Advances in Crop Science and Technology
Open Access

Component crop; Essential oil; LER; MAI; Oleoresin

Introduction

The Ethiopian population is growing rapidly, leading to rapid urbanization and a decrease in arable land areas owned by individual crop-producing households (Mekuria, 2018). Moreover, declining land productivity and the effects of climate change have imposed variable pressure on crop production to feed this rapidly growing population. However, to meet the needs of the country, crop production needs to be increased on existing land. According to FAO (2009), approximately 90% of the growth in global crop production is expected from higher yields and increased cropping intensity, and the remaining 10% is due to the expansion of productive land. Thus, intercropping can help achieve the expected yield by effectively utilizing the available growth resources. Intercropping involves the simultaneous production of two or more companion crops on a specified unit area of land to increase land productivity by intensifying the system and reducing the risk of total crop failure. Intercropping enhances crop diversification, creates yield stability over seasons, and increases gross returns per unit area without additional input to land area (Brooker et al., 2015; Temesgen et al., 2015) [1-3].

The Sidama region, which is situated in southern Ethiopia, is known for its high population density and small landholdings at the household level. Consequently, smallholder farmers in this region often practice intercropping to meet their livelihood requirements. Hawassa City, located in the northern part of the region, has become a significant producer of vegetables and aromatic herbs and medicinal plants in both domestic and export markets. In this district, intercropping of green hot peppers with basil is a common farming technique used by small landholders, as reported by Gabiso et al. (2015) [3].

Green hot pepper is an important and widely grown crop in various regions, and is known for its green and dry pods. It is a leading cultivated vegetable crop, covering over 4.10% of the total vegetable production area, with an average productivity of 6.29 tons per hectare in the country (CSA, 2017). However, this is significantly lower than the world average of 18.57 tha-1 (FAO, 2015). Basil, on the other hand, is a medicinal and aromatic herb that has been traditionally used for various purposes in the country (Khalid, 2006) [4]. The fresh and/or dried parts of the herb are used in daily food preparations in the country (Atey, 2008), and the essential oil extract is used in the food, pharmaceutical, and cosmetic industries (Svecova & Neugebauerova, 2010). Intercropping hot peppers with other species, including basil, has been reported to improve crop yields and reduce losses caused by insect pests, diseases, and weeds (Kahn 2010). The presence of phytonutrients, such as glucosinolates, capsaicin, and sulfides, in hot peppers makes them good candidates for intercropping with basil to improve the main crop yield (Mutisya et al., 2016) [5].

However, smallholder farmers in the district surrounding Hawassa cultivate basil within green hot peppers without a defined plant density per unit area. In addition, there is currently a lack of scientific information regarding the benefits of intercropping these crops in this area. Therefore, this study aimed to determine the optimal basil density for intercropping with green hot pepper varieties in Hawassa district, and to assess the impact of intercropping on the yield and economic returns of both crops in the study area [6].

Materials and Methods

Study area description

The experiment was conducted under field conditions in Hawassa Green Mark Herbs, P.L.C., Southern Ethiopia. The area is located within the great rift valley in the Sidama region of Hawassa city surrounding the district (7o 05’ N and 39o29’E; 1652 meter above sea level), 270 km away from the capital city (Kassahun et al., 2014). It receives minimum and maximum mean annual temperatures of 12.94 0C and 27.34 0C, respectively. The area also receives minimum and maximum mean annual rainfall of 1000-1800 mm. The soil in the area was dominated by a sandy clay loam texture and was classified as an andosol with a pH of 7.84 [7].

Experimental materials and used design

Two green hot pepper varieties (Melka Shote and Melka Awaze) obtained from the Melkassa Agricultural Research Center (MARC) and one basil variety (Won.06) obtained from the Wondo Genet Agricultural Research Center (WGARC) were used as the experimental materials. Green hot pepper is considered the main crop, whereas basil is considered a companion crop. Two green hot pepper varieties and four basil population densities (100% [55,556 plants ha^-1], 75% [41,667 plants ha^-1], 50% [27,778 plants ha^-1], and 25% [13,889 plants ha^-1]) with their soles as a control were laid out in a randomized complete block design (RCBD) with three replications [8]. The experiment had a total area of 499.5 m2 (13.5 m width and 37 m length) with a plot area of 8.4 m2 (3.5 m width and 2.4 m length). The spacing between blocks and plots was maintained at 1.5 m and 1 m, respectively. Each plot consisted of five rows for the green hot pepper variety, and six rows for the basil variety. The recommended spacing for basil is 60 × 30 cm (Egata et al., 2017) and 70 × 30 cm for green hot pepper (EARO, 2004). Following the field establishment of the experiment, the recommended field management practices (weeding, cultivation, and fertilizer application) were uniformly applied to all the treatments [9,10].

Collected data

Data for green hot pepper varieties were collected from six randomly selected plants in the central row of each plot, as follows:

Phenology and growth parameters

Plant height (cm): Height measurements were obtained from six plants using a measuring tape (model no. of Tape Measure-6201 and reading scale of 5m) from the base to the tip of the main stem when 50% of the first fruit began to mature. Mean plant height was calculated by dividing the total sum by the number of sampled plants [11].

Days to 50% flowering: The number of days taken from transplantation to 50% of the plants producing at least one open flower was measured in each plot, with six plants sampled from each plot. The total sum was divided by the number of sampled plants to calculate the mean number of days to 50% flowering per plant.

Days to 50% fruit maturity. The mean number of days taken for 50% of the fruit to reach physiological maturity was calculated by counting the number of days of fruit maturity for the six plants sampled from the plots and dividing the sum by the number of plants.

Number of primary branches per plant: Primary branches of randomly selected plants were tallied at the time of harvest. To determine the mean number of primary branches, the total number of branches was divided by the number of sampled plants [12,13].

Canopy diameter (cm): Canopy coverage was assessed for six randomly chosen plants and measured using a measuring tape (model no. Tape Measure-6201 with a reading scale of 5m) by determining the distance from the widest point at one corner to the other in both the north–south and east–west directions before harvest. Measurements were taken in centimeters, and the average canopy diameter was calculated by dividing the total sum by the number of plants sampled.

Fruit number per plant: The average number of fruits per plant was determined by calculating the total sum and dividing it by the number of randomly selected plants that had reached physiological maturity, which was characterized by fruit firmness before turning red.

Fruit length (cm): Fruit length was measured from the base of the fruit to its tipping point using a digital caliper (Model No. 4141 with a reading scale of 0-30 cm) immediately after harvesting. Measurements were taken for six randomly selected plants and the average fruit length was obtained by dividing the total sum by the number of sampled plants.

Fruit diameter (cm): The diameter of green fruits was measured for six plants using a digital caliper (Model No. 4141 with a reading scale of 0-30 cm) at the central points of each fruit immediately after harvest, and the results were expressed in centimeters. Mean fruit diameter was calculated by dividing the total sum by the number of sampled fruits [14,15].

Total marketable fresh fruit yield (t ha^-1): Six plants were randomly selected and marketable green fruits were harvested and weighed using a sensitive balance (Model No. yt-1002, with a reading scale of 0.01) before turning red. The weight was expressed in grams. The mean marketable fruit yield was calculated by dividing the total weight by the number of sampled plants and was converted to tons per hectare.

Oleoresin content (%): Oleoresin was extracted from green hot peppers using dried pods as the sample. The solvent extraction method was employed, with a composite sample of ground dry fruit weighing 70 g charged into a Soxhlet apparatus along with acetone solvent. The sample was left for extraction for 4 h before the non-volatile components were dissolved in acetone. The desired compound was then collected in a distillation flask and the oleoresin content was determined by evaporating the solvent. The results were expressed as percentages (% w/w) based on the dry weight of the sample [16,17].

Basil data were collected from six randomly selected plants in the central row of each plot.

Growth parameters

Number of primary branches per plant: Primary branches of randomly selected plants were tallied at the time of harvest. To determine the mean number of primary branches, the total number of branches was divided by the number of sampled plants.

Canopy diameter (cm): Canopy coverage was assessed for six randomly chosen plants and measured using a measuring tape (model no. Tape Measure-6201 with a reading scale of 5m) by determining the distance from the widest point at one corner to the other in both the north–south and east–west directions before harvest. Measurements were taken in centimeters, and the average canopy diameter was calculated by dividing the total sum by the number of plants sampled [18,19].

Yield attributes and yield parameters

Fresh herb yield (tha^-1) Fresh herbs were harvested from six randomly selected plants and weighed using a sensitive balance (model no. yt-1002 with a reading scale of 0.01 g) immediately after the leaves were separated from the stem, and expressed in grams. The mean fresh leaf yield per plant was calculated by dividing the total weight by the number of sampled plants and was converted to tons per hectare.

Dry herb yield (tha^-1): The dry weight of the herb per plant was determined by taking 100 g from a selection of plants and drying them in an oven at 100 °C until they reached constant weight. Dried samples were weighed using a sensitive balance (Model No. yt-1002, with a reading scale of 0.01 g), and expressed in grams. The mean dry leaf yield was calculated by dividing the total weight by the number of sampled plants, and converting the results to tons per hectare [20].

Essential oil content (%): The essential oil content was obtained through hydro distillation, using the procedure described by Bisrat et al. (2009). The dried basil herb was placed in a round-bottom flask and subjected to hydro distillation in a Clevenger apparatus. The harvested plants were separated into leaf and stem parts, and composite samples of dry herbs with a biomass of 300 g were placed in a Clevenger apparatus with 700 ml of water and trapped for three hours (Guenther, 1972). Water was poured into the flasks until the plant samples were completely submerged [21, 22]. The round-bottom flask was placed on a heated mantle and the water with the plant sample was allowed to boil for three hours. Essential oil was collected and measured using a pipette. Essential oil content was determined using the following formula (Rao et al. 2005);

Essential oil yield (kg ha^-1): The oil collected in the tube of the apparatus was subjected to dehydration, weighed, and expressed on a dry-weight basis (% w/w). The essential oil yield per hectare was calculated using the following formula (Badawy et al. 2009):

Intercropping indices

Land equivalent ratios (LER)

The yield advantage indices of intercropping of both crops were calculated using the land equivalent ratio (LER), according to Willey (1979) and Onwueme et al. (1991).

Where; Yin=Yield in intercropping, Ys =Yield in sole crop

Monetary advantage index (MAI)

The economic advantage indices of intercropping of both crops were calculated using the Monetary Advantage Index (MAI) according to Ghosh (2004).

Note: LER greater than one and higher and positive MAI were considered yield advantage and economic benefits of intercropping for both crop components in the study area, respectively. Hence, the value of the combined intercrops in each cropping system was the lowest prevailing market price per kilogram for each component crop in Ethiopian Birr (ETB) at the time of the experiment. The prices of green hot paper and basil herbs were obtained from the Hawassa vegetable and herb market at the time of harvest in the first week of January, 2018. Accordingly, the prices of green hot pepper and basil leaves were 56 ETB kg^-1 (~ 2 USD) and 27 ETB kg^-1 (~ 1 USD), respectively. (1USD = 27.20 ETB).

Data analysis

Data collected on growth, yield, and quality parameters were subjected to two-way analysis of variance (ANOVA) to test the significant effects of the two factors (green hot pepper variety and basil population density) and their interaction effects. The pooled data of population densities with their individual cropping systems were also compared to test the significant effects of the cropping system on the growth, yield components, and yields of the two crops separately. The calculated land equivalent ratio (LER) and monetary advantage index (MAI) were also subjected to two-way analysis of variance using the General Linear Model (GLM) of the Statistical Analysis System (SAS) software version 9.3. Duncan's Multiple Range Test (DMRT) at 5% probability was used for mean separation when analysis of variance indicated the presence of significant differences. In addition, linear regression model was used to indicate the relationship between treatments with interacted parameters [23-25].

Results

Effect of intercropping on phenology, growth, yield attributes and yield parameters of green hot pepper

Analysis of variance revealed that, except for oleoresin content, all other parameters showed non-significant interaction effects between varieties, population density, and pooled mean of cropping systems (P > 0.05). The number of days to 50% flowering, plant height, primary branch number per plant, canopy spreading, and fruit number per plant of green hot pepper were significantly affected by variety (P≤0.05) and population density (P≤0.05), respectively [26]. In addition, the marketable fresh fruit yield per hectare was significantly affected by population density but not by variety. Furthermore, days to fruit maturity were significantly affected by variety (P≤0.05) but not by population density. Thus, the Melka Shote variety had a later 50% flowering day, taller plant height, higher primary branch number per plant, earlier matured fruits, higher fruit number per plant, and narrower canopy spread than did the Melka Awaze variety. On the other hand, the earliest days to 50% flowering, the greatest plant height, widest canopy spreading, maximum primary branch number per plant, maximum fruit number per plant, and maximum marketable fresh fruit yield (8.05 tha^-1) were obtained when the green hot pepper varieties were intercropped with the lowest density of basil (25%) (Table 1 and Table 2) [28,29].

Table 1: Means for phenology and growth parameters of green hot pepper as affected by varieties, population density and cropping systems in Hawassa

Table 2: Means for yield components and yield of green hot pepper as affected by varieties, Population density and cropping systems in Hawassa

The cropping system exerted a significant effect (P≤0.05) on plant height, primary branch number per plant, canopy spread, days to fruit maturity, and marketable fresh fruit yield per hectare but not on days to 50% flowering. As a result, the sole cropping system led to a taller plant, more primary branches per plant, a wider canopy spread, earlier fruit maturity, and a higher marketable fresh fruit yield (8.58 tha^-1) compared to the intercropped system. However, the intercropping of basil at different population densities within green hot pepper varieties reduced the marketable fruit yield per hectare by 23% compared to the sole cropping system [30].

The oleoresin content of green hot peppers was significantly influenced by the interaction of both main effects (Figure 1) and cropping systems (p≤0.05). Therefore, it can be observed that the Melka Shote variety, when intercropped with a basil population density of 50%, exhibited the highest percentage of oleoresin content (8.59%) compared to the other treatments. Conversely, the combination of the Melka Awaze variety intercropped with the maximum basil population density (100%) resulted in the lowest oleoresin content (3.69%). Through regression analysis, it was determined that the average oleoresin content of the Melka Awaze variety, when intercropped with a basil density of 100%, was 4.89% lower than that of the Melka Shote variety intercropped with a basil density of 50%, while keeping all other factors constant. However, a higher percentage of oleoresin was recorded when basil was intercropped with green hot pepper varieties than with the sole cropping system (Figure 1 and Figure 2) (Table 3).

Figure 1: Interaction of green hot pepper varieties with different population densities of basil for oleoresin content of green hot pepper fruits in Hawassa. Bars capped with the same letter/s are not significantly different (P>0.05). CR and CV indicate critical ranges and coefficient of variation, respectively.

Figure 2: Pooled mean oleoresin content of intercropped and sole green hot pepper varieties in Hawassa. Bars capped with the same letter/s are not significantly different (P>0.05). CR and CV represent the critical ranges and coefficients of variation, respectively.

Table 3: Linear regression of oleoresin content in percentage with interaction values of green hot pepper varieties intercropped with population density of basil.

Effect of intercropping on growth, yield components and yield parameters of basil

Similar to green hot pepper, basil yielded different results for growth, yield components, and yield parameters for the interaction of two main factors: green hot pepper varieties, population densities, and pooled mean of cropping systems. According to the analysis of variance, the population density of basil intercropped with green hot pepper significantly (P≤0.05) influenced the primary branch number per plant, fresh and dry herbage yield per hectare, essential oil content, and essential oil yield per hectare of basil. In addition, intercropping basil with both green hot pepper varieties significantly (P≤0.05) affected only fresh herbage yield per hectare. Therefore, the highest number of primary branches per plant, the lowest fresh (2.75 tha^-1) and dry herbage yield (0.42 tha^-1), essential oil content, and essential oil yield (3.60 tha^-1) per hectare were recorded from the lowest population density of basil [31].

In addition, the intercropping system of basil significantly (P≤0.05) affected the fresh herbage yield (6.01 tha^-1), dry herbage yield (0.92 tha^-1), and essential oil yield (10.35 kg ha^-1) compared with its sole cropping counterpart. Thus, the basil fresh herbage yield per hectare was reduced by 50.21% when intercropped with green hot pepper varieties compared with sole cropping [32].

The interaction effects between the different varieties of green hot pepper and the density of basil had a significant impact on the spread of the basil canopy (P≤0.05). As a result, the widest canopy spread (39.33 cm) was observed when intercropping the Melka Awaze variety with a basil population density of 75%, whereas the narrowest canopy (33.16 cm) was obtained when using a density of 100% for both varieties. By conducting regression analysis, it was determined that the average canopy spread of the Melka Awaze variety, when intercropped with a basil density of 100%, was 6.167cm narrower compared to when intercropped with a basil density of 75%, while all other factors remained constant (Figure 3) (Table 4 and Table 5).

Figure 3: Interaction of hot pepper varieties with different population densities of basil on canopy spread of basil in Hawassa. The bars capped with the same letter/s were not significantly different (P>0.05). CR and CV indicate Critical Ranges and Coefficient of Variation, respectively.

Table 4: Mean values for growth, yield, and quality of basil intercropped with hot pepper as affected by hot pepper varieties, population densities of basil, and cropping system in Hawassa

Table 5: Linear regression of Canopy Spreading (CS) interaction values of basil population densities intercropped with green hot pepper varieties.

Productivity indices of intercropping system

Total land equivalent ratio (TLER)

The combined effect of the variety of green hot pepper and the density of basil population had a significant impact on the overall value of total land equivalent ratio (TLER) (P≤0.05). The TLER values for intercropping green hot peppers with basil exceeded 1 for all population densities and for both varieties of green hot pepper. Specifically, a higher total TLER value was observed for intercropping both varieties of green hot pepper at all basil population densities except for 100% population densities. However, the TLER values for intercropping both varieties of green hot pepper with 100% basil population density were lower than those for the other population densities. Consequently, regression analysis revealed that the total land equivalent ratio of the Melka Shote variety, when intercropped with a basil density of 100%, was 0.56 lower than that of the Melka Awaze variety, intercropped with a basil density of 50%, while holding all other factors constant (Figure 4) (Table 6) [33].

Figure 4: Interaction between hot pepper varieties and different basil population densities for the TLER. The bars capped with the same letter/s were not significantly different (P>0.05). CR and CV indicate Critical Range and Coefficient of Variation, respectively.

Table 6: Linear regression of Total Land Equivalent Ratio (TLER) for interaction values of green hot pepper varieties intercropped with basil population density.

Monitory advantage index (MAI)

The interaction between the population density of basil and the green hot pepper variety had a significant (P≤0.05) impact on the monetary advantage index (MAI). Intercropping the green hot pepper varieties with all population densities of basil (apart from 100%) produced the highest positive MAI value. However, when the variety Melka Shote was grown with a 100% population density of basil, the lowest value of 111,475 ETB ha^-1 was recorded. Regression analysis was used to find that, when all other variables were held constant, the monetary advantage index of the Melka Shote variety intercropped with a basil density of 100% was 140050.24 ETB lower than that of the Melka Awaze variety intercropped with a basil density of 50% (Figure 5) (Table 7).

Figure 5: Interaction of intercropping hot pepper with different population densities of basil on MAI in Hawassa. The bars capped with the same letter/s were not significantly different (P>0.05). CR, CV and MAI indicate critical range, coefficient of variations, and Monitory Advantage Index, respectively.

Table 7: Linear regression of Monetary Advantage Index (MAI) with interaction values of green hot pepper varieties intercropped with population density of basil.

Discussions

The intercropping of different basil densities with in varieties of green hot peppers in the study area influenced the growth, yield attributes, yield, and intercropping indices of both crops. The response variables showed greater variability among the green hot pepper varieties, which could be due to genetic differences and the effects of plant populations per unit area (Rezaei-Chianeh et al. 2011). Variations in growth and yield parameters owing to genetic variation between hot pepper varieties have been reported in several studies (Desalegn, 2011; Haileslassie et al., 2015; Melese and Gebrselassie, 2015; Mends-Cole, 2015). In addition, the high population density of basil significantly affected the growth and yield attributes of the green hot pepper varieties, resulting in the lowest average fruit yield. This was because intercropping at the highest basil density affected light distribution in the pepper canopy, which is the most important factor affecting photosynthesis and reducing crop yield. Hence, the degree of shading and amount of light absorbed by plants can vary with plant density, contributing to yield reduction. According to Kumar et al. (2013), shade is primarily caused by densely planted crops, resulting in excessive vegetative growth that limits a crop's photosynthetic capabilities and negatively affects productivity over time. Thus, mutual shading effects promote vertical growth more than lateral shading effects do (Xiao et al., 2006). However, green hot pepper varieties intercropped with lower population densities of basil have wider canopy structures, resulting in increased interception and absorption capacity of solar radiation to enhance photo assimilation partition and biomass accumulation to the sink (Maddonni et al., 2001; Quartey et al., 2014). Crop yield is a function of the radiation intercepted over the growing season, efficiency of converting the intercepted radiation into biomass, and partitioning efficiency of biomass to fruit yield.

In addition, the sole cropping system of green hot pepper varieties outperformed the intercropped system in terms of growth, yield attributes, and fruit yield. Thus, the intercropped pepper system invested more energy in main stem elongation than in bearing lateral productive branches to compete for solar radiation interception at higher densities (Maddonni et al., 2001). Ren et al., (2017) indicated, the planting pattern in intercropped systems can influence the physiological characteristics (such as the amount of light interception and radiation-use efficiency) of the crop.

The maximum basil fresh and dry herbage and essential oil yields were obtained from the highest population (100%) compared to the lowest densities of basil. This is because a higher number of basil populations was available per unit area than at the lowest density. In addition, the maximum essential oil yield obtained was due to the multiplicity of oil extracted from the basil herbage yield harvested from the highest density per unit area. According to Chang (2005), physiological and/or biochemical changes in plants at higher population densities also influence the essential oil content, either directly through key enzyme pathways or indirectly by altering biomass allocation to the oil-producing part of the plant. Alemu et al. (2018) reported that basil herbage yield was determined by the number of plant populations per unit area.

The total LER value of intercropped green hot peppers with different basil population densities was greater than unity, implying that the growth of both crops together has a yield advantage over their solitary system. These values were complementary to the component crops for their efficient utilization of growth resources compared with their sole system (Mousavi and Eskandari,2011). Kebebew et al. (2014) reported similar LER results of greater than unity for all population densities for soyabean with maize intercropping system. Thus, higher yield advantages are obtained when competition between two species in the mixture is lower than the competition within the same species (Ghosh, 2004). Moreover, the results of these studies imply that intercropping hot pepper varieties with different basil population densities would bring about more yield advantages than their sole cropping systems, especially for small landholder producers in the targeted area. In line with this study, Kabura et al. (2008) reported a yield advantage for intercropping hot peppers with onions over their soles. Therefore, this study will help researchers uncover the critical areas of crop production through intercropping in similar areas [34]. This study presents new findings regarding the production of green hot peppers associated with basil through intercropping in the study area.

Conclusions

The purpose of this study was to identify the optimal basil density for intercropping various green hot pepper varieties in Hawassa, Ethiopia. This study revealed that intercropping had a significant influence on the growth, yield attributes, and overall yield of both crops. Compared to traditional sole cropping methods, the intercropping system showed both yield and economic advantages, with a land equivalent ratio (LER) greater than one and a monetary advantage index (MAI) that was higher and had a positive return. As a result, the study recommended basil densities for intercropping with different green hot pepper varieties. Specifically, a density of 27,778 plants per hectare was recommended for the Melka Awaze variety, and 41,667 plants per hectare for the Melka Shote variety. By following these recommendations, smallholder farmers in this area can maximize their land productivity and economic gains. In order to further enhance our understanding of the cultivation of both crops and their potential, it is advisable to conduct additional experiments in various settings and locations, particularly with regards to the dry pod and oleoresin yields of hot pepper. As this study is the first endeavor in this particular field, future research will provide valuable insights.

Significance statement

This study aimed to investigate the potential benefits of intercropping two varieties of green hot peppers and one variety of basil to smallholder farmers in the study area. The results of this study can provide insight into the critical aspects of crop production through intercropping in similar environments and will contribute to the development of new knowledge on the production of green hot peppers in combination with basil through intercropping.

Acknowledgment

We would like to express our gratitude to the Ethiopian Institute of Agricultural Research (EIAR), Wondo Genet Agricultural Research Centre (WGARC), for facilitating our field experiments and laboratory work and providing us with basil seeds. We would also like to extend our appreciation to Hawassa Green Mark Herb P.L.C management staff for their cooperation in granting us access to their nursery site and experimental field and to provide us with the necessary resources for our activity. Lastly, we extend our sincere thanks to the EIAR, Melkassa Agricultural Research Centre (MARC), for providing us with the seed of green hot pepper varieties, Mr. Melkamu Tilaye and Mr. Guta Bukaro for supporting us the regression analysis methods of the variables and to all the staff members of WGARC for their invaluable support in various aspects that enabled us to successfully carry out our activities.

Author’s contribution

Habtamu Gudisa Megersa proposed the idea, designed, executed the experiment, analyzed data, and prepared the draft of the paper. Weyessa Garedew contributed to the design of the experiment, analyzed data, and drafted and edited the paper, while also supervising the work. Belstie Lulie designed the experiment, edited and reviewed the manuscript, and provided supervision.

Data access statement

The authors confirm that the data supporting the findings of this study are available within the article.

Funding

No funding was received work

Disclosure statement

The authors report there are no competing interests to declare.

Data access statement

The authors confirm that the data supporting the findings of this study are available within the article.

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