Relationship between net blotch (Drechslera teres) and losses in grain yield of barley in Western Australia

1987 ◽  
Vol 38 (4) ◽  
pp. 671 ◽  
Author(s):  
TN Khan
Keyword(s):  
Critical Point ◽  
Western Australia ◽  
Yield Loss ◽  
Yield Reduction ◽  
Multiple Point ◽  
Net Blotch ◽  
Drechslera Teres ◽  
Percentage Yield ◽  
The Relationship ◽  
Common Equation

Losses in the yield of cv. Dampier due to net blotch (Drechslera teres (Sacc.) Shoem.) were examined in six environments in Western Australia. Based on comparison between least diseased and most diseased treatments, there was an overall yield reduction of 21% (P < 0.05). Three models (Critical Point, Area Under Curve and Multiple Point) were used to study the relationship between net blotch infection and percentage yield loss. All models gave similar results. Because of its simplicity, the Critical Point Model based on mean net blotch infection on the top three leaves at GS 75 was chosen. The percentage yield loss in cv. Dampier was defined to be 37% of the mean diseased area on leaves 1 (flag), 2 and 3 at GS 75. This relationship is very similar to that developed earlier for scald, and a common equation for both scald and net blotch was suggested.

Effect of spot-type net blotch (Drechslera teres (Sacc.) Shoem) infection on barley yield in short season environment of northern cereal belt of Western Australia

1989 ◽  
Vol 40 (4) ◽  
pp. 745 ◽  
Author(s):  
TN Khan
Keyword(s):  
Western Australia ◽  
Field Experiments ◽  
Yield Loss ◽  
Yield Response ◽  
Net Blotch ◽  
Drechslera Teres ◽  
Percentage Yield ◽  
Negative Effect ◽  
Short Season ◽  
Spot Type

The effect of spot-type net blotch (Drechslera teres (Sacc.) Shoem.) on yield was studied in fourteen field experiments located at two sites over seven years in the area where the disease occurs; the northern cereal belt of south-west Western Australia. An overall reduction of 26% in grain yield occurred associated with spot-type net blotch infection. The yield losses varied depending upon season, date of sowing and cultivar. Disease was found to reduce 100 grain weight and number of ears/m2, but number of grains/ear were not affected. Regression analysis supported the above negative effect of disease on yield in general, but in a few cases disease and yield were positively correlated. The Area Under Curve (AUC) model was considered most appropriate and percentage yield loss (L) was estimated as L = 0.0233 AUC. Using this relationship, potential losses in yields of cvv. Beeeher and O'Connor were estimated to be 34% and 29%, respectively. The application of this relationship is suggested to be limited to short season environments similar to the northern cereal belt of Western Australia. A need to understand factors which modify the yield response to this disease is highlighted.

Relationship between scald (Rhynchosporium secalis) and losses in grain yield of barley in Western Australia

1985 ◽  
Vol 36 (5) ◽  
pp. 655 ◽  
Author(s):  
TN Khan ◽  
MF D'Antuono
Keyword(s):  
Grain Yield ◽  
Critical Point ◽  
Western Australia ◽  
Field Experiments ◽  
Yield Loss ◽  
Growth Stages ◽  
Point Model ◽  
Percentage Yield ◽  
The Mean ◽  
Ripe Stage

The three commonly used techniques, viz. critical point model, area under the curve and multiple linear regression, were applied to study the relationship between scald infection and grain yield in field experiments conducted during 1979-1983 in Western Australia. In the preliminary analysis leaf three from the top and the mean of the top three leaves were found to be best correlated with yield. The three models did not dilfer greatly, presumably owing to the high correlations between scald at the milky ripe stage and at the earlier growth stages. The critical point model was chosen because of its simplicity. Percentage yield loss in combined data from all experiments showed a significant correlation (P < 0.001) with scald at the milky ripe stage and defined percentage yield loss in cultivars Clipper and Stirling to be about one-third of the mean scald damage on leaves 1 (flag), 2 and 3 at g.s. 75. Due to the range of trials in this analysis, it was suggested that this relationship may be applied to estimate yield loss from survey data in other parts of southern Australia, where scald is endemic.

Estimating yield losses in wheat resulting from infestation by doublegee (Emex australis)

1974 ◽  
Vol 14 (70) ◽  
pp. 656 ◽  
Author(s):  
DJ Gilbey
Keyword(s):  
Crop Yield ◽  
Field Trial ◽  
Yield Loss ◽  
Wheat Yield ◽  
Yield Reduction ◽  
Yield Losses ◽  
Seedling Mortality ◽  
Emex Australis ◽  
Percentage Yield

The effect of doublegee (Emex australis) density on wheat yield was studied in a field trial. Percentage yield reduction (y) was related to doublegee plants m-2 at 1 week (x1) and 8 weeks (x2) after seeding thus: y = 10.3 + 0.24 x1 r = 0.78*** y = 5.6 + 0.44 x2 r = 0.86*** showing that estimates of doublegee density could be used for forecasting crop yield losses before it is too late to spray. No further yield loss occurred when x1 was greater than 120 plants metre-2. Doublegee seedling mortality that occurred during the seven weeks between plant counts was strongly related to the initial counts (x1) thus: r = 0.88***.

Loss in Yield of Rapeseed (Brassica napus, B. campestris) Caused by Perennial Sowthistle (Sonchus arvensis) in Saskatchewan and Manitoba

Weed Science ◽  
1983 ◽  
Vol 31 (5) ◽  
pp. 740-744 ◽  
Author(s):  
Diether P. Peschken ◽  
A. Gordon Thomas ◽  
Robin F. Wise
Keyword(s):  
Brassica Napus ◽  
Survey Data ◽  
Yield Loss ◽  
Field Studies ◽  
Similar Frequency ◽  
A Value ◽  
Average Annual Loss ◽  
Percentage Yield ◽  
Sonchus Arvensis ◽  
The Relationship

Field studies were conducted in 1979 and 1980 to determine yield losses caused by perennial sowthistle (Sonchus arvensis L. # SONAR) in rapeseed (Brassica napus L., B. campestris L.) fields in Saskatchewan and Manitoba. The relationship between percentage yield loss and density of perennial sowthistle was expressed by the linear regression equation y = −3.81 + 13.76 rdx. Weed survey data indicated that perennial sowthistle occurred in 39% of the rapeseed fields but infested only 7% of the hectares surveyed. Using both the survey data and the yield loss equation, the average annual loss in rapeseed yield was estimated to be 9.4 million kg in Saskatchewan and 6.1 million kg in Manitoba, with a value of 2.6 million and 1.7 million dollars (Cdn.), respectively. Perennial sowthistle occurs with a similar frequency and density in other crops so that the total loss from this weed would be much greater.

Effects of stubble-borne fungal inoculum on incidence of leaf diseases and yields of barley in Western Australia

1988 ◽  
Vol 28 (4) ◽  
pp. 529 ◽  
Author(s):  
TN Khan
Keyword(s):  
Powdery Mildew ◽  
Yield Loss ◽  
Rhynchosporium Secalis ◽  
Net Blotch ◽  
Yield Losses ◽  
Hordeum Vulgare L ◽  
Leaf Disease ◽  
Drechslera Teres ◽  
Barley Crop ◽  
Number Of Seeds

Effect of stubble residues on leaf diseases and yield of barley (Hordeum vulgare L. cv. Dampier) were studied by adding small quantities of infested stubble to test plots grown on land where a non-barley crop or pasture had been grown in the previous year. Experiments conducted at 5 locations in 198 1 and 1982 showed that stubble residues increased leaf disease. The severity of leaf disease varied with location and year. High levels of scald (Rhynchosporium secalis) were recorded at all locations, but substantial levels of net blotch (Drechslera teres) occurred only at northern locations. Halo spot (Selenophoma donacis) and a leaf spot caused by Drechslera verticillata were either absent or occurred in minor proportions. The incidence of powdery mildew (Erysiphe graminis f.sp. hordei) at Mt Barker in 1982 was not related to the presence of stubble residues. Grain yield losses of 9 and 28% occurred in the stubble amended plots in 1981 and 1982, respectively. Reductions in number of heads and number of seeds per plot appeared to be the major components of yield loss.

Wheat (Triticum aestivum) yield reduction from common milkweed (Asclepias syriaca) competition

Weed Science ◽  
1997 ◽  
Vol 45 (1) ◽  
pp. 127-131 ◽  
Author(s):  
Joseph P. Yenish ◽  
Beverly R. Durgan ◽  
Douglas W. Miller ◽  
Donald L. Wyse
Keyword(s):  
Spring Wheat ◽  
Yield Loss ◽  
Root Function ◽  
Wheat Yield ◽  
Shoot Density ◽  
Yield Reduction ◽  
Square Root ◽  
Percentage Yield ◽  
Area Of Influence ◽  
Function Models

Yield loss of hard red spring wheat due to competition from common milkweed was measured in grower fields in Minnesota. Wheat yield loss was measured using the area of influence and additive competitive methods. Simple linear regression of wheat yield and percentage wheat yield loss against distance from a common milkweed shoot gaver2values of 0.013 and 0.015, respectively, indicating limited value of the area of influence model for common milkweed in spring wheat. In an additive competition model, wheat yield was reduced 47% at the highest density of 12 common milkweed shoots m−2. Coefficients of determination for percentage yield loss regressed against common milkweed shoot density were 0.548, 0.547, and 0.529 for simple linear, nonlinear rectangular hyperbolic, and linear square root function models, respectively. Regression of percentage yield loss against common milkweed biomass resulted inr2values of 0.566, 0.645, and 0.658 for simple linear, nonlinear rectangular hyperbolic, and linear square root function models, respectively. Restrictions of common milkweed density due to factors other than competition limited yield loss response to the simple linear phase of both the nonlinear rectangular hyperbolic and the linear square root function models previously described.

Relative time of redroot pigweed (Amaranthus retroflexusL.) emergence is critical in pigweed-sorghum [Sorghum bicolor(L.) Moench] competition

Weed Science ◽  
1997 ◽  
Vol 45 (4) ◽  
pp. 502-508 ◽  
Author(s):  
Stevan Z. Knezevic ◽  
Michael J. Horak ◽  
Richard L. Vanderlip
Keyword(s):  
Yield Components ◽  
Yield Loss ◽  
Polynomial Equation ◽  
Field Studies ◽  
Weed Density ◽  
Leaf Stage ◽  
Redroot Pigweed ◽  
Percentage Yield ◽  
Crop Growth Stage ◽  
The Relationship

Redroot pigweed is a common weed in sorghum fields throughout the southcentral United States including Kansas. In 1994 and 1995, field studies were conducted at two sites near Manhattan, KS, to determine the influence of redroot pigweed densities and times of emergence on sorghum yield and yield components. Redroot pigweed was sown at densities of 0.5, 1, 2, 4, and 12 plants meter−1of row within a 25-cm band over the sorghum row at planting and at the three- to four-leaf stage of sorghum. A rectangular hyperbola was used to describe the relationship between crop yield loss and weed density. Because of the instability of both coefficientsI(percentage yield loss at low weed density) andA(percentage yield loss at high weed density), our results do not support the use of a model based exclusively on weed number to estimate sorghum yield loss across all locations within a region. A quadratic polynomial equation that accounts for the time of weed emergence relative to the crop growth stage is suggested as an alternative method to estimate sorghum yield loss. At the densities studied, the time of pigweed emergence relative to the sorghum leaf stage was critical for the outcome of sorghum-pigweed competition. Significant sorghum yield losses occurred only when pigweed emerged before the 5.5-leaf stage of sorghum. An examination of yield components suggested that the yield loss was a result of a reduction in number of seeds per head.

Influence of Tartary Buckwheat (Fagopyrum tataricum) Density on Yield Loss of Barley (Hordeum vulgare) and wheat (Triticum aestivum)

Weed Science ◽  
1985 ◽  
Vol 33 (4) ◽  
pp. 521-523 ◽  
Author(s):  
E. Ann de St. Remy ◽  
John T. O'Donovan ◽  
Alan K. W. Tong ◽  
P. Ashley O'Sullivan ◽  
M. Paul Sharma ◽  
...  
Keyword(s):  
Triticum Aestivum ◽  
Hordeum Vulgare ◽  
Yield Loss ◽  
Plant Density ◽  
Wheat Yield ◽  
Tartary Buckwheat ◽  
Yield Reduction ◽  
Regression Equations ◽  
Fagopyrum Tataricum ◽  
The Relationship

The relationship between Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn. ♯ FAGTA) plant density (x) and percent yield loss (ŷ) was expressed by the following linear regression equations for barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.), respectively; ŷ = 0.63 + 2.75 √x and ŷ = 5.04 + 3.05 √x. Tartary buckwheat causes serious yield reduction in barley and wheat. A Tartary buckwheat density at 30 plants/m2 at emergence reduced barley yield by 16% and wheat yield by 22%.

Osmotic adjustment and seed yield of Brassica napus and B. juncea genotypes in a water-limited environment in south-western Australia

2003 ◽  
Vol 43 (9) ◽  
pp. 1127 ◽  
Author(s):  
S. R. Niknam ◽  
Q. Ma ◽  
D. W. Turner
Keyword(s):  
Seed Yield ◽  
Western Australia ◽  
Osmotic Adjustment ◽  
Seed Oil ◽  
Inverse Correlation ◽  
Yield Reduction ◽  
Physiological Trait ◽  
Water Deficits ◽  
Seed Fill ◽  
The Relationship

The relationship between osmotic adjustment and seed yield of Brassica oilseeds was examined at a low rainfall site, Merredin, Western Australia, in 1998 and 1999. Genotypes of B. napus and B. juncea were subjected to rain-fed and irrigated treatments at the seed-fill stage. The B. juncea lines showed small or even no yield reduction under rain-fed conditions, and generally had no yield advantage over the B. napus cultivars where irrigated. In both species, an inverse correlation was found between the magnitude of osmotic adjustment and the percentage of yield reduction. Genotypes with low osmotic adjustment, under rain-fed conditions, had a yield reduction of up to 40%, whereas those with high osmotic adjustment had only 0–10% yield reduction. In contrast, seed oil concentrations decreased from 41% under irrigation to 38% under water deficits and the differences among genotypes were not related to osmotic adjustment. In 1999, osmotic adjustment was again observed for most of the genotypes, but its association with seed yield was not as obvious as in the previous year and usually only the osmotically adjusting B. juncea genotypes maintained a good yield under water deficits. Not all the B. juncea genotypes expressed osmotic adjustment despite the fact that they were generally more drought resistant than the B. napus genotypes. In both years, however, osmotic adjustment was associated with increased harvest indices of B. napus and B. juncea, indicating that this physiological trait can be beneficial to Brassica yield in a water-limited Mediterranean-type environment.

Competition between wheat and brome grass in Western Australia

1987 ◽  
Vol 27 (2) ◽  
pp. 291 ◽  
Author(s):  
GS Gill ◽  
ML Poole ◽  
JE Holmes
Keyword(s):  
Western Australia ◽  
Soil Type ◽  
Field Experiments ◽  
Yield Loss ◽  
Wheat Yield ◽  
Exponential Model ◽  
Bromus Diandrus ◽  
Growing Conditions ◽  
Brome Grass ◽  
The Relationship

Brome grass (Bromus diandrus Roth) has become a serious weed of wheat in Western Australia, particularly on light textured soils. Six field experiments were carried out to investigate competition between brome grass and wheat. Results showed that brome grass is an extremely aggressive weed in wheat. Although the experimental sites varied considerably in soil type, rainfall and other growing conditions the relationship between brome grass and reduction in wheat yield was remarkably consistent across the sites. An exponential model was found to adequately describe yield loss due to competition with brome grass and will be used for extension purposes in Western Australia. An examination of yield contributing characters of wheat suggested that yield loss due to brome grass had been determined before the crop reached the grainfilling stage and such a result diminishes the importance of competition for water in wheat-brome grass mixtures.

Sign in / Sign up

Export Citation Format

Share Document