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

RESPONSE OF SOYBEAN TO LOWER-CANOPY DEFOLIATION DURING SEEDFILL

1989 ◽  
Vol 69 (1) ◽  
pp. 17-22 ◽  
Author(s):  
B. L. VASILAS ◽  
J. FUHRMANN ◽  
L. E. GRAY
Keyword(s):  
Yield Components ◽  
Field Experiments ◽  
Total Yield ◽  
Brown Spot ◽  
Yield Losses ◽  
Growing Seasons ◽  
Naturally Occurring ◽  
Yield And Yield Components ◽  
Yield Responses ◽  
Pod Number

One of the effects of Septoria brown spot on soybean is accelerated lower-canopy defoliation. Field experiments were conducted in 1986 and 1987 to determine the response of soybean yield and yield components to progressive lower-canopy defoliation during seedfill. Soybean cultivar Williams 82 was machine planted in rows 76 cm wide and hand thinned to a uniform stand of 23 plants m−1. Three treatments were used: controls; defoliated, starting at R5 (beginning seed stage; DEF1), and defoliated, starting 7 d past R5 (DEF2). Defoliation treatments were applied by removing the leaflets and petioles from the lowest three or four leaf-bearing nodes four times at 4-d intervals so that only three or four nodes at the top of the plant remained leaf-bearing when defoliation ceased. Yield and yield components were determined for upper, lower and total nodes. Although the two growing seasons were very different, yield responses to defoliation were similar in both years. On the average, DEF1 reduced seed yield by 18% which is similar to losses that occur when brown spot is induced by inoculation; DEF2 reduced yields by 9% which is similar to yield losses reported for naturally occurring brown spot. Yields of DEF2 exceeded yields of DEF1 because of differences in pod number in 1986 and seeds/pod in 1987. Controls out-yielded DEF2 because of differences in seeds/pod in 1986 and seed size in 1987. The proportion of the total yield contributed by pods found on the upper nodes averaged 76% and was not affected by defoliation.Key words: Glycine max, Septoria glycines, brown spot, leaf loss

scholarly journals THE EFFECTS OF WEED INTERFERENCE: IN NEWLY PLANTED VINEYARDS

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1145a-1145
Author(s):  
Harry S. Agamalian
Keyword(s):  
Sandy Loam ◽  
Chenopodium Album ◽  
Sprinkler Irrigation ◽  
First Year ◽  
Weed Competition ◽  
Yield Data ◽  
Weed Interference ◽  
Vine Growth ◽  
Preemergence Herbicides ◽  
Grape Varieties

Initial weed competition in newly planted grapevines can delay vine development, resulting in reduced first harvest. The experiments were conducted over a three year period on three wine grape varieties: Chardonnay, Semillon, and Napa Gamay.Dormant rooted plants were winter planted and subjected to soil applied preemergence herbicides. The experiment was conducted on a Greenfield sandy loam under sprinkler irrigation. Major weeds were little mallow (Malva pariflora), hairy nightshade (Solanum sarachoides), lambsquarters (Chenopodium album), and Russian thistle (Sasola iberica).Vine growth was evaluated on cane weights, cane diameter, and cane length. Weed interference over the three year period resulted in 50% reduction in vine growth the first year. Yield data obtained from the third year resulted in significant differences between the weed free vines compared to the non-weeded treatments.

CRITICAL PERIOD OF WEED INTERFERENCE IN FIELD-SEEDED TOMATOES AND ITS RELATION TO WATER STRESS AND SHADING

1987 ◽  
Vol 67 (2) ◽  
pp. 575-583 ◽  
Author(s):  
S. E. WEAVER ◽  
C. S. TAN
Keyword(s):  
Water Stress ◽  
Lycopersicon Esculentum ◽  
Weed Control ◽  
Critical Period ◽  
Weed Competition ◽  
Yield Losses ◽  
Weed Interference ◽  
Light Levels

The critical period of weed interference in field-seeded tomatoes (Lycopersicon esculentum L. ’TH 318’) was determined in 1981, 1982 and 1983. The minimum weed-free period varied among years from 7 to 9 wk after sowing, while the maximum weed-infested period varied from 5 to 6 wk after sowing. A minimum of two weed control operations during the critical period was required to prevent yield losses. Reductions in tomato yields were correlated with weed dry weights and could be attributed both to reductions in light levels due to shading and weed competition for water which resulted in stomatal closure.Key words: Competition, critical period, weed, tomato, Lycopersicon esculentum L.

Influence of Cotton (Gossypium hirsutum) and Soybean (Glycine max) Planting Date on Weed Interference

Weed Science ◽  
1994 ◽  
Vol 42 (1) ◽  
pp. 61-65 ◽  
Author(s):  
Tracy E. Klingaman ◽  
Lawrence R. Oliver
Keyword(s):  
Field Experiments ◽  
Yield Loss ◽  
Planting Date ◽  
Cotton Yield ◽  
Yield Losses ◽  
Seed Cotton ◽  
Weed Species ◽  
Planting Dates ◽  
Seed Cotton Yield ◽  
Weed Interference

Separate field experiments were conducted for cotton and soybean in 1990 and 1991 to determine the influence of planting date on yield loss due to interspecific interference from entireleaf morningglory and sicklepod and to determine the relative competitiveness of each weed species. Percent soybean yield loss due to weed interference increased as planting date was delayed from early May to early June. Averaged over weed species, yield losses from 1.7 weeds m−1row were 10, 18, and 20% for soybeans planted in early May, mid-May, and early June, respectively. Yield loss from 6.7 weeds m−1row were 17, 31, and 35% at the early May, mid-May, and early June planting dates, respectively. Percent seed cotton yield losses averaged over weed species in 1990 were 33 and 28% for the early May and early June planting dates, respectively, at 1.7 weeds m−1and 50% for both planting dates at weed densities of 6.7 plants m−1. The only experimental factor that significantly affected seed cotton yield in 1991 was weed density. Unlike soybeans, planting date had little effect on weed interference in cotton. Entireleaf morningglory was more competitive than sicklepod in both crops. Results suggest that selection of optimum soy bean planting dates may be a viable means of reducing losses due to weed interference.

Weed interference reduces yield of coppiced tea tree (Melaleuca alternifolia)

2000 ◽  
Vol 40 (8) ◽  
pp. 1157
Author(s):  
J. G. Virtue ◽  
B. G. Sutton ◽  
G. J. Murtagh ◽  
R. D. Cousens
Keyword(s):  
Field Experiments ◽  
Yield Loss ◽  
Biomass Yield ◽  
Leaf Biomass ◽  
Yield Losses ◽  
Melaleuca Alternifolia ◽  
Tea Tree ◽  
Weed Interference ◽  
Leaf Oil ◽  
Oil Concentration

The effects of weeds on the oil yield of tea tree, Melaleuca alternifolia (Maiden and Betche) Cheel, were examined in 6 field experiments. Tea tree is grown in plantations as a coppice crop, being annually harvested for its leaf oil. Plots were maintained with and without weed control between successive harvests. Weed interference significantly reduced leaf biomass yield of regrowth tea tree in 5 of 6 experiments, with a mean yield loss of 25%. Yield losses ranged from 9 to 47%, and these were correlated with weed biomass remaining at harvest. Weed interference did not significantly affect leaf oil concentration, or its chemical composition.

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.

Use of Ecophysiological Models for Crop-Weed Interference: The Critical Period of Weed Interference

Weed Science ◽  
1992 ◽  
Vol 40 (2) ◽  
pp. 302-307 ◽  
Author(s):  
S. E. Weaver ◽  
M. J. Kropff ◽  
R.M.W. Groeneveld
Keyword(s):  
Critical Period ◽  
Weather Conditions ◽  
Weed Competition ◽  
Yield Losses ◽  
Early Season ◽  
Weed Density ◽  
Weed Interference ◽  
Crop Weed Competition ◽  
Mechanistic Simulation ◽  
Good Agreement

The performance of a mechanistic simulation model of crop-weed competition was tested with data on the critical period of weed competition in sugarbeets and both seeded and transplanted tomatoes. In general, there was good agreement between simulated and observed yields for different periods of weed interference in each crop. The model was then used to evaluate the influence of weed density, weed height, and weather conditions on timing of the critical period. Simulations suggested that the greater the weed density, the shorter the period of time that the crop could tolerate early-season competition, and the longer the period of time that the crop must be kept weed free to prevent yield losses. Simulations also suggested that the length of time that a crop can tolerate early-season weed competition is related more to the availability of soil moisture, or possibly essential nutrients, than to light limitations.

scholarly journals Flower Abscission and Induction in North American Ginseng with Ethephon

HortScience ◽  
2005 ◽  
Vol 40 (1) ◽  
pp. 138-141 ◽  
Author(s):  
Andrea E. Fiebig ◽  
J.T.A. Proctor ◽  
D.P. Murr ◽  
R.D. Reeleder
Keyword(s):  
North American ◽  
Field Experiments ◽  
American Ginseng ◽  
Tween 20 ◽  
First Year ◽  
Root Weight ◽  
Traditional Practice ◽  
Second Year ◽  
Carry Over ◽  
Carry Over Effect

Field experiments over 2 years were used to determine the effect of ethephon on: plant growth, weight of berries, proportion of red, green and immature berries, and root weight (economic yield) of 3-year-old north american ginseng plants (Panax quinquefolius L.). Ethephon sprays applied during bloom that thoroughly wetted the foliage and inflorescences immediately induced crop canopy descent (epinasty) exposing inflorescences and subsequently reducing plant height. Within a week the desired inflorescence and peduncle browning and flower drop took place. In each of four experiments ethephon, over the range 500 to 4000 mg·L-1, reduced berry weight and percent red berries, and increased the percent immature berries linearly. However, the responses to ethephon were variable. The highest concentration of 4000 mg·L-1 ethephon caused similar results in both years to the traditional practice of hand removal of inflorescences, but foliar reddening and some defoliation were observed. Buffering ethephon sprays at pH 2.6, 4.0, 5.0, and 6.0 gave similar results. The surfactant Tween 20 did not increase the effectiveness of the sprays. Generally, multiple applications of ethephon at lower concentrations were no more effective than comparable single higher concentration sprays. Carry-over effect of ethephon in the second year included crop stunting, an increase in root weight, and berry weights and berry color proportions similar to those plants on which hand removal was carried out in the first year. Chemical names used: 2-chloroethyl phosphonic acid (ethephon).

INFLUENCE OF THE DIFFERENT SOIL PREPARATION METHODS ON THE PEA YIELD

2018 ◽  
pp. 16-20
Author(s):  
А. М. Grebennikov ◽  
А. S. Frid ◽  
V. P. Belobrov ◽  
V. А. Isaev ◽  
V. М. Garmashоv ◽  
...  
Keyword(s):  
Field Experiments ◽  
Morphological Properties ◽  
Mineral Fertilizers ◽  
First Year ◽  
Zero Tillage ◽  
Preparation Methods ◽  
Soil Preparation ◽  
Multifactor Analysis ◽  
The Impact ◽  
Central Chernozem

The article assesses the relationships between the morphological properties of agrochernozems and yield of peas on the plots, experience with different methods of basic treatment (moldboard plowing at the depth of 20 - 22, 25 - 27 and 14 - 16 cm, moldboard plowing to a depth of 14 - 16 cm, combined midwater moldboard, mid-water subsurface, surface to a depth of 6 - 8 cm and zero tillage) is inherent in V.V. Dokuchaev Research Institute of Agriculture of the Central Black Earth strip, in the fall of 2014. The research was conducted in 2015 - 2016, with the application of mineral fertilizers (N60Р60К60) and unfertilized background. The highest pea yields in the fertilized as the background, and without the use of fertilizers was observed in dumping plowing and especially in the variant with deep moldboard plowing, which creates in comparison with other ways of handling the best conditions for the growth and development of peas. The lowest yield of pea was obtained with zero processing. Apparently legalistic migrational-mizelial agrochernozems the Central Chernozem zone of minimum tillage in the cultivation of peas are not effective, what is evident already in the first year after the laying of experience with different basic treatments. As shown by the results of applying multifactor analysis of variance studied the mapping properties of the soil can have the same significant impact on the yield of agricultural crops, as options for the field experiments aimed at assessing the impact of various treatments on yield.

Common Bermudagrass (Cynodon dactylon) Interference in Newly Planted Peach (Prunus persica) Trees

Weed Science ◽  
1985 ◽  
Vol 33 (1) ◽  
pp. 50-56 ◽  
Author(s):  
Stephen C. Weller ◽  
Walter A. Skroch ◽  
Thomas J. Monaco
Keyword(s):  
Field Experiments ◽  
Prunus Persica ◽  
Cynodon Dactylon ◽  
Ground Cover ◽  
First Year ◽  
Allelopathic Effect ◽  
Trunk Diameter ◽  
Leaf Chlorophyll ◽  
Tree Leaf ◽  
Common Bermudagrass

Field experiments conducted over a 2-yr period demonstrated that common bermudagrass [Cynodon dactylon (L.) Pers. # CYNDA] inhibited growth of newly planted peach (Prunus persica L. ‘Norman’) trees. Common bermudagrass densities of 100, 75, 50, and 25% ground cover reduced tree fresh weight by 86, 64, 43, and 19%, respectively, the first year (1978) and 87, 62, 44, and 28%, respectively, the second year (1979) after planting. Tree trunk diameter relative growth rate (RGR) was reduced by 75 and 100% common bermudagrass ground cover densities at all measurement dates only in 1978. Tree leaf N and K were reduced in both years by common bermudagrass; however, only at the 100% common bermudagrass density in 1978 was N at a deficient level. Leaf chlorophyll was reduced in trees grown in all densities of common bermudagrass only in 1978. Reduced tree growth cannot be explained entirely by competition for essential nutrients; thus an allelopathic effect of the bermudagrass on young peach roots is suspected.

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