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The experiment was conducted from November 2019 to February 2020 at the experimental site of the Federal University of Fronteira Sul (UFFS), Campus Erechim, RS, Brazil. The site is located in the physiographic region of Alto Uruguai, Rio Grande do Sul, Brazil, at geographical coordinates 27°43'47" S latitude and 52°17'37" W longitude and at an altitude of 760 m. The soil in the experimental area is classified as typical Ferric Alumino Red Oxisol[24] and the predominant climate in the region is Cfa according to the Koppen classification, i.e. humid subtropical, with hot summers and evenly distributed rainfall. The average temperature of the warmest month is above 22 °C, the rainfall is 1,100 to 2,000 mm, there are severe and frequent frosts with an average duration of ten to 25 d per year[25]. The weather conditions that occurred during the experiment are shown in Fig. 1.
Figure 1.
Average temperature (°C) and monthly precipitation (mm) during the experimental period, from November 2019 to February 2020. Source: INMET[26].
Figure 2.
Grain yield loss (GYL) of bean cultivars as a function of alexandergrass plant density 35 d after emergence. R2 = Coefficient of determination; MSR = mean square of residuals; * Significant at p ≤ 0.05.
Figure 3.
Grain yield loss (GYL) of bean cultivars as a function of alexandergrass soil cover 35 d after emergence. R2 = Coefficient of determination; MSR = mean square of the residuals; * Significant at p ≤ 0.05.
Figure 4.
Grain yield loss (GYL) of bean cultivars as a function of alexandergrass leaf area 35 d after emergence. R2 = Coefficient of determination; MSR = mean square of the residuals; * Significant at p ≤ 0.05.
Some physical and chemical properties of the soil were: pH in water 4.70; OM = 3.04%; P = 8.50 mg dm−3; K = 16.00 mg dm−3; Al3+ = 1.00 cmolc dm−3; Ca2+ = 5.10 cmolc dm−3; Mg2+ = 3.40 cmolc dm−3; CECeffective = 9.90 cmolc dm−3; CECpH7 = 18.60 cmolc dm−3; H+Al = 9.70 cmolc dm−3; base saturation = 48% and clay = 64%.
Experimental design
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The cropping method chosen was the no-till system with black oat and vetch straw (4.50 t ha−1), with the plot dried with glyphosate (1,080 g ha−1) 15 d before sowing. The experimental design was completely randomized, with treatments consisting of seven carioca bean cultivars and 12 alexandergrass densities, as shown in Table 1.
Table 1. Bean cultivars and alexandergrass densities (plants m−2) used in the experiment.
Bean cultivar Alexandergrass density (m−2) IAC Imperador 0, 56, 56, 80, 96, 108, 292, 292, 300, 380, 480 and 560 IPR Curió 0, 28, 40, 60, 60, 68, 68, 68, 80, 160, 180 and 200 ANFC9 0, 60, 68, 116, 160, 160, 200, 280, 300, 340, 368 and 480 IAC Milênio 0, 28, 32, 44, 48, 88, 128, 140, 148, 180, 184 and 232 IPR Tangará 0, 20, 52, 60, 64, 68, 100, 108, 116, 148, 160 and 240 IPR Sabiá 0, 40, 60, 68, 80, 92, 104, 112, 128, 148, 280 and 340 BRS Pérola 0, 28, 40, 56, 68, 80, 84, 128, 148, 160, 168 and 180 Since the alexandergrass that infested the bean plant came as spontaneous vegetation from the soil seed bank in the area where the experiment was conducted, the establishment of density was not the same for all cultivars. The lack of uniformity is due to factors such as infestation, vigor, moisture, and dormancy of the weed seeds, among others, which prevent the establishment of the same number of plants per area (experimental unit). However, to maintain the natural growing conditions, it was decided not to thin out the different densities of alexandergrass between the cultivars. To maintain the natural situation in the field, the weed densities of the different cultivars were also not changed in other studies investigating similar situations to the present study[8,11,19,27,28]. The bean cultivars were selected because they are the most commonly grown in Brazil. Their characteristics, such as cycle, growth habit, and size are listed in Table 2.
Table 2. Cultivars, cycle, growth habit and architecture of the carioca beans used in the experiment.
Cultivar Cycle Growth habit Architecture IAC Imperador 70−75 d Determinate Erect IPR Curió 70 d Determinate Erect ANFC9 94 d Indeterminate Semi-erect IAC Milênio 90−95 d Indeterminate Semi-erect IPR Tangará 85−90 d Determinate Erect IPR Sabiá 87 d Indeterminate Erect BRS Pérola 90 d Indeterminate Semi-erect Each experimental unit (plot) consisted of an area of 15.0 m2 (3.0 m × 5.0 m), with sowing on 11/11/2019 in 6 rows 5 m long and 0.50 m apart. The sowing density of the bean cultivars was 14 seeds per linear meter or approximately 280,000 seeds ha−1.
The base fertilizer used was 387 kg ha−1 of formula 08-20-20 (N-P2O5-K2O) and 60 kg ha−1 of nitrogen in the form of urea (45% de N – 133 kg ha−1) when the bean cultivars were at the V3 stage, according to the chemical analysis of the soil and the expected grain yield of the crop[29].
Weed density was determined from the seed bank in the soil by applying the herbicide fluazifop-p-butyl (187.5 g ha−1) when the crop had three clovers and the weeds were between four leaves and one pollen. This timing was chosen because it is most suitable for post-emergence herbicide application. The alexandergrass weeds were protected with plastic cups to avoid injury from the herbicide. The remaining weeds in the untested experimental units were controlled by weeding. All other necessary management practices were carried out following the recommendations for the crop.
Variables analyzed
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The quantification of plant density (PD), leaf area (LA), soil cover (SC) and shoot dry matter (DM) of alexandergrass was carried out 35 days after emergence (DAE). To determine the PD, the plants were counted in two plots of 0.25 m2 (0.5 m × 0.5 m) per experimental unit. Alexandergrass soil cover was assessed visually and individually by two evaluators using a percentage scale, with a score of zero corresponding to absence of SC and a score of 100 corresponding to complete soil cover. Quantification of LA of the competing plant was performed using a portable electronic LA integrator (model CI-203, CID Bio-Science, Camas, WA, USA), with all plants measured at 0.25 m−2 per plot. After LA determination, the plants were packed in kraft paper bags and placed in a forced air circulation oven at a temperature of 60 ± 5 °C until a constant mass was reached to determine the DM of the alexandergrass plants (g m−2).
Statistical analysis
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To quantify the productivity of bean grains, the plants were harvested from a usable area of 6.0 m2 of each experimental unit when the moisture content was about 18%. After weighing the grains, their moisture content was determined and the weights were standardized to a content of 13%. Using the grain productivity data, the percentage losses compared to the plots without infestation (controls) were calculated using Eqn (1):
$\rm Loss \;({\text{%}}) = \left( \begin{gathered} \\ \\ \end{gathered} \right.\dfrac{{{\text{Ra}} - {\text{Rb}}}}{{{\text{Ra}}}}\left. \begin{gathered} \\ \\ \end{gathered} \right)\times 100 $ (1) where, Ra and Rb: crop productivity without or with the presence of, alexandergrass, respectively.
Before data analysis, the values for SC (%), LA (cm2) or DM (g m−2) were multiplied by 100, eliminating the use of the correction factor in the model[11,19,28].
The relationships between bean productivity loss percentages as a function of the explanatory variables were calculated separately for each cultivar, using the nonlinear regression model proposed by Cousens[30], derived from the rectangular hyperbolic shown in Eqn (2):
$\rm PL = \dfrac{{({\text{i}}\times{\text{X}})}}{{\left(1 + \left(\dfrac{{\text{i}}}{{\text{a}}}\right)\times{\text{X}}\right)}} $ (2) where, PL = productivity loss (%); X = plant density, soil cover, leaf area, or shoot dry matter of alexandergrass plants; i and a = productivity losses (%) per unit of alexandergrass plants when the value of the variables tends to zero and infinity, respectively. For the calculation procedure, the Gauss-Newton method was used, which estimates by successive interactions the values of the parameters for which the sum of the squares of the deviations of the observations are minimal as far as the fitted values are concerned[19]. The acceptance criterion for fitting the model to the data was based on the significance of the F-test (p ≤ 0.05), the highest value of the coefficient of determination (R2) and the lowest value of the mean square of the residuals (MSR).
The estimates of the parameter i from Equation[30] and the equation according to Lindquist & Kropff[31] (Eqn 3) were used to calculate the economic damage level (EDL):
$\rm EDL = \dfrac{{({\text{Cc}})}}{{\left({\rm R}\times {\rm P}\times\left(\dfrac{{\text{i}}}{{{\text{100}}}}\right)\times\left(\dfrac{{\text{H}}}{{{\text{100}}}}\right)\right)}} $ (3) where, EDL = economic damage level (plants m−2); Cc = control cost (herbicide and tractor-assisted soil application, in US dollars ha−1); R = bean grain productivity (kg ha−1); P = bean price (dollars kg−1 grains); i = loss of productivity (%) of carioca-type beans per unit of competing plants when plant density approaches zero, and H = herbicide efficiency (%).
For the variables Cc, R, P, and H (Eqn 3), three values occurring in the last 10 years were estimated. Thus, the average price (US
21.90 ha−1) was considered for the control costs (Cc), with the maximum and minimum costs changing by 25% in relation to the average costs. Bean grain productivity (R) was based on the lowest, average (1,672 kg ha−1) and highest value obtained in the last 10 years in Brazil[1]. Product price (P) was estimated based on the lowest, average (US${\$} $ 26.60) and highest price paid for carioca beans per 60 kg bag in the last 10 years. Herbicide efficacy (H) values were set at 80%, 90% and 100%, with 80% considered the minimum for effective weed control[32].${\$} $ -
The data that support the findings of this study are available from the corresponding author (Galon L) upon reasonable request.
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About this article
Cite this article
Galon L, Favretto EL, Cavaletti DC, Henz Neto OD, Amarante Ld, et al. 2024. Interference and economic damage level of alexandergrass on carioca type beans. Technology in Agronomy 4: e022 doi: 10.48130/tia-0024-0020
Interference and economic damage level of alexandergrass on carioca type beans
- Received: 27 December 2023
- Revised: 27 May 2024
- Accepted: 29 May 2024
- Published online: 12 August 2024
Abstract: Determining the competitive ability of bean cultivars and the economic damage level (EDL) caused by alexandergrass is important for the implementation of integrated weed management. This work aimed to evaluate the interference of alexandergrass and determine the level of economic damage when it competes with seven carioca-type bean cultivars. The experiment was conducted in a completely randomized experimental design, with treatments consisting of the carioca bean varieties IAC Imperador, IPR Curió, ANFC9, IAC Milênio, IPR Tangará, IPR Sabiá, and BRS Pérola and 12 alexandergrass densities for each cultivar, ranging from 0 to 560 plants m−2. Plant density, leaf area, soil cover, and shoot dry matter of alexandergrass were evaluated 35 d after emergence. The variables alexandergrass plant density, grain productivity, control costs, bean price, and herbicide efficiency were used to estimate EDL. The cultivars ANFC9, IAC Milênio, and IPR Tangará were the most competitive, and IAC Imperador, IPR Curió, IPR Sabiá, and BRS Pérola the least competitive against alexandergrass. The highest EDL values were observed in the cultivars ANFC9, IAC Milênio and IPR Tangará, which ranged between 3.80 and 15.70 plants m−2 of alexandergrass. The cultivars IAC Imperador, IPR Curió, IPR Sabiá, and BRS Pérola showed the lowest economic damage with 1.10 to 5.60 plants m−2 of alexandergrass.
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Key words:
- Phaseolus vulgaris /
- Urochloa plantaginea /
- Competitive interaction