Faba Bean ( Vicia faba L.) Variety Evaluation for Disease Resistance, Yield, and Agronomic Traits in South Gondar, Ethiopia

. A feld study was conducted to evaluate faba bean varieties for yield and yield components and disease reactions in the Lay Gayint district during the 2020 and 2021 cropping seasons. Six faba bean varieties, including local, were arranged in a randomized complete block design with three replications. Te crop and disease data were collected, and the disease severity was assessed fve times in 7 and 10days intervals using the disease rating scale for chocolate spot and faba bean gall disease, respectively. Te combined analysis variance showed signifcant ( P < 0 . 01 ) diferences among faba bean varieties in agronomic traits, disease severity, and area under the disease progress curve. Te variety Numan had a higher chocolate spot (46.52%) and faba bean gall (40.46%) disease severity. Te area under the disease progress curve (AUDPC) of the chocolate spot was higher on local (1292.85%-days). For faba bean gall, a higher AUDPC value (994.08%-days) was calculated from the Numan variety. Te lowest severity of chocolate spot (27.37%) and faba bean gall (21.02%) was assessed from the variety Gora, and this variety also had the lowest chocolate spot AUDPC. Te variety Gora and Ashebeka provided the highest grain yield (21988kg · ha − 1 ) and (20624 kg · ha − 1 ), respectively. Te results of the correlation analysis also indicated that the highest yield was associated with lower disease occurrence. In conclusion, varieties Gora and Ashebeka are found to be moderately resistant varieties to chocolate spot and faba bean gall disease than other varieties with higher yields, and these varieties are recommended for production in the study area and other similar ecologies.


Introduction
Legume crops are essential components of the diverse farming systems of the world.In Ethiopia, legume crops occupied 12.90% (1,674,950.34hectares) of the grain crop area and 9.36% (3,199,998.865tons) of the grain crop production [1].From the same source, it is explained that faba beans, common beans, chickpeas, and feld peas covered 3.89% (504,569.99hectares), 2.4% (311,583.58hectares), 1.7% (220,719.2hectares), and 1.69% (219,927.59hectares) of the grain crop area and 3.13% (1,070,636.538tons), 1.61% (552,564.074tons), 1.33% (457,319.37tons), and 1.10% (376,236.883tons) of the grain production, respectively.Faba bean (Vicia faba L.) is an annual herbaceous crop that belongs to the family Fabaceae with a diploid chromosome number of 2n � 12.It covers roughly 2.6 million hectares globally and is also known as broad bean, horse bean, and occasionally feld bean [2].Ethiopia is the world's second-largest producer of faba beans, after China [3,4].According to the CSA [5], the faba bean makes up around 29.9% of the yearly production of pulses and is the main source of protein for Ethiopians living in rural areas [6,7].As a potential rotational crop that improves soil fertility through nitrogen fxation, it makes a signifcant contribution to soil fertility [3,8].It is an excellent protein complement to cereals and other starchy root and tuber foods in human nutrition due to its high lysine and tryptophan content [9].While its dried seeds, green haulm, and dry straw are utilized as animal feed, it also produces items that are a high-quality source of protein for human use [10].
Te crop was widely cultivated in prospective mid-and high-altitude regions of the nation, with elevations ranging from 1800 to 3000 meters above sea level, according to [11].Te Arsi and Bale Highlands, the Central highlands of Ethiopia (Southwest, West, and North Shewa), Tigray, North and South Wollo, North and South Gondar, the East and West parts of Gojjam, Wollega, the Guji highlands, Hadiya, Sidama, and Gamo-Gofa are just a few eco-geographical regions where it can be found growing.It was one of the best-performing crops under global warming and climate change, according to [12], because of its exceptional capacity to thrive in the majority of climatic conditions and extensive adaptability to a variety of soil settings.
Despite its wider area and agroecology coverage as well as its diverse importance as food, animal feed, improving soil fertility, and foreign currency earnings, the productivity of faba bean in Ethiopia is far below (1.912 t•ha −1 ) the crop's average potential (more than 5 t•ha −1 ).Among the major barriers to faba bean production in Ethiopia, the lack of access to improved and high-yielding varieties (in spite of the release of a large number of improved varieties) and the impact of various forms of disease-causing pathogens took the lion's share.Te South Gondar zone is among the major coolseason faba bean growing areas of the Amhara region, with no or limited access to high-yielding and disease-resistant varieties.Consequently, the farmers of the locality are forced to cultivate low-yielding and susceptible varieties.Terefore, in order to reduce the actual and potential yield diference due to limited access to improved varieties, the high-yielding varieties should be tested, introduced, and made accessible to farmers within the shortest possible period of time.
Te two main diseases afecting faba bean production in Ethiopia are faba bean gall (Olpidium viciae Kusano) and chocolate spot (Botrytis fabae Sardina), which both frequently cause a decrease in faba bean production [13].Chocolate spot is characterized by the emergence of reddishbrown spots on leaves that expand and merge, causing severe premature defoliation.Te disease severely afects faba bean production and causes yield reduction of up to 61% on susceptible cultivars in Ethiopia [14].Te yield losses in faba bean reached up to 30% due to faba bean rust, and when rust infection appeared together with chocolate spot, the yield losses increased up to 50% [15].Te faba bean gall disease causing-pathogen is primarily soilborne and survives up to 2 years in the soil with diseased plant debris [16].Te gall disease symptoms establish on faba bean leaves, stem, pod, petiole, and fower [17].At frst, diseased plant leaves showed chlorotic small gall symptoms with sunken on the opposite side, rolling up at the leaf margin and fnally, the collapse of stems in severely infected plants [11,18,19].Te faba bean gall caused yield losses of up to 100% [4].
Faba bean diseases are managed using various management systems, depending on the type of disease and climate conditions.Moderately resistant variety, late planting, and chlorothalonil or mancozeb fungicide have been recommended in Ethiopia for chocolate spot management [20,21].For faba bean gall disease, crop rotation, Bayleton fungicide spray, and seed treatments have been documented for its management [22,23].However, management of faba bean diseases using fungicides is criticized for their expensive cost and their efects on the environment and human and animal health.As a result, the use of resistant or tolerant varieties has been recommended as the most economical, safest, and environmentally friendly method of crop disease control.Tus, evaluation, identifcation, and introduction of improved and disease-resistant faba bean varieties have a paramount impact on the production and productivity of the crop in the study area and other potential agroecologies where such resistant varieties have not previously been cultivated.
Aside from the agronomic performance and disease resistance, plant breeders are also concerned about the relationship that may exist between plant characters, and the association between them is a distinguishing aspect of plant traits.Investigation of the association between plant traits is essential for the indirect selection of plant characters, particularly those that are difcult to quantify and have low heritability.Based on the foregoing justifcations, this study was carried out to evaluate the agronomic performance of improved faba bean varieties, their resistance to faba bean gall and chocolate spot disease, and the relationship between yields, yield-related traits, and disease severity in the South Gondar zone of Ethiopia.

Description of the Study Areas.
Te feld experiment was carried out in the Lay Gayint district during the 2020 and 2021 main cropping seasons.Lay Gayint is part of the South Gondar zone of Amhara region, Ethiopia, which is located 75 km from Debre Tabor, the administrative center of the South Gondar zone.Te elevation of Lay Gayint ranges from 1494 to 3991 meters above sea level [24].Geographically, it is located at a latitude and longitude of 12 °00′ 00″ N and 38 °19′ 00.00″E, respectively (https://latitude.to/articles-by-country/ et/ethiopia/301492/lay-gayint).
Te average annual rainfall in the area is 1352.2mm, with minimum and maximum temperatures of 9.8 °C and 14.3 °C, respectively.Te long-term monthly average rainfall and temperature are presented in Figure 1.Nitisol and vertisol are the major soil types of Lay Gayint.Major crops grown in the study area are faba bean, barley, feld pea, potato, wheat, oat, lentil, chickpea, tef, and root crops.Te average monthly minimum and maximum temperatures for Lay Gayint are 7.59 °C and 18.09 °C, respectively (Figure 1).Te rainy season is from June to August, with the rest of the year being dry [25].

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International Journal of Agronomy

Experimental Materials.
Five improved faba bean varieties (Table 1) were collected from Kulumssa and Holeta Agricultural Research Centers and evaluated for their agronomic performance and disease reaction.Te local variety was also collected from the farmers and used as a local check.In both cropping seasons, all the necessary agronomic management activities were undertaken.Tree rounds of plowing were carried out for land preparation, and two seeds per hill were planted with a spacing of 10 cm between plants during the onset of rainfall after the soil received the International Journal of Agronomy 3 optimum amount of soil moisture.Tinning was conducted 10 days after emergence, and two rounds of hand weeding were undertaken at the 21 st and 45 th days after planting.Te recommended amount of NPS fertilizer (100 kg•ha −1 ) was applied during sowing.

Experimental Design and
2.4.Crop Data.On a plot basis, crop information such as days to 50% fowering and days to 75% physiological maturity was recorded.Te number of pods per plant, the number of seeds per pod, and plant height were recorded from ten randomly selected plants in two middle rows.Te average number of pods per plant obtained from ten randomly selected plants from the two central rows at maturity was used to determine the number of pods per plant.A hundred-seed weight (g) was determined by manually counting 100 seeds from the bulk of threshed seeds from each plot.Te yield (g) of each plot was measured from two middle rows and converted on a hectare basis.
2.5.Disease Assessment.Te severity of faba bean gall and chocolate spot disease was assessed fve times at 10-and 7-day intervals starting the onset of disease symptoms.Te disease severity of each disease was assessed by 10 randomly tagged plants in two central rows using a disease scoring scale.Te rating scales of each disease are 0-9 for faba bean gall [18,27] and 1-9 for chocolate spot [27].Te disease severity was converted into the percentage severity index [28] using the formula: PSI � sum of numerical ratings number of plants scored x maximum score on a scale × 100.
Using the Campbell and Madden formula, the area under the disease progress curve (AUDPC) was calculated from the percent severity index [29]: where X i is the cumulative disease severity at the i th observation, t i is the time of the i th assessment, and n is the total number of observation.
2.6.Data Analysis.Te collected data for individual seasons were subjected to independent analysis of variance using R software [30].Te homogeneity of error variance from the individual analyses of variance was tested through the application of the Brown and Forsythe test, and all the measured crop and disease data were found to have homogeneous error variance.Because the error variance was homogeneous over the two growing seasons, a combined analysis of variance was performed, and the least signifcant diference was utilized to compare treatment means at a 5% probability level.Pearson's method of correlation analysis was applied to determine the character association between yield, agronomic traits, and disease intensity.2. Te pooled analysis revealed highly signifcant ((P < 0.01) diferences among varieties, years (except hundred-seed weight), and the interaction of varieties with years in yield and yield components of faba bean varieties for all assessed traits (S1 Table ).In the other study, there was a signifcant diference among the tested faba bean varieties across seasons [31][32][33][34].

Results and Discussion
In phenological data, the lowest (53 days) days to 50% fowering was recorded for varieties Ashebeka, Numan, and local, while the variety Tumsa took longer (71.83 days) days to produce fowers.In this regard, the early matured (124.5 days) variety was Ashebeka and the late (140 days) matured was the variety Tumsa.Te variety Gora had a higher (2.2) number of branches per plant than other varieties tested.In a previous study, Kindie and Nigusie [32] reported the maximum number of branches per plant on the Gora variety among other evaluated faba bean varieties.
Te plant height ranged from 90.5 cm to 105.43 cm, with a mean of 96.30 cm.Te highest (105.43 cm) plant height was recorded for the Gora variety, while the lowest (90.5 cm) was measured for the Tumsa variety.Asefa and Adare [35] recorded the highest plant height for the Gora variety.Te variety Gora had the highest (9.68) number of pods per plant and the number of seeds per pod (7.99).Varieties Tumsa and local had the lowest number of pods per plant with values of 4.75 and 4.83, respectively.Te lowest number of seeds per pod was recorded for Numan and Tumsa varieties (Table 2).In other studies, variations in the number of pods per plant and the number of seeds per pod have been reported among evaluated faba bean varieties [18,32,36].
In the present study, there was a variation among varieties in yield and yield-related traits.Te variation may be attributed due to genetic makeup of the variety, environmental Correspondingly, a signifcant (P < 0.05) variation was observed in hundred-seed weight and grain yield between tested faba bean varieties in combined analysis over years (Table 2).Te variety Tumsa had the highest 100-seed weight (111.33 g), while the variety Ashebeka had the lowest (70.67 g).A similar fnding has been reported by Yitayih and Azmeraw [18] that obtained the highest hundred-seed weight from the Tumsa variety in South Gondar, Ethiopia.Te variety Gora had the highest (21988 kg•ha −1 ) grain yield, followed by Ashebeka (20624 kg•ha −1 ), while the lowest (7012.5 kg•ha −1 ) yield was obtained from the Numan variety.Te study by Wondwosen et al. [36] reported the highest (4.4 t•ha −1 ) yield from the Gora variety in North Shewa, Ethiopia.In other studies, Gora was also reported as the highest-yielding variety among other tested varieties [34,35].In the present study, the highest number of branches per plant, number of pods per plant, number of seeds per pod, and 100-seed weight measured from the variety Gora were important traits to indicate the genetic potential of Gora in providing high yield.

Response of Faba Bean Varieties to Diseases
3.2.1.Disease Severity.Tere were highly signifcant (P < 0.01) diferences in disease severity of both diseases among faba bean varieties in combined analysis over the two years (S2 Table and Table 3).Te response of varieties to faba bean diseases such as faba bean gall and chocolate spot varied in inducing disease severity.
Among the tested faba bean varieties, the highest (46.52%) chocolate spot disease severity was assessed on Numan and Tumsa, while the lowest severity (27.37%) of this disease was recorded for the Gora variety with a mean value of 39.47% (Table 3).Te result indicated that the tested varieties responded diferently to chocolate spots (Figures 3 and 4).A previous study by Ashenaf and Mekuria [38] and Yitayih and Azmeraw [39] reported varying levels of chocolate spot disease severity among evaluated faba bean varieties in Ethiopia, which is inconsistent with the current fndings.Te varying response of improved faba bean varieties to chocolate spots suggests the necessity for evaluation and identifcation of resistant varieties to be produced in potential agroecologies.On the contrary, Sahile et al. [40] found no signifcant differences in chocolate spot resistances among the faba bean varieties, which could be due to the varieties' similar disease resistance or an unfavorable environment for the pathogen to express its disease-causing genetic potential.
Te severity of faba bean gall disease varied signifcantly among the studied faba bean varieties (Table 3).Numan had the greatest gall severity value (30.46%), whereas Gora had the lowest (21.02%) severity (Figures 3 and 4).Similarly, Wondwosen et al. [36] and Kassa et al. [34] reported the Gora variety to be moderately resistant to faba bean gall disease, with the lowest severity value, which is consistent with the results of this study.Furthermore, research fndings from across locations and over the years [18,36] revealed that the studied faba bean varieties had signifcant variations in faba bean gall disease severity.In general, the present study demonstrated that the variety Gora was a relatively resistant variety to chocolate spot and faba bean gall diseases when compared to all of the tested improved faba bean varieties.

Area under Disease Progress
Curve.Signifcant (P < 0.05) variations were observed in an area under the disease progress curve (AUDPC) of both assessed diseases among improved faba bean varieties in combined analysis over the years.Te values of AUDPC of chocolate spot and faba bean gall varied in the tested varieties (Table 3).Similar to this study, Yitayih and Azmeraw [18] and Wondwosen et al. [36] reported signifcant diferences among improved faba bean for gall disease over the years.
Yitayih and Azmeraw [39] also noted various levels of chocolate spot epidemics among varieties.In the current study, the highest (1292.85%-days)AUDPC value of chocolate spot was calculated for local cultivars, while the lowest (976.19%days)value of AUDPC was computed for the variety Gora.In another study without the variety Gora, chocolate spot-infected International Journal of Agronomy faba bean varieties in diferent levels and the variety Tumsa induced the lowest AUDPC value in South Gondar [39].In this study, early infection of faba bean varieties by gall disease was greatly difered.In this regard, the variety Numan had the highest (994.08%-days)AUDPC value, whereas Ashebeka had the lowest (791.46%),followed by Tumsa (816.01%).A previous study by Yitayih and Azmeraw [39] reported the lowest amount of AUDPC on the variety Tumsa, which is moderately resistant to gall disease, in South Gondar.Similar to the current study, Wondwosen et al. [36] noted a lower gall disease epidemic in a variety Gora in North Shewa.
Te disease progress curve indicated the duration of the disease epidemic over time and the efects of faba bean varieties on the epidemic of faba bean diseases were demonstrated (Figures 3 and 4).In this regard, the diseases appeared 57 days after planting (DAP) and progressed up to 83 DAP for chocolate spot and also appeared at 40 DAP and progressed up to 80 DAP for faba bean gall disease.Te chocolate spot progressed quickly on Numan, local, and Diba varieties compared to other varieties.However, the disease progress of chocolate spot was reduced on varieties Gora, Ashebeka, and Tumsa (Figure 5).Te disease progress of faba bean gall was increased on the variety Numan compared to other varieties, while gall disease progression was decreased on the variety Gora (Figure 6).

Association of Yield and Yield Components and Severity of
Diseases.Pearson's correlation coefcient analysis of agronomic traits and yield and disease severity is presented in Table 4. Correlation coefcient research revealed the association between essential crop variables, indicating a guiding model for direct and indirect grain yield improvement [41].Days to 50% fowering had a highly signifcant and positive relationship with a date of 75% physiological maturity (r � 0.42), as well as a substantial and low positive relationship with chocolate spot (r � 0.39).Tis fnding suggested that the severity of the chocolate spot increased as the date of maturing approached.Te date of physiological maturity at 75% showed a highly signifcant and negative relationship with hundred-seed weight (r � 0.45).
Plant height (r � 0.64), number of pods per plant (r � 0.77), and grain yield (r � 0.67) showed a highly signifcant and substantially positive relationship with the number of branches per plant.Te number of branches per plant (r � 0.82) was found to have a highly signifcant and very strong positive relationship with the number of seeds per pod.Tis means that as the number of branches increased, so did the yield.Tis fnding aligned with the fndings of Zebire and Tadesse [35] and Elshafei et al. [42], who found a signifcant and positive relationship between plant heights, number of pods per plant, number of seeds per pod, and seed yield per plant.Te number of branches per plant was found to have a highly signifcant and negative association with faba bean gall (r � 0.49).Tis    International Journal of Agronomy suggested that when disease infected faba bean, the number of branches decreased.Plant height (r � 0.86) had a highly signifcant and very strong positive association with the number of pod plants.Plant height (r � 0.67) was found to be a highly signifcant and strong positive factor in the number of seeds per pod.Plant height was found to have a highly signifcant and positive association with grain yield (r � 0.57).Plant height was highly signifcant and negatively correlated with faba bean gall disease (r � −0.76).Te number of pods per plant had a highly signifcant and strong positive relationship with the number of seeds per pod (r � 0.86) and grain yield (r � 0.76).Te number of pods per plant had a highly signifcant and negative relationship with chocolate spot (r � −0.59) and faba bean all disease(r � −0.78).
Te number of seeds per pod had a highly signifcant and strong positive association with grain yield (r � 0.898).Similarly, Elshafei et al. [42] reported a positive association between the number of pods per plant with seed per pod and grain yield.Te number of seeds per pod was highly signifcant and negatively associated with chocolate spot (r � −0.43) and faba bean gall (r � −0.57).Grain yield was highly signifcant and negatively associated with chocolate spot (r � −0.45) and faba bean gall (r � −0.359).Te present results indicated that the severities of the diseases are critical factors in determining yield and yield component loss of faba bean.In line with this result, the negative association between grain yield and faba bean gall disease has been reported [36].In other research, the severity of chocolate spot and faba bean gall was a key factor in lowering grain production [18].

Conclusion and Recommendation
Te faba bean is one of Ethiopia's most important legume crops, with enormous nutritional and economic value.Tis study's combined analysis of variance revealed signifcant variations in grain yield among the tested varieties.Gora was found to be the highest-producing variety among the studied faba bean varieties and can be recommended for cultivation in the study area.Chocolate spot and faba bean gall diseases are the most economically devastating biotic constraints that afect faba bean production anywhere, particularly in the highlands of Ethiopia.Te evaluated faba bean varieties showed signifcantly diferent levels of disease severity for chocolate spot and faba bean gall diseases.In this regard, Gora and Ashebeka produced lower disease severity with an increased amount of yield than the other tested varieties.Terefore, Gora and Ashebeka, which produced lower disease severity coupled with higher grain yield, can be considered moderately resistant varieties so that they can be used to manage the epidemic of chocolate spot and gall diseases in faba bean-growing areas.In addition to variety performance and their disease resistance ability, positively correlated plant characteristics like the number of branches per plant, plant height, number of pods per plant, and number of seeds per pod should be considered and given due attention during the selection and yield improvement program of faba bean varieties.
Fieldworks.Te study was laid out in a randomized complete block design with three replications in the Farmers Training Center.Te experimental plot was 1.4 m by 4 m, with 0.4 m between rows and 0.1 m between plants, respectively.Blocks and plots were separated by 1.5 m and 0.5 m, respectively.Each plot had four rows, the inner two rows were used for data collection, and the two outermost rows served as a border.

3. 1 .
Yield and Yield-Related Parameters.Te results of the pooled analysis over years are depicted in S1

Figure 3 :
Figure 3: Evaluation of the improved faba bean variety at Lay Gayint in the 2020 main cropping season.

Figure 4 :Figure 5 :Figure 6 :
Figure 4: Evaluation of the improved faba bean variety at Lay Gayint in the 2021 main cropping season.

Table 1 :
[37] of experimental materials studied at Lay Gayint.thevarieties'response to disease reactions.Tis fnding is consistent with the fndings of[35], which discovered Gora has the tallest (46.6 cm) plant of the evaluated varieties.Similar to Kindie and Nigusie's[32]fndings, Gora recorded the highest (46.6 cm) plant, while Tumsa revealed the longest plant height (117.40 cm).Tadele et al.[33]and Kumar et al.[37]also reported genotypic variations among tested varieties in days to fowering, plant height, number of pods per plant, and hundred-seed weight traits.

Table 2 :
Te combined mean performance of yield and yield components of faba bean varieties in the 2020 and 2021 cropping seasons.days to fowering; DM � days to maturity; NBP � number of branches per plant; NPP � number of pods per plant; NSP � number of seeds per pod; PH � plant height; HSW � hundred-seed weight; GY � grain yield.CV � coefcient of variance; LSD � least signifcance diference.Te varieties represented by "b, c, d, and e" are statistically diferent from the variety represented by "a" at 5% level of signifcance for both traits.Te variety represented by "a" has a greater value than varieties assigned "b, c, d, and e." Te same procedure is true to compare varieties represented by "b" with those represented by c, d, and e.
a DF �

Table 3 :
Te response of improved faba bean varieties to severity and AUDPC of faba bean diseases in the 2020 and 2021 cropping seasons.percent severity index; AUDPC � area under disease progress.CV � coefcient of variance; LSD � least signifcance diference at a 5% level.Te varieties represented by "b, c, d, and e" are statistically diferent from the variety represented by "a" at 5% level of signifcance for both traits.Te variety represented by "a" has a greater percent severity index and area under the disease progress curve than the other varieties, and this variety is more susceptible than the others.
a PSI �

Table 4 :
Correlation coefcients (r) between faba bean yield and yield component and severity of diseases during the 2020 and 2021 cropping seasons.