scholarly journals Dry Bean Morpho-Physiological Responses to Gradual Weed Biomass Accumulation

2013 ◽  
Vol 5 (1) ◽  
pp. 74-78
Author(s):  
Hossein GHAMARI ◽  
Goudarz AHMADVAND
Keyword(s):  
Biomass Accumulation ◽  
Physiological Traits ◽  
Weed Competition ◽  
Dry Matter Accumulation ◽  
Dry Bean ◽  
Weed Biomass ◽  
Weed Interference ◽  
Free Treatment ◽  
Crop Cycle ◽  
Number Of Branches

Field study was carried out in 2011 in west of Iran to assess responses of dry bean (Phaseolus vulgaris L.) morpho-physiological traits to gradual weed biomass accumulation. The treatments consisted of two different periods of weed interference, which weeds either infested the plots or removed for an increasing duration of time (0, 10, 20, 30, 40, 50 days) after crop emergence. Relative dominance and relative importance of weed species fluctuated over the crop cycle. As the duration of weed interference was increased, a declining trend of crop growth rate (CGR) was observed. When weeds were allowed to compete with crop throughout the crop cycle, maximum value of CGR was decreased from 25.57 g m-2 days in full season weed free treatment to 16.78 g m-2 days in full season weed infested treatment. Effect of treatments on leaf area index (LAI) was significant. Weed removal increased LAI but it could not significantly affect this trait, at the early of growing season. Weed interference caused a significant reduction on number of branches. The minimum number of branches was registered in full season weed infested treatment (2.58 branches per plant), while the maximum one was observed in the full season weed free treatment (4.25 branches per plant). Weed competition severely reduced crop yield. At 10 and 20 days after crop emergence, weed infestation could not significantly affect the yield. A negative relationship between weeds’ dry matter accumulation and LAI as well as number of branches was observed which signify the vulnerability of these morpho-physiological traits to weed competition.

scholarly journals Growth Analysis of Dry Bean (Phaseolus vulgaris L.) in Different Weed Interference Situations

2013 ◽  
Vol 5 (3) ◽  
pp. 394-399 ◽  
Author(s):  
Hossein GHAMARI ◽  
Goudarz AHMADVAND
Keyword(s):  
Dry Matter ◽  
Growth Analysis ◽  
Yield Loss ◽  
Growing Season ◽  
Crop Growth ◽  
Weed Competition ◽  
Dry Matter Accumulation ◽  
Dry Bean ◽  
Weed Interference ◽  
Crop Biomass

In production agriculture, weed plants play an important role in yield reduction. Analysis of crop growth can reveal underlying processes of yield loss under weed interference conditions. Therefore, an experiment was conducted in 2011 in order to assess the effect of weed competition on different aspects of dry bean growth. The experiment was a randomized complete block design with 3 replications. Treatments included weed-infested and weed-free periods until 0, 10, 20, 30, 40 and 50 days after crop emergence. Aboveground dry matter and leaf area were measured every two weeks. The functional approach to growth analysis was used to examine temporal patterns in crop growth in weed interference conditions. A negative relationship between weed biomass and dry bean growth indexes was observed. In all treatments, crop biomass had a similar trend and progressively increased over the crop cycle, then after reaching the maximum amount, gradually decreased. The lowest crop biomass (676.60 g m-2) was observed in season-long weed-infested treatment, while the maximum one (1238.82 g m-2) was recorded in season-long weed-free treatment. Relative growth rate (RGR) and net assimilation rate (NAR) had a declining trend during the growing season. Increase in weed-infested periods intensified decrease of them. Effect of weed competition on crop growth was trifle at the early of growing season. Since NAR and RGR represent photosynthesis potential and dry matter accumulation of the crop, their reduction can be the main cause of yield loss.

scholarly journals Weed Interference Affects Dry Bean Yield and Growth

2012 ◽  
Vol 4 (3) ◽  
pp. 70-75 ◽  
Author(s):  
Hossein GHAMARI ◽  
Goudarz AHMADVAND
Keyword(s):  
Chenopodium Album ◽  
Growing Season ◽  
Amaranthus Retroflexus ◽  
Growth And Yield ◽  
Weed Competition ◽  
Weed Species ◽  
Dry Bean ◽  
Logistic Equations ◽  
Weed Interference ◽  
Minimum Number

Dry bean is one of the most important pulse crops in Iran. Field study was conducted in 2011 to evaluate effects of weed competition from a natural flora on growth and yield of dry bean (Phaseolus vulgaris L.). The treatments consisted of weed infestation and weed removal periods (10, 20, 30, 40 and 50 days) after crop emergence. Control plots kept weed-infested and weed-free throughout growing season. To assess the weed competition effect on crop characteristics, Richards, Gompertz and logistic equations were fitted to the data. The most abundant weed species were Chenopodium album and Amaranthus retroflexus. Increase in duration of weed interference decreased the stem height of dry bean. At the end of the growing season, dry bean was 20 cm taller in season-long weed-free treatment compared to the season-long weed-infested treatment. As the number of days of weed interference increased, a declining trend of LAI and number of pods was observed. The minimum number of pods was obtained in season-long weed-infested treatment (5.01 pods/plant). Weed interference during the whole growing season, caused a 60% reduction in yield. Considering 5% and 10% acceptable yield lost, the critical period of weed competition was determined from 20 to 68 and 23 to 55 days after planting (DAE), respectively.

Response of Corn Genotypes to Weed Interference and Nitrogen in Nigeria

Weed Science ◽  
2008 ◽  
Vol 56 (3) ◽  
pp. 424-433 ◽  
Author(s):  
David Chikoye ◽  
Ayeoffe F. Lum ◽  
Robert Abaidoo ◽  
Abebe Menkir ◽  
Alpha Kamara ◽  
...  
Keyword(s):  
Grain Yield ◽  
Chlorophyll Content ◽  
Yield Response ◽  
Weed Biomass ◽  
Weed Interference ◽  
Leaf Chlorophyll ◽  
Free Treatment ◽  
Main Plot ◽  
N Rates ◽  
N Pool

The effects of nitrogen (N) rate and weed interference on the grain yield of four corn genotypes were investigated in 2002 and 2003 at Ikenne (7°38′N, 3°42′E), Shika (11°11′N, 7°38′E), and Samaru (10°24′N, 7°42′E) in Nigeria. Nitrogen (N) at 0, 30, 60, and 90 kg N ha−1were the main plot treatments. Weed-free (weeded weekly), low (intrarow weeds only), and high (zero weeding) weed pressure were the subplot treatments. Four corn genotypes (ACR8328 BN C7, Low-N-Pool C2, Oba Super II, TZB-SR) were the sub-subplot treatments. Weed density was higher at Shika and Samaru than at Ikenne, and the order of average weed biomass 8 to 10 weeks after planting was Samaru (271 g m−2) > Ikenne (236 g m−2) > Shika (161 g m−2). Corn genotype and N rate had no effect on weed biomass except at Samaru where fertilized treatments had higher weed biomass than the unfertilized treatments. Corn leaf area (LA) increased with increasing N rate at all locations regardless of weed pressure and genotype, except at Shika where ACR8328 BN C7, Oba Super II, and TZB-SR did not show any clear N response; LA was highest in the weed-free and lowest in the unfertilized treatments for all genotypes and locations, and weed pressure treatments. Low-N-Pool C2had the highest LA, which was 1.3 times larger than in Oba Super II, which had the lowest LA. Nitrogen rate, weed pressure, and genotypes significantly affected corn leaf chlorophyll content. Chlorophyll content was higher in the fertilized treatments than the unfertilized treatments, and higher in the weed-free treatments than the low or high weed pressure treatments. ACR8328 BN C7and Oba Super II had significantly more chlorophyll than the other genotypes. Low-N-Pool C2showed a linear grain yield response with the increase in N rates. ACR8328 BN C7did not respond to N application. Compared with the results in the weed-free treatment, high weed pressure reduced grain yield in all genotypes by more than 65% at Samaru, 50% at Shika, and 35% at Ikenne.

scholarly journals Paclobutrazol Improves Sesame Yield by Increasing Dry Matter Accumulation and Reducing Seed Shattering Under Rainfed Conditions

2021 ◽  
Author(s):  
Muhammad Zeeshan Mehmood ◽  
Ghulam Qadir ◽  
Obaid Afzal ◽  
Atta Mohi Ud Din ◽  
Muhammad Ali Raza ◽  
...  
Keyword(s):  
Leaf Area ◽  
Seed Production ◽  
Seed Yield ◽  
Dry Matter ◽  
Biomass Accumulation ◽  
Total Biomass ◽  
Dry Matter Accumulation ◽  
Seed Shattering ◽  
Rainfed Conditions ◽  
Leaf Greenness

AbstractSeveral biotic and abiotic stresses significantly decrease the biomass accumulation and seed yield of sesame crops under rainfed areas. However, plant growth regulators (such as Paclobutrazol) can improve the total dry matter and seed production of the sesame crop. The effects of the paclobutrazol application on dry matter accumulation and seed yield had not been studied before in sesame under rainfed conditions. Therefore, a two-year field study during 2018 and 2019 was conducted with key objectives to assess the impacts of paclobutrazol on leaf greenness, leaf area, total dry matter production and partitioning, seed shattering, and seed yield of sesame. Two sesame cultivars (TS-5 and TS-3) were treated with four paclobutrazol concentrations (P0 = Control, P1 = 100 mg L−1, P2 = 200 mg L−1, P3 = 300 mg L−1). The experiment was executed in RCBD-factorial design with three replications. Compared with P0, treatment P3 improved the leaf greenness of sesame by 17%, 38%, and 60% at 45, 85, and 125 days after sowing, respectively. However, P3 treatment decreased the leaf area of sesame by 14% and 20% at 45 and 85 days after sowing than P0, respectively. Compared with P0, treatment P3 increased the leaf area by 46% at 125 days after sowing. On average, treatment P3 also improved the total biomass production by 21% and partitioning in roots, stems, leaves, capsules, and seeds by 23%, 19%, 23%, 22%, and 40%, respectively, in the whole growing seasons as compared to P0. Moreover, under P3 treatment, sesame attained the highest seed yield and lowest seed shattering by 27% and 30%, respectively, compared to P0. This study indicated that by applying the paclobutrazol concentration at the rate of 300 mg L−1 in sesame, the leaf greenness, leaf areas, biomass accumulation, partitioning, seed yield, and shatter resistance could be improved. Thus, the optimum paclobutrazol level could enhance the dry matter accumulation and seed production capacity of sesame by decreasing shattering losses under rainfed conditions.

The critical weed-free period in glyphosate-resistant soybean in Ontario is similar to previous estimates using glyphosate-susceptible soybean

2019 ◽  
Vol 99 (4) ◽  
pp. 437-443
Author(s):  
Nader Soltani ◽  
Robert E. Nurse ◽  
Amit J. Jhala ◽  
Peter H. Sikkema
Keyword(s):  
Growth Stage ◽  
Field Experiments ◽  
Yield Loss ◽  
Growth Stages ◽  
Weed Species ◽  
Weed Biomass ◽  
Weed Density ◽  
Weed Interference ◽  
Beginning Of Flowering ◽  
Minimal Reduction

A study consisting of 13 field experiments was conducted during 2014–2016 in southwestern Ontario and southcentral Nebraska (Clay Center) to determine the effect of late-emerging weeds on the yield of glyphosate-resistant soybean. Soybean was maintained weed-free with glyphosate (900 g ae ha−1) up to the VC (cotyledon), V1 (first trifoliate), V2 (second trifoliate), V3 (third trifoliate), V4 (fourth trifoliate), and R1 (beginning of flowering) growth stages, after which weeds were allowed to naturally infest the soybean plots. The total weed density was reduced to 24%, 63%, 67%, 72%, 76%, and 92% in Environment 1 (Exeter, Harrow, and Ridgetown) when soybean was maintained weed-free up to the VC, V1, V2, V3, V4, and R1 soybean growth stages, respectively. The total weed biomass was reduced by 33%, 82%, 95%, 97%, 97%, and 100% in Environment 1 (Exeter, Harrow, and Ridgetown) and 28%, 100%, 100%, 100%, 100%, and 100% in Environment 2 (Clay Center) when soybean was maintained weed-free up to the VC, V1, V2, V3, V4, and R1 stages, respectively. The critical weed-free periods for a 2.5%, 5%, and 10% yield loss in soybean were the V1–V2, VC–V1, and VC–V1 soybean stages in Environment 1 (Exeter, Harrow, and Ridgetown) and V2–V3, V2–V3, and V1–V2 soybean stages in Environment 2 (Clay Center), respectively. For the weed species evaluated, there was a minimal reduction in weed biomass (5% or less) when soybean was maintained weed-free beyond the V3 soybean growth stage. These results shows that soybean must be maintained weed-free up to the V3 growth stage to minimize yield loss due to weed interference.

scholarly journals Interference Periods in Soybean Crop as Affected by Emergence Times of Weeds

2018 ◽  
Vol 36 (0) ◽  
Author(s):  
R.R. ZANDONÁ ◽  
D. AGOSTINETTO ◽  
B.M. SILVA ◽  
Q. RUCHEL ◽  
D.S. FRAGA
Keyword(s):  
Weed Management ◽  
Critical Period ◽  
Block Design ◽  
Crop Productivity ◽  
Dry Mass ◽  
Weed Interference ◽  
Randomized Block Design ◽  
Intermediate Time ◽  
Crop Cycle ◽  
Weed Emergence

ABSTRACT: Weeds emergence times modify competition with crops. Thus, the hypothesis was that the increase in weed emergence flow decreases the period prior to interference (PPI) in soybeans and increases the critical period of interference prevention (CPIP). The objective was to determine the PPI and the CPIP of weeds in soybean crops as affected by the preferred time of weeds emergence flow. Three experiments were conducted in the field in a randomized block design with four replications. The treatments were arranged in a factorial design with factor A consisting of coexistence or weed control in soybeans and factor B for eight periods (0, 7, 14, 21, 28, 35, 42 and 135 days after crop emergence (DAE)). The numbers of emerged plants and weed dry mass by genus and crop productivity were evaluated. The weed interference in culture during all the crop cycle reduces the soybean average yield 73, 94 and 89% in the first, second and third sowing times, respectively. Chemical control may be adopted at the end of PPI, which must be done at 14, 15 and 5 DAE crop, for the first, second, third times, respectively. The sowing in advance and intermediate time of recommendation increase the PPI in about 10 days, favoring the weed management in soybean crops.

Simulation of Competition for Photosynthetically Active Radiation Between Common Ragweed (Ambrosia artemisiifolia) and Dry Bean (Phaseolus vulgaris)

Weed Science ◽  
1996 ◽  
Vol 44 (3) ◽  
pp. 545-554 ◽  
Author(s):  
David Chikoye ◽  
Leslie A. Hunt ◽  
Clarence J. Swanton
Keyword(s):  
Leaf Area ◽  
Crop Yield ◽  
Photosynthetically Active Radiation ◽  
Growth And Development ◽  
Field Studies ◽  
Weed Competition ◽  
Yield Losses ◽  
Dry Bean ◽  
Common Ragweed ◽  
Active Radiation

The influence of weeds on crop yield is not only dependent on weed-related factors such as density and time of emergence, but also on environmental and management factors that affect both the weed and crop through time. This study was undertaken to develop the first physiologically based dry bean model that would account for the influence of weed competition. The specific objective was to develop a model that would account for the influence of weed competition on crop yield, and to use this model to test the hypothesis that crop yield losses resulted from competition for photosynthetically active radiation (PAR). To this end, a model that simulated the growth and development of dry bean was developed. The model performed daily calculations and simulated the phenology, leaf area expansion, dry matter production and distribution, and grain yield of dry bean based on weather and management information, but assumed adequate water and nutrients. The model was calibrated without weed competition at two locations and yr, and for these situations, adequately described the growth and development of the crop. Simulations were then run for five common ragweed densities and two times of emergence. Common ragweed leaf area was read into the model from input files and used to simulate weed shading. Shading of the dry bean canopy by common ragweed accounted for about 50 to 70% of the yield losses observed in field studies when weeds emerged with the crop. Weed shading did not account for the yield reduction measured from weeds that emerged at the second trifoliate stage of crop growth. The agreement between model predictions and field studies was consistent with the hypothesis that competition for PAR was a principal factor in weed-crop interaction. The ability to account for differences in weed densities, management, and environmental conditions suggested that modeling was a useful tool for evaluating the interaction among weeds and crops.

scholarly journals The Impact of Herbicide Application and Defoliation on Barley Grass (Hordeum murinum subsp. glaucum) Management in Mixed Pasture Legumes

Agronomy ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 671
Author(s):  
Jane Kelly ◽  
Allison Chambers ◽  
Paul Weston ◽  
William Brown ◽  
Wayne Robinson ◽  
...  
Keyword(s):  
Seed Production ◽  
Weed Management ◽  
Seedling Emergence ◽  
Management Strategies ◽  
Biomass Accumulation ◽  
Integrated Weed Management ◽  
Wagga Wagga ◽  
Weed Biomass ◽  
Hordeum Murinum ◽  
The Impact

Barley grass (Hordeum murinum subsp. glaucum.) is an annual weed associated with grain revenue loss and sheep carcass damage in southern Australia. Increasing herbicide resistance led to a recent investigation into effective integrated weed management strategies for barley grass in southern Australia. Field studies in Wagga Wagga, New South Wales (NSW) during 2016 and 2017 examined the effect of post-emergent herbicide applications and strategic defoliation by mowing on barley grass survival and seed production in a mixed legume pasture. Statistically significant differences between herbicide-only treatments in both years showed propaquizafop to be more than 98% effective in reducing barley grass survival and seed production. Paraquat was not effective in controlling barley grass (58% efficacy), but led to a 36% and 63.5% decrease in clover and other weed biomass, respectively, after 12 months and increased lucerne biomass by over three-fold after 24 months. A single repeated mowing treatment resulted in a 46% decline in barley grass seedling emergence after 12 months and, when integrated with herbicide applications, reduced other weed biomass after 24 months by 95%. Resistance to acetyl-CoA carboxylase (ACCase)-inhibiting herbicides observed in local barley grass populations led to additional and more focused investigation comparing the efficacy of other pre- and post-emergent herbicides for barley grass management in legume pastures. Haloxyfop-R + simazine or paraquat, applied at early tillering stage, were most efficacious in reducing barley grass survival and fecundity. Impact of defoliation timing and frequency on barley grass seedlings was also evaluated at various population densities, highlighting the efficacy of repeated post-inflorescence defoliations in reducing plant survival and seed production. Results highlight the importance of optimal environmental conditions and application timing in achieving efficacious control of barley grass and improving pasture growth and biomass accumulation.

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

Shade Avoidance in Soybean Reduces Branching and Increases Plant-to-Plant Variability in Biomass and Yield Per Plant

Weed Science ◽  
2011 ◽  
Vol 59 (1) ◽  
pp. 43-49 ◽  
Author(s):  
Emily Green-Tracewicz ◽  
Eric R. Page ◽  
Clarence J. Swanton
Keyword(s):  
Light Quality ◽  
Biomass Accumulation ◽  
Field Trials ◽  
Weed Competition ◽  
Shade Avoidance ◽  
Internode Elongation ◽  
Yield Losses ◽  
Plant Yield ◽  
Reflected Light ◽  
Crop Weed Competition

Recent studies have suggested that soybeans express shade avoidance in response to low red : far-red (R : FR) light reflected from neighboring plants and that this response may determine the onset and outcome of crop–weed competition. We tested the hypothesis that the low R : FR ratio would trigger characteristic shade avoidance responses in soybean and that the subsequent phenotype would experience reproductive costs under non–resource-limiting conditions. Soybeans were grown in a fertigation system in field trials conducted in 2007 and 2008 under two light quality treatments: (1) high R : FR ratio (i.e., weed-free) i.e., upward reflected light from a baked clay medium (Turface MVP®), or (2) low R : FR ratio (i.e., weedy) of upward reflected light, from commercial turfgrass. Results of this study indicated that a reduction in the R : FR ratio of light reflected from the surface of turfgrass increased soybean internode elongation, reduced branching, and decreased yield per plant. Shade avoidance also increased the plant-to-plant variability in biomass and yield per plant. Per plant yield losses were, however, more closely associated with reductions in biomass accumulation than population variability as the expression of a shade avoidance response did not influence harvest index. While these results suggest that weed induced shade avoidance decreases soybean per plant yield by reducing branching, it is possible the productivity of a soybean stand as a whole may be buffered against these reduction by a similar, but opposite, expression of plasticity in branching.

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