analysis ◽  
Hordeum Vulgare L ◽  
Linum Usitatissimum L ◽  
Intermediate Density

Field experiments were conducted in 1982 and 1983 to determine the effects of increasing densities (0–70 plants m−2) of volunteer wheat (Triticum aestivum L. Neepawa) and barley (Hordeum vulgare L. Bonanza) on the growth and seed yield of flax (Linum usitatissimum L. Dufferin). Rectangular hyperbolic models were fitted to data using nonlinear regression analysis. Results indicated that both volunteer cereals severely reduced flax biomass and yield, with volunteer barley interference causing greater losses than volunteer wheat at equivalent densities. From the regression equations it was calculated that an intermediate density of 30 volunteer wheat plants m−2 reduced the yield of flax by 49% in 1982 and 53% in 1983, whereas an equivalent density of volunteer barley plants reduced flax yields by 56% in 1982 and 67% in 1983.Key words: Competition, flax, volunteer wheat, volunteer barley, rectangular hyperbola, yield loss

Influence of the Relative Time of Emergence of Wild Oat (Avena fatua) on Yield Loss of Barley (Hordeum vulgare) and Wheat (Triticum aestivum)

Weed Science ◽  
1985 ◽  
Vol 33 (4) ◽  
pp. 498-503 ◽  
Author(s):  
John T. O'Donovan ◽  
E. Ann De St. Remy ◽  
P. Ashely O'Sullivan ◽  
Don A. Dew ◽  
Arvind K. Sharma
Keyword(s):  
Triticum Aestivum ◽  
Regression Analysis ◽  
Hordeum Vulgare ◽  
Significant Relationship ◽  
Field Experiments ◽  
Yield Loss ◽  
Avena Fatua ◽  
Regression Equations ◽  
Wild Oat ◽  
Relative Time

Multiple regression analysis of data from field experiments conducted in Alberta at two locations between 1972 and 1983 indicated that there was a significant relationship between yield loss of barley (Hordeum vulgareL.) and wheat (Triticum aestivumL.) and relative time of emergence of wild oat (Avena fatuaL. ♯ AVEFA). At a given wild oat density, percent yield loss increased the earlier wild oat emerged relative to the crops and gradually diminished the later it emerged. However, the magnitude of the yield loss for both species varied with the year. Regression equations based on data pooled over years and locations were developed to provide an estimate of yield loss of barley and wheat due to relative time of wild oat emergence and wild oat density. The information should be considered when barley and wheat losses due to wild oat are being assessed.

AC Helena spring wheat

2001 ◽  
Vol 81 (2) ◽  
pp. 277-279 ◽  
Author(s):  
H. G. Nass ◽  
L. P. Shugar ◽  
M. J. Etienne
Keyword(s):  
Triticum Aestivum ◽  
Powdery Mildew ◽  
Grain Yield ◽  
Key Words ◽  
Spring Wheat ◽  
Wheat Yield ◽  
Triticum Aestivum L ◽  
Lodging Resistance ◽  
Cultivar Description ◽  
High Level

AC Helena, a hard red spring milling wheat (Triticum aestivum L. em. Thell.) is adapted to Ontario and the Maritimes. It expressed high grain yield, lodging resistance, and a high level of resistance to powdery mildew. Key words: Triticum aestivum, red spring wheat, yield, cultivar description

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