Evaluation of Chickpea Varieties and Fungicides for the Management of Chickpea Fusarium Wilt Disease ( Fusarium oxysporum f . sp . ciceris ) at Adet Sick Plot in Northwest Ethiopia

A 2-year experiment was conducted at wilt sick plot infested with natural occurring Fusarium oxysporum f.sp. ciceris at Adet Agricultural Research Center in northwestern Ethiopia with an aim to evaluate effective chickpea varieties and fungicides for the management of chickpea fusarium wilt in order to integrate chickpea varieties and fungicides. Four varieties, namely, Shasho, Arerti, Marye, and local, two fungicides, namely, Apron Star andmancozeb, and untreated local chickpea were used as treatments. Treatments were arranged in a factorial combination in randomized complete block design in three replications. (ere were significant differences at p< 0.05 in the overall mean of fusarium wilt disease incidence, area under disease progress curve %-day, yield and yield components among varieties and fungicides treatments. Data were analyzed using SAS system version 9.2. (e results indicated that the maximum disease incidence and area under disease progress curve values 65.62% and 578.5%-day, respectively, were recorded from untreated local chickpea, while the minimum disease incidence and area under disease progress curve values 23.41% and 147%-day, respectively, were recorded from Shasho variety treated with Apron Star. (e maximum biomass and grain yield of 6.71 t/ha and 4.6 t/ha, respectively, were recorded from Shasho variety treated with Apron Star while the minimum biomass and grain yield of 0.62 t/ha and 0.21 t/ha, respectively, were recorded from untreated local chickpea. (us, the experiment results suggested that the variety of Shasho treated with fungicide Apron Star caused significant reduction in chickpea fusarium wilt incidence leading to a corresponding increase in grain yield of chickpea.


Introduction
e average productivity of chickpea in Ethiopia is much lower than the world's average and is also lower as compared to other chickpea-growing countries such as Egypt and Turkey [1]. is low productivity is mainly due to a number of biotic and a biotic stresses.Among the biotic stresses, fusarium wilt, ascochyta blight, pod borer, and cutworm and abiotic stresses, drought, heat, soil salinity, low soil fertility, and poor crop management practices are the most important limiting factors in crop production [2].However, fusarium wilt, caused by Fusarium oxysporum f.sp.ciceris, is one of the most important biotic stresses of chickpea (Cicer arietinum L.), and the average annual yield losses due to wilt have been estimated to 10 to 90% and sometimes escalate to 100% when the relative humidity is greater than 60% and temperature ranges between 10 and 25 °C [3].
e disease is prevalent in the Indian subcontinent, Ethiopia, Mexico, Spain, Tunisia, Turkey, and the United States [4].Fusarium oxysporum f.sp.ciceris is a vascular pathogen that perpetuates in seed and soil and hence is difficult to manage by the use of single control method [5].
Fusarium wilt of chickpea can be managed by using resistant varieties, healthy chickpea seed, crop rotation, biological control, and fungicides, adjusting sowing dates, and adopting integrated management practices [6].Seid and Melkamu [7] reported that growing resistant and moderately resistant varieties treated with fungicides sown at recommended seeding rate could reduce mortality caused by chickpea fusarium wilt.In spite of the occurrence of fusarium wilt in commonly grown varieties in most parts of the country every year, limited research efforts have been made to find out sources of resistance and develop suitable methods for its management in Ethiopia.
erefore, the main objective of this study was to evaluate the effects of chickpea varieties and seed dressing with fungicides on fusarium wilt development.

Description of Study Area, Treatments, and Experimental
Design.
e field experiment was conducted during 2015 and 2016 cropping seasons on fusarium wilt sick plot at the Adet Agricultural Research Center (AARC) in the northwestern part of Ethiopia.
e center is located 11 °17'N latitude, 37 °43'E longitude and lies at an altitude of about 2150 m.a.s.l.According to the meteorological data of the center, the average annual rainfall is 1250 mm ranging between 860 mm and 1771 mm with the average maximum and minimum temperature 27.5 °C and 12.2 °C, respectively [8].
e treatments were consisted of four chickpea varieties, namely, Shasho, Arerti, Marye, and local, two seed dressing fungicides, namely, Apron Star and mancozeb, and untreated local chickpea (control).e design was Randomized Complete Block Design (RCBD) with three replications.e gross plot size was 4 m 2 (1.6 m × 2.5 m), and the path plots and between blocks were 1 m and 1.5 m, respectively.Plots were prepared and fertilized with 100 kg•ha −1 diammonium phosphate at planting.e seeds were planted at spacing of 10 cm between plants and 40 cm between rows.Both the fungicides were used at the rate of 3 g for a kg of seeds, and the treated seeds were shade-dried overnight before sowing.All the recommended cultural practices were also applied in the field.

Data Collection.
In the experiment, field observations of naturally occurring fusarium wilt incidence were done at 7day interval at sick plot based on percent of wilt incidence in each plot.Initial recording data for fusarium wilt disease incidence was done when wilting symptoms were visible on the three to five basal leaves of the plants.
Disease incidence (DI) on each experimental unit was calculated by using the following formula: DI(%) � number of plants that shows wilt symptoms number of both disease infected plants and healthy plants   × 100. ( Area under disease progress curve (AUDPC) was calculated for each treatment from the assessment of disease incidence by using the following formula: where x i is the disease incidence in percentage at i th assessment, t i is the time of the i th assessment in days from the first assessment date, and n is the total number of disease assessments [9].Relative yield loss (RYL) was calculated using the formula of Robert and James [10]: where RYL � relative yield loss (reduction of the yield and yield component), YP � yields which were obtained from plots with maximum protection, and YUP � yields which were obtained from plots with minimum protection.Relative yield loss with different treatments was calculated with reference to the best protected plot.

Statistical Analysis.
Analyses of variance (ANOVA) for the effects of varieties and fungicides on fusarium wilt disease incidence, AUDPC %-day, relative yield loss, and grain yield were used to compare the level of resistance among evaluated varieties and fungicides.All analyses were performed using statistical package SAS system, version 9.2 [11].Least significant difference (LSD) values were used to separate differences among treatments means at 5% probability level.

Results and Discussion
e data of two cropping seasons were analyzed separately, but the result showed that there was no significant difference between the two season outputs in the experiments, so that the two season data were combined and analyzed together.
3.1.Disease Incidence.Significant differences at p < 0.05 were observed among varieties and fungicides on disease incidence percentage.Among the main effects, the maximum disease incidence of 53.45% was recorded from local chickpea while the minimum disease incidence of 29.41% was recorded from Shasho variety (Table 1).Shasho variety followed by Arerti had lower wilt incidence over the local [12].On the contrary, the maximum disease incidence of 52.31% was recorded from untreated plots while the minimum disease incidence was ranged from 32.76% to 37.38% recorded from Apron Star and mancozeb treated plots, respectively (Table 1).
Landa et al. [13] pointed out seed dressing chemical is one of the most important factors that reduces the effects of fusarium wilt disease.
e chickpea plants treated with fungicides gave 26-34% disease incidence of fusarium wilt as compared to untreated plants, which have 80% incidence.Similarly, the application of fungicides brought tremendous increment in plant growth as well as grain yield.Kamdi et al. [14] stated that seed dressing fungicide applications in chickpea plants were very effective; they have not only suppressed the pathogen activities but also increased the 2 International Journal of Agronomy plant growth and grain yield (almost double than the control plants).Analysis of variance showed that disease incidence was significantly affected by chickpea varieties, fungicides, and their interaction at p < 0.05 (Table 2).Among the interaction effects, the maximum disease incidence of 65.62% was obtained from untreated local chickpea, followed by untreated Marye variety while the minimum disease incidence of 23.41% was recorded from Shasho variety treated with Apron Star but they did not show any significant difference among Shasho variety treated with mancozeb and Arerti variety treated with Apron Star fungicides that of 26.68% and 28.39%, respectively (Table 2).

Effect of Varieties and Fungicides on the Progress of Fusarium Wilt.
e disease progress curve on chickpea varieties at two seed dressing fungicides, i.e., Apron Star and mancozeb and untreated is given in Figure 1. e fusarium wilt incidence increased from the initial to final assessment dates, and the curve showed an increasing trend of disease development for effects of four chickpea varieties in each seed dressing fungicide in the assessments.Hence, the result showed that the rate was slower on Shasho followed by Arerti variety compared to local and Marye variety (Figure 1).
On the contrary, the disease progress curve on fungicides at four chickpea varieties, i.e., Shasho, Arerti, Marye, and local is given in Figure 2. e curve showed an increasing trend of disease development for effects of seed dressing fungicides in each chickpea variety in the assessments.Hence, the result showed that the rate was slower on chickpea treated with Apron Star, followed by the ones treated with mancozeb fungicides compared to untreated plots (Figure 2).

Area under Disease Progress Curve (AUDPC).
Among the main effects, the minimum AUDPC %-day value were recorded from Shasho variety, followed by Arerti and Marye varieties while the maximum AUDPC %-day value was recorded from local chickpea (Figure 3).ese mean that Shasho variety has more resistance against to the fusarium wilt disease compared to other tested varieties.
On the contrary, the minimum AUDPC %-day value was recorded from the chickpea variety treated with Apron Star, followed by mancozeb fungicides while the maximum AUDPC %-day value was recorded from untreated plots (Figure 3). is is because the chickpea variety treated with Apron Star fungicides had more resistance against to the fusarium wilt disease incidence compared to mancozeb and untreated.
Analysis of variance showed that AUDPC %-day was significantly affected by chickpea varieties, fungicides, and their interaction at p < 0.05.Among the interaction effects, the maximum AUDPC %-day value was recorded from untreated local chickpea, followed by local chickpea treated with mancozeb fungicides while the minimum AUDPC %-day value was recorded from Shasho variety treated with Apron Star fungicides, followed by Arerti treated with Apron Star and Shasho treated mancozeb fungicides (Figure 4).

Grain Yield of Chickpea.
Grain yield was significantly affected by chickpea varieties, fungicides, and their interaction at p < 0.05.Among two-way interaction effects, the maximum grain yield of 4.55 t/ha was recorded from Shasho variety treated with Apron Star, followed by Arerti variety treated with Apron Star which resulted in grain yield of 3.94 t/ha while the minimum grain yields of 0.21 t/ha were recorded from untreated local chickpea, followed by untreated Marye variety which resulted in grain yield of 0.75 t/ha (Table 3).
Yigitoglu [15] reported that the maximum grain yield was obtained from resistant variety treated with seed dressing fungicides.Apron Star seed-treatment gave minimum disease incidence of fusarium wilt and maximum grain yield [14].Similarly, Subhani et al. [16] reported that applications of seed dressing fungicide significantly increased the plant growth and yield and also decreased chickpea fusarium wilt incidence.

Relative Losses in Grain
Yield.Among two way interaction effects, the maximum relative grain yield losses of 95.38% and 83.52% were obtained from untreated local chickpea and untreated Marye variety, respectively, while the minimum relative grain yield loss was obtained from Shasho variety treated with Apron Star fungicides which result of insignificance loss, followed by Arerti variety treated with Apron Star fungicides, which result of 13.41% LSD � least significant difference; CV � coefficient of variation; means followed by the same letter did not show significant difference at p < 0.05 according to least significant difference.LSD � least significant difference; CV � coefficient of variation; means followed by the same letter did not show significant difference at p < 0.05 according to least significant difference.
International Journal of Agronomy 3   International Journal of Agronomy (Table 3).Grain yield losses were reduced through chickpea seeds treated with seed dressing fungicide as compared to untreated check of the respective variety [3].

Conclusion
e findings of the present study suggest that the adoption of resistant variety Shasho with fungicide Apron Star seedtreatment may result in reduced fusarium wilt disease progress with a corresponding increased grain yield of chickpea.Further, undoubtedly the fusarium wilt appears to be an important disease that calls for better attention in the study area in terms of economical management with fungicide seed-treatment and use of resistant varieties.e variety Shasho appears to have better resistance against the fusarium wilt disease; therefore, its genetic resistance needs to be investigated further by repeating the experiment for one more cropping season.

Data Availability
e data used to support the findings of this study are available from the corresponding author upon request.

Figure 2 :
Figure 2: Response to different fungicides by the four varieties of chickpea: (a) Shasho, (b) Arerti, (c) Marye, and (d) local check variety, on disease progress of fusarium wilt incidence.

Table 2 :
Two-way interaction effects of chickpea varieties and fungicides on disease incidence of chickpea fusarium wilt.

Table 1 :
Main effects of chickpea varieties and fungicides on disease incidence of chickpea fusarium wilt.

Table 3 :
Two-way interaction effects of chickpea varieties and fungicides on grain yield of chickpea and their corresponding losses due to chickpea fusarium wilt.� least significant difference; CV � coefficient of variation; means followed by the same letter did not show significant difference at p < 0.05 according to least significant difference.
LSD 6International Journal of Agronomy