Effects of Varieties and Different Environments on Growth and Yield Performance of Shallot ( Allium cepa var. aggregatum )

Shallot ( Allium cepa var. aggregatum ) is one of the major cash crops produced in the Amhara region, including East Gojjam Zone, Ethiopia. However, the shallot is being out of production, and there are limited research eforts concerning the infuence of the growing environment on shallot varieties. Tus, the objective of the study was to identify adaptable and high-yielding shallot varieties across diferent agroecologies/location in the East Gojjam Zone of Ethiopia. Te experiment was conducted at three locations (Debre Markos, Wonka, and Yelam Gej) during 2019/20 and 2020/21 growing seasons. Te study consists of four shallot varieties (Minjar, Huruta, Negelle, and local). Te experiment was conducted in a randomized complete block design with three replications. Data on growth, yield, and yield component parameters were recorded and analyzed using SAS Computer Software version 9.0. Te present results indicated that the highest plant height, leaf length, number of shoots per plant, number of bulblets per bulb, average bulb weight, total yield, and marketable yield per hectare were recorded from improved shallot varieties Minjar, Negelle, and Huruta. Tus, Minjar, Negelle, and Huruta were better performed for growth, yield, and yield components at all testing locations. Tus, Minjar, Negelle, and Huruta were found to be superior in yield and yield components at all testing locations and were thus suggested to be used by the growers in the study area. It would be advisable to evaluate the varieties in the participatory varietal trail for further dissemination of varieties to shallot growers in the study area.


Introduction
Shallot (Allium cepa var. aggregatum) belongs to the family Alliaceae and is believed to be originated from West Asia [1]. Shallot is primarily consumed for its unique favor or ability to enhance other foods' favors. Shallot had a signifcant contribution to the nutritional value of the human diet and has medicinal properties. It is rich in sugar, protein, fat, calcium, potassium, phosphorus, sulfur, iodine, fber, silicon, and vitamins [2,3]. It reduces the cholesterol in the blood, and its juice is given in pulmonary tubers, close rheumatism, sterility, impotency, cough, and red eyes [4].
Te bulbs of the shallot plant produce more than two and up to 15 small bulbs (bulblets), which are in aggregated form [5]. Shallot is tolerant to a wide range of soils with a pH of 6-7; loose, sandy soils with a high level of organic content are preferable [6]. In Ethiopia, shallot has long been grown by subsistent farmers in the mid-and high altitudes (1800 to 2200m.a.s.l) for seasoning foods and as a source of income [7].
Ethiopia has enormous potential for the cultivation of horticultural crops in general and vegetables in particular on a small scale as well as for commercial production. Shallots are the most widely cultivated bulb crops in diferent parts of Ethiopia as a substitute for bulb onions. Te cultivation of shallot is preferred by farmers compared with onion for its ability to propagate in a vegetative way, shorter growth cycle, disease tolerance, better storage life, and distinct favor that persists after cooking [8,9]. Shallot has a wide range of climatic and soil adaptations and is cultivated under rain-fed and irrigated conditions in diferent agroclimatic regions [10,11]. It is one of the most widely cultivated cash crops and is traditionally cultivated in some parts of the country (Hararge, Shoa, Arsi, and Gojjam, etc.) by small farmers as an income-generating spice crop for favoring local dishes.
According to Getachew and Asfaw [12], BoARD [13], and Ademe et al. [14], the shallot is among the major cash crops produced in the Amhara region including East Gojjam Zone under irrigation and rain-fed conditions. In Ethiopia, the total area under shallot reached 14758.51 ha of land, and the production is estimated to be over 132424.68 tons of fresh bulbs with an average yield of 8.97 t/ha (CSA, 2017). Despite its high economic importance, the national average bulb yield of shallot under farmer's condition is about 8.97 t/ ha with poor bulb quality (mixed varieties, varying in size, color, shape, and storability) compared to 25 t/ha obtained under good management practice. In the Amhara region, the area covered by shallot is 12339.39 ha with a productivity of 12.84 tons/ha. However, its productivity is lower than the world average of 19.32 t/ha [7,15,16].
Tere are several factors that limit shallot productivity. Tese include a lack of improved technology, low attention to the crop, poor agronomic practices, and availability of quality planting materials, and a lack of improved production, and protection technologies [7]. Furthermore, the lack of improved preharvest and postharvest management practices, diseases, and insects have also contributed to low yield and quality [17]. Due to these factors in the study area, full production capacity (yield potential) has not been exploited, and research eforts are inadequate and insufcient on the infuence of diverse growing environments on shallot varieties. Hence, to reduce shallot production problems, diferent cultivars often require specifc agroecological conditions for maximum production potential. Tus, the objective of the study was to identify adaptable and high-yielding shallot varieties across diferent agroecologies in the East Gojjam Zone of Ethiopia.

Description of the Experimental Area.
Te experiment was conducted at three diferent agroecologies (Debre Markos, Wonka, and Yelam Gej districts) in two consecutive years (2019/2020 and 2020/2021). Te locations were selected based on the shallot production potential and represent distinct agroecologies. Te three selected major shallot-producing districts in the East-Gojjam Zone are as follows: Debre Markos testing site is geographically located at 10°19′59″N 37°44′53″E. Te altitude of the study area was 2450 m.a.s.l. Te minimum and maximum temperatures were 11°C and 24°C, respectively. Te minimum and maximum rainfalls were 1300 mm and 1380, respectively. Te soil type of the study site is nitisols and clay in its textural class [18].
Wonka testing site is geographically located at 10°10′00″ and 10°40′00″N latitude and 37°30′00″ and 37°54′00″E longitude, and the altitude of the testing site was 2300m.a.s.l. Te minimum and maximum temperatures were 6.9°C and 22°C, respectively. Te mean annual rainfall amount ranges between 1157.7 and 1753.0 mm. Te soil type of the study site is nitisols.
Yelam Gej testing site is geographically located at 10°02′33″N 37°44′33″E and 2181°m.a.s.l. Te minimum and maximum temperatures were 16°C and 30°C, respectively. Te average rainfall was 750 mm. Te soil type of the study site is nitisols.
Te rainfall was well distributed throughout the cropping season; however, no rain was experienced during January, February, March, and April during both seasons (Figure 1(a)). Te highest maximum temperature recorded from Debre Markos testing site, followed by Yelam Gej and Wonka during 2020/2021 growing season and from Yelam Gej during 2021/2022 season (Figure 1(b)). Te minimum mean temperature was recorded from Wonka testing site, followed by Debre Markos and Yelam Gej during 2020/2021 growing season, while during 2021/2022, the minimum mean temperature was recorded from Debre Markos testing site from January to April (Figure 1(c)).

Experimental Materials and Procedures.
Te experiment consists of four shallot varieties such as Huruta, Minjar, Nagelle, and local as a check which are propagated by bulbs used as planting material. Te planting materials except local were obtained from a reliable source Debre Zeit Agricultural Research Center (DZARC). Te local variety was purchased from the Debre Markos town market (Table 1). Te experiment was conducted for two consecutive years from 2019/2020 to 2020/ 2021 at three testing sites. Four shallot varieties were laid out in a randomized complete block design (RCBD) with three replications in each location. Treatments were assigned to the experimental plots randomly.
Bulbs were obtained and stored for planting. At planting time, cured, medium-sized (20 to 30 g) bulbs were sorted and graded. Healthy and clean bulbs of each variety were selected and planted [8].
Irrigation water was applied to all plots on the day of planting by using a watering cane once a day (early morning). Te bulbs/seedlings were spaced 40 cm × 20 cm × 10 cm double row, row, and plants, respectively. Te space between the block and between plots will be 1 m and 0.5 m, respectively. Tere were four rows per plot and 10 plants per rows for a total of 40 plants per plot. Te size of each experimental plot was 1 m 2 (1 m wide and 1 m length). Fertilizers were applied according to the national recommendation at the rate of 200 kg DAP at planting and 100 kg of urea. Urea was applied in the split application, 50% of urea the time of planting and the other 50% at one month after planting [19,20].

Data Collected.
Measurements of the growth, yield, and yield component parameters were recorded at physiological maturity and harvesting time.
(1) Plant height (cm): it was measured using a ruler from the soil surface to the tip of the longest mature leaves at physiological maturity (2) Leaf length (cm): it refers to the length of the longest leaf, which was measured using a ruler from the sheath to the tip of the leaf at physiological maturity  (3) Leaf number per plant: it refers to the total count of leaves per plant at maturity (4) Stem number per hill: it was measured by counting the number of stems/hills (5) Days to physiological maturity: it refers to the actual number of days from planting to a day at which more than 85% of the plants in a plot showed yellowing of leaves [21] (6) Bulb neck diameter (cm): it was measured by using a caliper at physiological maturity (7) Average bulb weight (g): it was computed by weighing ten marketable bulbs after curing and calculating the average (8) Te number of bulblets per bulb: it was the average number of bulblets of 10 bulbs from each plot (9) Bulb length: the average diameter of 10 bulbs from each plot was measured after curing using a digital caliper (10) Bulb diameter (mm): it was measured at the widest point (middle portion) of the bulb and the average diameter of 10 bulbs from each plot will be measured after curing using a digital caliper (11) Marketable bulb yield (t/ha): bulbs having a diameter of ≥18 mm were considered as marketable yield according to the procedure followed by Woldetsadik et al. [8] (12) Unmarketable bulb yield (t/ha): damaged bulbs <18 mm diameter will be graded as unmarketable according to the procedure followed by Woldetsadik et al. [8] In addition, undersized, defected, and diseased will be graded as unmarketable (13) Total yield (t/ha): this was measured from the middle two rows (20 plants) of each plot after curing and transformed to tones per hectare.

Data Analysis.
Te data collected on diferent growth and yield parameters were frst checked for meeting all ANOVA assumptions for normality of distribution and homogeneity of variance and subjected to the analysis of variance (ANOVA) by using the PROC MIXED procedure of the SAS version 9.0 computer software [22]. Varieties and location (agroecology) were considered fxed efects while block and season were considered as random efects. Te combined analysis of variance over seasons and locations was computed for the parameters that show homogeneous variances. For the rest of the parameters, separate analysis was done for each year and for each location to identify their efect on the response variables. Te interaction efects between the main efects (variety by location) were presented only when there is a statistically signifcant diference. In the absence of signifcant interactions, the main efects were presented. When the analysis showed signifcant (p ≤ 0.05), mean separation was carried out using the LSD (least signifcance diference test) at a 5% signifcance level [23].

Results and Discussion
Te efect of varieties and growing environment was evaluated with respect to growth, yield, and yield attributes of shallot and the results obtained are presented accordingly.

Plant Height (cm) and Leaf Length (cm).
Te combined analysis of variance over the year and location indicated that plant height was signifcantly (p < 0.01) diferent between varieties and (p < 0.0001) locations. However, the interaction between varieties, growing season, and location did not show a signifcant diference (Table 2). On the other hand, leaf length was signifcantly (p < 0.01) diferent between varieties, growing season, and location. However, the locations and interactions between varieties and locations did not show a signifcant diference (p > 0.05) (  (Table 4). Te highest plant height and leaf length were recorded at Debre Markos testing site compared to Wonka and Yelam Gej. Te diference between varieties for plant height and leaf length was due to the genotypic diference and their response to diferent environmental conditions. Te result is in agreement with the fndings of Hailu et al. [24], and Esuyawkal-Moges and Biruk-Masrie [25], who reported a signifcant diference between shallot varieties on plant height and leaf length. Hailu et al. [24] also reported local variety attained the shortest height.

Leaf Number per Plant.
Analysis of variance for the combined data indicated that varieties, growing environment, and season had shown highly signifcant diference (p < 0.001) for the mean number of leaves per plant at physiological maturity. Te interaction of growing location by season very highly signifcantly afects the number of leaves per plant. However, the interaction of varieties with growing season and location did not signifcantly infuence leaf number per plant (Table 2).
During the year 2019/2020, the highest mean leaf number per plant was recorded from variety Minjar at Debre Markos (11.33), which was statistically similar to varieties Minjar (9.58) and variety Negelle (10.91) at the Wonka site. Te lowest and statistically similar leaf number per plant was recorded from local checks at Debre Markos, Wonka, and Yelam Gej testing sites. On the other hand, during 2020/21 the leaf number per plant was not signifcantly diferent (Table 5). Te variation in growth parameters among varieties might be due to their genetic diferences. Te result is in agreement with the fndings of Esuyawkal-Moges and Biruk-Masrie [25], who reported the diference between varieties for leaf number per plant. Shimeles and Lemma [26] also illustrated shallot varieties were the diference in response to leaf number per plant at two testing locations.
Hailu et al. [24] also reported the diference in leaf numbers between shallot varieties. However, in contrast to the present study, they reported that Minjar varieties produced a small number of leaves per plant.

Number of Shoots per Plant.
Te analysis of variance revealed that the main efects of variety, growing location, and season highly signifcantly (p < 0.01) infuenced number of shoots per plant of shallot (Table 2). Te main efect result indicated that the highest number of shoots per plant was recorded from variety Minjar, Negelle, and Huruta while the lowest number of shoots per plant was recorded from a local check. In addition, the maximum number of shoots per plant was recorded from the Wonka testing site, followed by the Debre Markos and Yelam Gej testing sites. During 2020/ 2021 growing season the maximum number of shoots per plant was recorded ( Figure 2). Te variation in shoot number per plant between varieties might be due to the fact that diferent varieties, with their genetic makeup variation responded diferently to diferent factors. Te diference on shoot number per plant might be due to inherent variations in the number of bulblets per bulb on onion which is infuenced by genetically [27].   Figure 3). Local check was a longer maturity day by 3 and 4 days than the earliest maturing variety Negelle and Huruta, respectively. Te Wonka testing site matures earlier by 23 days compared with Debre Markos testing site. Te variation of maturity date between growing conditions was due to the highest maximum temperature at the time maturity from September to November during both seasons ( Figure 1). Similarly, the variation of maturity date between shallot varieties might be due to their inherent genetic diference.
Additionally  (Table 6). Te earliness of physiological maturity in location was due to the genotypic efect of varieties and the diference in temperature of growing locations.   6 International Journal of Agronomy   International Journal of Agronomy Similar results were recorded by Getachew and Asfaw [12] who reported days to maturity of shallot showed variations from 95 days to 126 days. Kimani et al. [28] also detected variations in days to maturity among onion cultivars, and the values are afected by the growing environment. (cm). Two years of the combined analysis indicated that the main efects of varieties, location, and the interaction of varieties and growing location were signifcantly (p < 0.01) infuencing bulb neck diameters ( Table 3).

Bulb Neck Diameter
Te results indicated that the highest bulb neck diameter of shallot was recorded from variety Minjar (1.46 cm) at the Debre Markos testing site, followed by Negelle, Huruta, and local varieties at the Debre Markos site while the lowest bulb neck diameter was obtained from local check (0.55 cm) at Yelam Gej testing site (Table 7). Te signifcant diference between bulb neck diameters of shallot varieties might be attributed to the genotypic variation and their interaction with growing environment [29].

Number of Bulblets per Bulb.
Number of bulblets per bulb of shallot was very highly signifcantly (p < 0.0001) afected by the main efects of varieties. However, the interaction of varieties, growing environment, and season were not signifcantly infuenced the number of bulblets per bulb of shallot Table 3).
Te maximum number of bulblets (7.91) was recorded from the variety Minjar which was statistically similar to Huruta (7.36). Te lowest bulblets per bulb were obtained from the local variety (5.73) which is on par with that of Negelle (Table 8). Te diference in varieties in bulblet numbers might be due to the diferences in their genetic makeup. Similar results were reported by Shimeles [30] and Shimeles and Lemma [26] who reported that varieties of shallot difered in bulblet number in response to growing environments/location. In addition, Shimeles [30] and Tagele et al. [31] indicated that the number of bulblets is a very good measurement of shallot bulb quality and a potential indicator for the identifcation of shallot lines from a single-bulb onion crop. Tabor et al. [32] also reported that shallots grown from seeds or seedling clusters contain an average of 1-3 bulblets per bulb.

Average Bulblet Weight (g).
Te analysis of variance revealed that the average bulblet weight of shallot was highly signifcantly (p < 0.001) infuenced by the main efects of varieties, growing location, and season. In addition, the interactions of the location and verities and location by growing season were also highly (p < 0.001 afected average bulb weight of shallot (Table 3).
Separate analysis by location showed, at Debre Markos, the largest average bulblet weight was recorded from Variety Minjar (297.00 g), Negelle (257.16 g), and Huruta (239.66 g) while the lowest average bulblet weight (106.1 g) was recorded for local varieties. Similarly, at Wonka Minjar (261.67 g) Negelle (200.00 g) and Huruta (231.67 g) recorded the maximum weight of average bulblets. Te lowest average bulblet weight (100.00 g) was recorded from the local variety at Yelam Gej, and the largest average bulblet weight was recorded from Minjar (117.00 g), Negelle (257.16 g), and Huruta (239.66 g) (Table 9) while the lowest average bulblet weight (106.1 g) was recorded for local varieties. Minjar, Negelle, and Huruta had consistently recorded the maximum average bulb let weight in all locations, except Huruta in Yelam Gej.

Bulb Length (cm).
Varieties and growing location revealed a highly signifcant (p < 0.001) efect on the mean bulb length of the shallot plant. However, there is no interaction efect on shallot varieties, growing location, and season (Table 3). Te longest bulb length (6.72 cm) was recorded from variety Minjar at Debre Markos; however, it was statistically similar to variety Negelle (6.0708 cm) at Debre Markos and Minjar and Negelle at Wonka and Yelam Gej. However, the shortest bulb length (3.9458 cm) was recorded from the local variety at Wonka, which was statistically similar to the same variety at Debre Markos (Table 10).
Tis variation of bulb length between varieties and diferent location might be due to the variation among varieties inherent characteristics and their interaction with the environment. Similar results are reported by Islam et al. [33], who explained signifcant genotypic variation of bulb length on onion.
3.9. Bulb Diameter (cm). Te varieties, growing location, and season showed a highly signifcant (p < 0.01) diference in the bulb diameter. Moreover, the interaction efect of variety with location and varieties with growing season signifcantly (p < 0.05) infuence the bulb diameter (Table 3).
Te maximum bulb diameter (3.38 cm) was recorded from varieties Minjar and Negelle at Debre Markos, while the lowest bulb diameter was recorded from local check in all growing environments (Table 10). Te diference in varieties in bulblet numbers and bulb diameter might be due to the diferences in their genetic makeup. Similar results were reported by Shimeles [30]; Shimeles and Lemma [26], Biru [34], Esuyawuka-Moges, and Biruk-Masrie [25] reported that varieties of shallot difered in bulb diameter in response to growing environments/location.

Average Bulb Weight (kg).
Tere was a highly signifcant (p < 0.01) diference between varieties, growing location, and season on average bulb weight (Table 3). However, the interaction of variety and location were not signifcantly (p > 0.05) afect a bulb weight. Te maximum mean bulb weight was obtained from variety Minjar (0.1081 kg) during 2019/2020 and (0.1606 kg) during 2020/2021 while the lowest average bulb weight was recorded from the local variety in both years (Table 11). Te diference between the mean weights of bulbs might be due to their genotypic diference. Te present result is similar to the fndings of Shimeles [30], Shimeles and Lemma [26], and Esuyawkal and Biruk-Masrie [25], who reported the diference in mean fresh bulb weight among varieties. Kokobe and Hirut [35] also reported a signifcant diference in average bulb weight between onion varieties under the Hawassa condition.
3.11. Total Dry Bulb Yield (t/ha). Te analysis of variance showed a signifcant (p < 0.05) diference between varieties, growing location, and season on the dry bulb yield of shallot (Table 3). Moreover, the interaction efects of the three factors were highly signifcantly (p < 0.01) infuenced total dry bulb yield. At Debre Markos, the maximum total dry bulb yield was obtained from the variety Minjar (35.9844 t/ ha), which was on par with Negelle (27.2185 t/ha) and Huruta (25.5055 t/ha) while the lowest total bulb yield per hectare was obtained from the local variety (18.7122 t/ha) which was statistically similar to that of Negelle and Huruta. At Wonka, the maximum total dry bulb yield was obtained from varieties Minjar (24.88 t/ha 1 ), Negelle (23.9630 t/ha), and Huruta (20.7407 t/ha) while the lowest total fruit yield per hectare was obtained from local (12.7778 bt/ha). At Yelam Gej, the maximum total dry bulb yield was obtained from varieties Minjar (14.4601 t/ha), and Huruta (13.5821 t/   International Journal of Agronomy 9 ha), while the lowest total dry bulb yield per hectare was obtained from the variety local (9.7895 t/ha) and Negelle (10.8262 t/ha). Te maximum mean combined yield was recorded by varieties Minjar, Negelle, and Huruta at Debre Markos and Wonka, Minjar, and Huruta at Yelem Gej. Minjar was found consistently the highest yield compared to the local check at all locations. Negelle and Huruta were also found to be better. Tis may indicate that Minjar is a suitable variety over a range of environmental conditions (Table 12). Te maximum yield was obtained from the Minjar variety. Tis was due to the highest bulblet number per bulb, the highest average bulblet weight, and maximum average bulb weight plant. In addition, this might be because the varieties have diferent yield potentials as well as genetic and environmental interaction efects. Te present result is in agreement with the fndings of Shimeles and Lemma [26], and Esuyawkal-Moges and Biruk-Masrie [25] reported signifcant yield diferences among shallot varieties. Shimeles [30] also reported the diference in mean bulb yield of varieties from diferent locations Zewai, Kulumsa, and Melkassa. Ademe et al. [14], Hailu et al. [24], and Huruta and Minjar gave higher bulb yields and yield components in Aneded Woreda, western Amhara, and Wolaita Zone, Southern Ethiopia. Likewise, Tabor [36] conducted a multilocation trial, and the result showed a signifcant diference between location and variety. Tesfa et al. [37] also reported that all improved cultivars had higher total bulb yields than the local landrace.

Marketable and Unmarketable Bulb Yield (t/ha).
Te analysis of variance for the variety, growing location, season, and their interaction showed a signifcant (p < 0.05) difference in marketable bulb yield (Table 3). Variety Minjar recorded the highest marketable bulb yield (35.1092 t/ha) at the Debre Markos site, which was statistically similar to Negelle (26.0130 t/ha) and Huruta (23.8324 t/ha), while the least total bulb yield per hectare was recorded from a variety local at the Wonka testing site (Table 13). Marketable bulb yield diferences between cultivars could be due to genetic diferences, which control plant growth and development and indirectly determine bulb size through the amount of carbohydrates synthesized and made available for storage in bulbs. Similar results are recorded by Ademe et al. [14], Hailu et al. [24], Shimeles and Lemma [26], and Esuyawkal and Biruk [25], who reported that the marketable yield diference was due to genotypic diference. Tesfa et al. [37] also reported that all improved cultivars had higher total marketable yields than the local landrace.

Conclusions and Recommendations
Te salient fndings of the present result indicated that growth, yield, and yield component traits are infuenced by the main efects of varieties, growing location, and season. Te highest plant height, leaf length, number of shoots per plant, number of bulblets per bulb, average bulb weight, total yield, and marketable yield per hectare were recorded form improved shallot varieties Minjar, Negelle, and Huruta. While local variety is also good in total yield per hectare. However, it is small in bulb length, bulb diameter and marketable yield. Tus, Minjar, Negelle, and Huruta were found to be superior in yield and yield components at all testing locations and were thus suggested to be used by the growers in the study area. Te local cultivar would also have maintained for its yield traits for future breeding improvement activities. Since the study was the frst of its kind in the study area, it would be advisable to evaluate the varieties in a participatory varietal trail for further dissemination of varieties to shallot growers.

Data Availability
Te data used to support this study are available from the corresponding author upon reasonable request.

Conflicts of Interest
Te authors declare that they have no conficts of interest.  International Journal of Agronomy 11