scholarly journals Pratylenchus thornei: The Relationship Between Presowing Nematode Density and Yield Loss in Wheat and Barley

2020 ◽  
Vol 110 (3) ◽  
pp. 674-683 ◽  
Author(s):  
Joshua P. Fanning ◽  
Karyn L. Reeves ◽  
Clayton R. Forknall ◽  
Alan C. McKay ◽  
Grant J. Hollaway
Keyword(s):  
Grain Yield ◽  
Field Experiments ◽  
Economic Losses ◽  
First Year ◽  
Yield Losses ◽  
Nematode Density ◽  
Pratylenchus Thornei ◽  
Low Levels ◽  
The Relationship ◽  
Cereal Cultivars

The root lesion nematode Pratylenchus thornei causes economic losses in wheat and barley internationally through both reduced grain yield and grain quality. This study investigated the relationships between the presowing P. thornei density and grain yield and the postharvest nematode densities. Four field experiments were conducted at the same site between 2010 and 2014. A range of presowing P. thornei densities was established in the first year by growing three cereal cultivars that ranged from resistant to susceptible. In the following year, plots were sown with the five same cereal cultivars. A linear relationship was observed between the natural log of the presowing P. thornei density and grain yield across all seasons. The results showed that grain yield losses varied between cultivars and seasons. The importance of season was significant, with this study conducted over several seasons, and it highlighted the variability in yield losses between seasons, which will need further investigation. The greatest yield losses observed were 25 to 28% when the maximum presowing P. thornei densities ranged between 150 and 250 P. thornei g of soil−1. An analysis of the relationship between the presowing and postharvest nematode densities revealed that increased presowing nematode densities resulted in decreased multiplication rates in all seasons and in all cultivars. Nematode multiplication rates also varied between seasons. These results explain why it is difficult to predict nematode levels based on cropping history, and additionally, they highlight the importance of growing resistant cultivars to maintain low levels of P. thornei to minimize risk of yield losses.

scholarly journals The impact of cultivar resistance and fungicide treatment on mycotoxin content in grain and yield losses caused by Fusarium head blight in wheat

2010 ◽  
Vol 46 (No. 1) ◽  
pp. 21-26 ◽  
Author(s):  
V. Šíp ◽  
J. Chrpová ◽  
O. Veškrna ◽  
L. Bobková
Keyword(s):  
Grain Yield ◽  
Fusarium Head Blight ◽  
Field Experiments ◽  
Yield Loss ◽  
Joint Effect ◽  
Yield Losses ◽  
Cultivar Resistance ◽  
Head Blight ◽  
Fungicide Treatment ◽  
The Impact

Reactions to artificial infection with Fusarium graminearum isolates and a new fungicide Swing Top were studied in nine winter wheat cultivars evaluated in field experiments at two sites for three years for expression of symptoms, deoxynivalenol (DON) content in grain and grain yield. The results demonstrate a pronounced and relatively stable effect of cultivar resistance on reducing head blight, grain yield losses and contamination of grain by the mycotoxin DON. It is advantageous that the moderate level of resistance to Fusarium head blight (FHB) was detected also in two commonly grown Czech cultivars Sakura and Simila. Average fungicide efficacy for DON was 49.5% and 63.9% for a reduction in yield loss, however, it was found highly variable in different years and sites. The joint effect of cultivar resistance and fungicide treatment was 86.5% for DON and even 95.4% for reducing the yield loss. A very high risk was documented for susceptible cultivars and also the effects of medium responsive cultivars were found to be highly variable in different environments and therefore not guaranteeing sufficient protection against FHB under different conditions.

Yield response in chickpea cultivars and wheat following crop rotations affecting population densities of Pratylenchus thornei and arbuscular mycorrhizal fungi

2014 ◽  
Vol 65 (5) ◽  
pp. 428 ◽  
Author(s):  
R. A. Reen ◽  
J. P. Thompson ◽  
T. G. Clewett ◽  
J. G. Sheedy ◽  
K. L. Bell
Keyword(s):  
Grain Yield ◽  
Crop Rotation ◽  
Mycorrhizal Fungi ◽  
Soil Depth ◽  
Arbuscular Mycorrhizal ◽  
Yield Response ◽  
First Year ◽  
Pratylenchus Thornei ◽  
Tolerance Indices ◽  
Chickpea Cultivars

In Australia, root-lesion nematode (RLN; Pratylenchus thornei) significantly reduces chickpea and wheat yields. Yield losses from RLN have been determined through use of nematicide; however, nematicide does not control nematodes in Vertosol subsoils in Australia’s northern grains region. The alternative strategy of assessing yield response, by using crop rotation with resistant and susceptible crops to manipulate nematode populations, is poorly documented for chickpea. Our research tested the effectiveness of crop rotation and nematicide against P. thornei populations for assessing yield loss in chickpea. First-year field plots included canola, linseed, canaryseed, wheat and a fallow treatment, all with and without the nematicide aldicarb. The following year, aldicarb was reapplied and plots were re-cropped with four chickpea cultivars and one intolerant wheat cultivar. Highest P. thornei populations were after wheat, at 0.45–0.6 m soil depth. Aldicarb was effective to just 0.3 m for wheat and 0.45 m for other crops, and increased subsequent crop grain yield by only 6%. Canola, linseed and fallow treatments reduced P. thornei populations, but low mycorrhizal spore levels in the soil after canola and fallow treatments were associated with low chickpea yield. Canaryseed kept P. thornei populations low throughout the soil profile and maintained mycorrhizal spore densities, resulting in grain yield increases of up to 25% for chickpea cultivars and 55% for wheat when pre-cropped with canaryseed compared with wheat. Tolerance indices for chickpeas based on yield differences after paired wheat and canaryseed plots ranged from 80% for cv. Tyson to 95% for cv. Lasseter and this strategy is recommended for future use in assessing tolerance.

Yield responses of oats and alfalfa to common hemp-nettle (Galeopsis tetrahit) interference

1991 ◽  
Vol 71 (1) ◽  
pp. 141-147 ◽  
Author(s):  
Anne Légère ◽  
Jean-Marc Deschênes
Keyword(s):  
Field Experiments ◽  
First Year ◽  
Weed Competition ◽  
Yield Losses ◽  
Weed Interference ◽  
Medicago Sativa L ◽  
Lower Height ◽  
Carry Over ◽  
Yield Responses ◽  
Early Harvest

Effects of various densities of hemp-nettle (Galeopsis tetrahit L.) on yields of oats (Avena sativa L.) and first year alfalfa (Medicago sativa L.) were investigated in field experiments. In both crops, emergence of hemp-nettle seedlings occurred after plot establishment such that final densities were generally greater than initial densities. Hemp-nettle plants within a stand were distributed normally over no more than seven 15-cm height classes. Very few plants were found in the lower height classes. Weight distribution according to the same height classes showed that average to tall individuals produced a large proportion of the weed biomass. Oat yields decreased as hemp-nettle density increased. In the density range of 28–248 hemp-nettle plants m−2, oat grain yield losses varied between 12 and 50%. Alfalfa was cut according to either a two-cut regime, or a three-cut regime which included an early harvest. Alfalfa yields decreased with increase in hemp-nettle density regardless of cutting regime, whereas effects of cutting regime on alfalfa yield varied with year of experiment. In each regime, timing of first harvest determined the duration of hemp-nettle interference and may have affected the degree of carry-over effects to later harvests. Key words: Hemp-nettle, Galeopsis tetrahit, weed competition, weed interference, crop losses

scholarly journals Timing of Preharvest Infection of Pear Fruit by Botrytis cinerea and the Relationship to Postharvest Decay

Plant Disease ◽  
2004 ◽  
Vol 88 (5) ◽  
pp. 468-473 ◽  
Author(s):  
C. L. Lennox ◽  
R. A. Spotts
Keyword(s):  
Botrytis Cinerea ◽  
Gray Mold ◽  
Economic Losses ◽  
Pear Fruit ◽  
Full Bloom ◽  
Postharvest Decay ◽  
Poor Predictor ◽  
The Mean ◽  
Low Levels ◽  
The Relationship

Botrytis cinerea causes significant levels of postharvest decay in the winter pear cultivar d'Anjou. The objectives of this study were to determine the timing of B. cinerea infection of pear stems and calyxes in the orchard during the growing season, to investigate the development of gray mold in storage, and to determine whether preharvest levels of B. cinerea in pear stems and calyxes can be used as predictors of gray mold levels observed in storage. Very low levels of B. cinerea were isolated from stem tissue prior to harvest. In a single year repeat experiment, stems sampled at harvest had higher levels of infection than those sampled earlier in the season. Little or no stem end gray mold was detected in fruit after 3 months in air-storage; however, incidence increased between 6 and 8 months. Calyx end gray mold was detected at low levels in fruit stored for up to 8 months. The mean incidence of stem end gray mold was 3.6 and 2.0%, and incidence of calyx end gray mold was 1.2 and 0.2%, in 1996 and 1997, respectively. Calyxes were susceptible to infection soon after full bloom; however, inoculation of calyxes in April or May did not result in higher levels of calyx end gray mold in storage. Therefore, preharvest level of calyx infection is a poor predictor of calyx end gray mold in storage. In addition, application of benomyl in the orchard reduced the level of B. cinerea in blossoms but had no effect on levels of calyx end gray mold of fruit in storage. Packing and shipping fruit within 3 to 6 months of harvest may mitigate economic losses due to gray mold.

scholarly journals Response of the Most Promising Wheat Genotypes with Different Nitrogen Levels

2017 ◽  
Vol 4 (4) ◽  
pp. 489-497
Author(s):  
N. Rawal ◽  
D. Chalise ◽  
N. Khatri
Keyword(s):  
Grain Yield ◽  
Field Experiments ◽  
Limiting Factor ◽  
First Year ◽  
Wheat Genotypes ◽  
Ecological Zones ◽  
Nitrogen Levels ◽  
Silty Loam ◽  
Second Year ◽  
Plot Design

Field experiments were conducted during winter seasons of 2013 and 2014 on the alkaline and silty loam soils of NWRP, Bhairahawa to study the interaction of the most promising wheat genotypes with different nitrogen levels under different agro-ecological zones and recommend the appropriate dose of nitrogen for newly released varieties. The experiment was laid out in split plot design: four nitrogen levels (0, 50, 100 and 150 kg/ha) as a whole plot and six wheat genotypes (BL 3623, BL 3629, BL 3872, NL 1008, NL 1055 and Vijay) as a sub-plot which were replicated three times. There was significant effect of varieties and nitrogen levels on plant height, number of spikes, thousand grain weight and grain yield in both the years. In first year, the highest grain yield of 3.35 t/ha was obtained from the application of nitrogen @ 150 kg/ha with the genotype BL 3872 which is followed by the genotypes BL 3623 (3.15 ton/ha) and NL 1055 (3.05 ton/ha). Similarly in second year, the genotype NL 1055 gave the highest grain yield of 4.01 ton/ha followed by genotypes BL 3629 (3.83 ton/ha) and BL 3623 (3.81 ton/ha) from the application of nitrogen @ 150 kg/ha. Based on two years results, it can be concluded that N was a limiting factor in the productivity of wheat. Nitrogen @ 150 kg per ha produced higher yield and yield attributing characters. Similarly, the wheat genotypes NL 1055, BL 3629, BL 3623 and BL 3872 were superior among the genotypes.

Green Foxtail (Setaria viridis) and Pale Smartweed (Polygonum lapathifolium) Interference in Field Crops

1994 ◽  
Vol 8 (2) ◽  
pp. 311-316 ◽  
Author(s):  
John T. O'Donovan
Keyword(s):  
Crop Yield ◽  
Field Experiments ◽  
Dry Weight ◽  
Limiting Factor ◽  
Yield Losses ◽  
Weed Density ◽  
Green Foxtail ◽  
Polygonum Lapathifolium ◽  
And Control ◽  
The Relationship

Field experiments were conducted at Vegreville, Alberta in 1984, 1985, 1986, and 1988 to determine the effects of green foxtail and pale smartweed on yield of wheat, barley, and canola. There was considerable variation among years in the response of crop yield to both weeds and in the relationship between weed dry weight and weed density. Mostly relationships between crop yield and either weed density or dry weight were poor, suggesting that the weeds competed weakly with the crops. Thus density or dry weight may be poor predictors of crop yield losses due to green foxtail or pale smartweed. Where the crops emerged ahead of these weeds, and where soil moisture was not a limiting factor, crop yield losses were minimal and control with herbicides probably uneconomical. In some instances, growth and development of the weeds was suppressed by the crops to the extent that little or no weed dry matter was present at crop maturity. This was most evident with barley, and where the crops emerged ahead of the weeds.

Effect of Ascochyta blight on the grain yield of field peas (Pisum sativum L.) grown in southern Australia

1995 ◽  
Vol 35 (4) ◽  
pp. 531 ◽  
Author(s):  
TW Bretag ◽  
PJ Keane ◽  
TV Price
Keyword(s):  
Grain Yield ◽  
Disease Severity ◽  
Field Experiments ◽  
Ascochyta Blight ◽  
Crop Loss ◽  
Yield Losses ◽  
Crop Losses ◽  
Effective Strategies ◽  
Percentage Yield ◽  
Loss Models

Field experiments were conducted to determine the crop losses caused by ascochyta blight in different pea varieties grown in Victoria. For each variety, the reduction in yield associated with disease was determined by comparing grain yields in plots not sprayed with fungicide (disease present) and plots where the disease was controlled with fungicide sprays (no disease). There was considerable variation between pea varieties and lines in disease severity and crop losses. Individual varieties had different levels of tolerance to disease, and there were large differences between varieties in the percentage yield loss caused by the same level of disease. Disease severity was closely correlated with reductions in grain yield, and for most varieties there was a 5-6% reduction in grain yield for every 10% of stem area affected by disease (first 10 internodes on the main branch). Ascochyta blight caused substantial reductions in grain yield of all commercial pea varieties grown in Victoria but was usually most severe on the early-maturing varieties. For 15 varieties, empirical crop loss models to predict the relationship between disease severity and reduction in yield were developed. A disease survey of commercial crops was then conducted and estimates made of yield losses caused by ascochyta blight using the previously developed crop loss models. The estimated yield losses caused by ascochyta blight in commercial crops in Victoria in 1986 ranged from 3.1 to 26.4% and exceeded 15% in over three-quarters of crops surveyed. The results suggest that field pea production in Victoria is seriously retarded by ascochyta blight and that the development of effective strategies to control the disease should be given a high priority.

Response of field-grown maize to applied magnesium in acidic soils in north-eastern Australia

1999 ◽  
Vol 50 (2) ◽  
pp. 191 ◽  
Author(s):  
R. L. Aitken ◽  
T. Dickson ◽  
K. J. Hailes ◽  
P. W. Moody
Keyword(s):  
Grain Yield ◽  
Calcium Silicate ◽  
Field Experiments ◽  
Maize Yield ◽  
Yield Response ◽  
Eastern Australia ◽  
North Eastern ◽  
Lime Application ◽  
The Relationship ◽  
Gypsum Application

Split-plot field experiments, with main plots consisting of various rates of calcitic lime and single rates of dolomite, gypsum, and calcium silicate, were conducted at each of 4 sites to determine the effect of band-applied magnesium (Mg) on maize yield. The sites were acidic with pH values of 4.5, 4.9, 5.0, and 6.1 and exchangeable Mg levels of 0.16, 0.10, 6.0, and 2.0 cmol(+)/kg, respectively. Magnesium significantly (P < 0.05) increased grain yield at the 2 low-Mg sites, both of which were strongly acidic and responsive to lime application, but the nature of the Mg × lime interaction was different at each of the 2 responsive sites. The absence of a response to Mg at lime rates ≥1 t/ha at one responsive site was attributed to the presence of small amounts of Mg in the calcitic lime and/or an improved root environment enabling better exploitation of the soil Mg. Supplying a readily soluble source of Mg in the fertiliser band also resulted in increased grain yield in the gypsum, dolomite, and calcium silicate treatments at the 2 Mg-responsive sites. When the initial soil pH was strongly acidic, exchangeable Mg levels increased with increasing lime rate, suggesting that the small quantities of Mg that occur in the majority of liming materials may be of importance with respect to Mg nutrition. In contrast, gypsum application exacerbated the Mg deficiency at one site. The relationship between grain yield response and soil Mg level across all sites indicated that above an exchangeable Mg level of 0.27 cmol(+)/kg there would be little likelihood of a response to applied Mg.

Yield losses in canola in response to blackleg disease

2020 ◽  
Vol 100 (5) ◽  
pp. 488-494
Author(s):  
Yixiao Wang ◽  
Stephen E. Strelkov ◽  
Sheau-Fang Hwang
Keyword(s):  
Disease Severity ◽  
Field Experiments ◽  
Leptosphaeria Maculans ◽  
Economic Benefits ◽  
Control Measures ◽  
Yield Losses ◽  
Blackleg Disease ◽  
Brassica Napus L ◽  
Moderately Resistant ◽  
The Relationship

Blackleg, caused by Leptosphaeria maculans (Desm.) Ces. & De Not., is an important disease of canola (Brassica napus L.) worldwide. In Canada, blackleg is managed mainly by the cultivation of resistant or moderately resistant canola hybrids. Field experiments were conducted in Edmonton, AB, Canada, in 2017 and 2018 to determine the relationship between blackleg disease severity and yield in the moderately resistant canola hybrids ‘73-15RR’ and ‘1950RR’. Blackleg severity was rated on a 0–5 scale, where 0 = no disease and 5 = plant death. Regression analysis showed that relationships between disease severity and pod number and seed yield were best explained by second-degree quadratic equations in all site-years for both cultivars. Percentage yield loss increased by 18%–99% and 26%–86% in plants of ‘73-15RR’ and ‘1950RR’, respectively, with disease severities of 2–5 compared with plants with severities of 0–1. An improved knowledge of the relationship between blackleg severity and yield losses is important for a more accurate evaluation of the agronomic efficacy and economic benefits of control measures.

Studies on the nitrogenous manuring of winter wheat

1965 ◽  
Vol 65 (3) ◽  
pp. 379-387 ◽  
Author(s):  
J. L. Beveridge ◽  
R. H. Jarvis ◽  
W. J. Ridgman
Keyword(s):  
Environmental Factors ◽  
Winter Wheat ◽  
Grain Yield ◽  
Yield Components ◽  
Field Experiments ◽  
Regression Coefficients ◽  
Partial Regression ◽  
Optimum Time ◽  
The Relationship

1. The problem of when to apply nitrogenous top-dressings to winter wheat has nover been satisfactorily solved. Detailed field and glasshouse experiments on the effects of nitrogenous manuring on the development of wheat plants, and a number of other experiments involving the nitrogenous manuring of wheat are described and the results discussed.2. Partial regression coefficients of grain yield on individual components of yield are used to show how variable is the relationship between grain yield and the components of yield.3. It is concluded that field experiments are never likely to determine an optimum time for nitrogen top-dressing because of the unpredictable relationships between individual yield components and grain yield, and because of the variation in response to nitrogen introduced by seasonal and environmental factors.

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