Growth and Productivity of Different Potato Cultivars

During the experimental years of 2017 and 2018 eight potato cultivars were evaluated for their growth traits and productivity in tuber yield. The potato cultivars used in these experimental seasons were; Bubu (as a standard check), Chiro, Gebisa, Belete, Gudene, Badasa Jarso and Dedafa. The first six consecutive potatoes are improved cultivars which were released by Ethiopian research institute and University while the last two potatoes were collected from farmers and cultivated as local (native) cultivars. The objective of this study was to compare the growth and productivity potato cultivars grown at eastern regions of Ethiopia. The results revealed that performance of improved potato cultivars were high in both evaluated yield related traits and average tuber yield. The performances of evaluated potatoes were not similar among cultivars and within cultivar throughout experimental seasons. The experimental design was a randomized block design in three replications. The field management; seed tuber selection, land preparation, planting, fertilizer application method and amount, ridging, weeding, cultivation, harvesting, data collection method and collected data analysis has been carried out for all potato cultivars in similar manner. Potato tubers from four middle rows were analyzed for parameters such as tuber yield, tuber number, marketable and total tuber yield. The highest tuber yield was revealed with cultivar Bubu (39.4 t ha) while the lowest with Jarso (20.89 t ha). The highest tuber number was showed with cultivar Badasa (12.73 plant) and the lowest with Belete (7 plant). Hence, there were no correlation between average tuber yield and number.


Introduction
With the increase in Ethiopia's population and decrease in arable land, food security issues have become more prominent.Potato (Solanum tuberosum L.) is one of the most widely grown food crops after the three cereals viz., maize, rice and wheat (Vleeshouwers et al., 2011).Potato is an important food and cash crop in Eastern and Central Africa, playing a major role in national food security and nutrition, poverty alleviation and income generation, and; provides employment in the production, processing and marketing sub-sectors (Lung'aho et al., 2007).In Ethiopia, potato crop is being cultivated regularly each year on the 69,610.81area in hectares 9,689,696.44,production in quintals 139.20, yield (qt/ha) during 2017/18 (FDRE CSA.2017/18).In the past, in Eastern Ethiopia, potato was cultivated in small gardens, but right now this crop is being cultivated on a large scale.
Ethiopia is endowed with suitable climatic and edaphic conditions for high quality potato production.Moreover, many improved cultivars with on-farm yield potential of 19-38 tonnes ha -1 were developed by research centres and demonstrated to farmers for production (Gebremedhin et al., 2008a).The low hectarage and yield of potato in Ethiopia are attributed to many factors.The major ones are lack of well adapted and high yielding cultivars, availability and high cost of seed tubers, inappropriate agronomic practices, and lack of marketing and suitable post-harvest management facilities as well as insect pests and disease (Gildemacher et al., 2009a).
The production of improved potato cultivar is low while many potato growers are cultivating local cultivars to sustain their livelihood and profit generation from this crop.However, currently some potato growers are getting awareness through training, demonstrations and farmers participatory research from different Institute of Agricultural Research and Non-governmental seed sectors to produce improved cultivars.Farmers that cultivate local varieties are reported to get yields equivalent to those that cultivate improved varieties.This might be due to good farm management practices, which may be stimulated by the prospect of export market (Adane et al., 2010).The comparative performances of the potato cultivars released Ethiopian Agricultural Research Centers and Universities are not elucidated.In addition, little scientific information has been documented on these potato cultivars.For these reasons, there is a need to collect, characterize, evaluate and even promote local potato cultivars or genotypes before they become out of production (Balkaya & Ergun, 2008).Therefore, this study was initiated with the objective of comparing the growth and productivity of improved and local (native) potato cultivars.

Materials and Method
The number of potato cultivars used for evaluation during experimental years of 2017 and 2018 at Haramaya University Raaree research farm of Ethiopia were eight; Bubu (as a check), Chiro, Gebisa, Jarso, Belete, Gudene, Badasa and Dedafa.The experimental design was a randomized block design in three replications.Each potato cultivars were planted in six rows 4 m long, with 0.75 m space between rows and 0.30 m between tubers in a row.The experimental units were distant 1.0 m among each other.Previous crop in both years was wheat and corn in 2017 and 2018, respectively.Potato seed tuber planting was done in manual method on the first week of April for both years of experimental period.Potato yield of four inner rows was analyzed for all cultivars.In both years, each experimental plot received the following amount of fertilizers: 100 kg ha -1 Urea (CO [NH 2 ] 2 ) (46% N) and 150 kg ha -1 TSP (Triple-Super Phosphate), which constitutes about 46% P 2 O 5 , were used as a source of inorganic fertilizer in basal application method.Urea was applied two times; ½ during planting, and ½ at stage of flower initiation while TSP was applied during planting as a full doze.The study was conducted in field (Stolon number, potato tuber number, and tuber yield).All valuations were completed in potato tubers collected from four middle rows from experimental plots.The data were subjected to analysis of variance (ANOVA) of RCBD in factorial arrangements for each location using the general linear model of Genstat 16 th edition updated version.Treatment means that exhibited significant differences was separated using Fisher's unprotected least significant difference test at 5% level of significance.
The duration of vegetative time (maturity) is a potato cultivars characteristic affected by planting season, climatic condition and implemented cultivation rehearses.There are considerable differences with respect to the vegetation time, depending on the cultivars peculiarities.In the ecological circumstance of Haramaya, the vegetation time of potato cultivars ranges from 90 to 130 days, as can be revealed in Table 1.Note.Means with the same letter(s) within a column are not significantly different at 5% level of significance.NS = non-significant difference, LSD (5%) = Least significant difference at P = 0.05, and CV (%) = Coefficient of variation in percent.

Marketable Tuber Yield
With respect to the marketable tuber yield, statistically significant differences of different level of significance were revealed among potato cultivars under evaluation and a check (Bubu).The highest tuber yield was apprehended with cultivar Bubu (34.79 t ha -1 ) and Gebissa (33.485 t ha -1 ) while the lowest with variety Jarso (15.93 t ha -1 ).The marketable tuber yield differences between varieties Gebisa (33.485 t ha -1 ) and Gudene (31.275 t ha -1 ) comparing with standard check (34.79 t ha -1 ), were showed statistically no difference.
Statistically highly significant differences were shown with respect to the cultivars planted in different seasons comparing with standard check (Bubu).The highest marketable tuber yield was obtained with potato cultivars planted in 2018 crop growing season, Gebissa (38.22 t ha -1 ) comparing with those planted in 2017, Bubu (31.66 t ha -1 ) (Table 4).Note.Means with the same letter(s) within a column are not significantly different at 5% level of significance.NS = non-significant difference, LSD (5%) = Least significant difference at P = 0.05, and CV (%) = Coefficient of variation in percent.

Tuber Yield
With respect to the tuber yield, statistically significant differences of different level of significance were found among potato cultivars under evaluation and standard check (Bubu).The highest tuber yield was revealed with breeding are adaptability to organic fertilization (adequate root system, rapid juvenal root and plant development, good growth vigour, efficient mineral uptake and use), the ability to produce a good yield in a short growing period (early bulking and ripening, yield stability, acceptable quality, good storability) (Tiemens-Hulscher et al., 2003) and meeting market needs.The selection in the high tuber yield potato variety will include emphasis on rapid establishment, good ground cover, early bulking yield potential and tolerance to changeable humidity and fertility conditions through the better root system and resistance to late blight disease.

Conclusions
According to the ANOVA statistically significant differences of different level of significance were obtained among potato cultivars under evaluation and standard check (Bubu), with respect to the tuber yields, tuber number, etc.The highest tuber yield was revealed with cultivar Bubu (39.395 t ha -1 ) while the lowest with variety Jarso (20.89 t ha -1 ), whereas the highest number of tuber being to variety Badasa (12.7315 plant -1 ) and the lowest one to variety Belete (6.985 plant -1 ).Average potato tuber yield in Ethiopia is low and not in synchronization with possibilities, thus the potato cultivars under these evaluations contributes good indication and opportunities for in country potato growers and processors to use some of these cultivars in order to achieve better yield and quality that will sustain their livelihood, significantly increase their profit and income generation.From the results of the current study it can be concluded that use of improved potato variety with recommended package of production is advised for potato growers in Eastern Ethiopia to sustain their life and increase the income by selling this crop.

Table 3 .
Comparison of eight potato cultivars on yield related traits

Table 4 .
Comparison of eight potato cultivars on marketable and total tuber yield