Evaluation of the Adaptability and Acceptability of Improved Cassava ( Manihot esculenta Crantz ) Varieties in Southwest Ethiopia

DOI: 10.15580/GJAS.2013.8.072613758 The adaptability and acceptability of two improved and one respective promising variety (45/72) of cassava was carried out in Jimma, Agaro and Gera stations during 2009/2011 cropping season. The objective of the study was to test the adaptability, acceptability of the technologies, create awareness to the farmers and evaluate the yield potential of the varieties by yield and farmers’ evaluation criteria. The pooled analysis of variance showed mean square due to varieties showed very highly significant variation (P < 0.01), root diameter(cm) and stem girth(cm) and significant variation (P< 0.05) for number of verticals/hill, canopy diameter (m), root length (cm), weight of above ground plant biomass(kg) and dry matter yield (kg/plot). Highly significant location effect on all traits, except root diameter and stem girth, shows that these traits were highly influenced by change in the environment. Based on the mean data, variability in all traits over locations were varying; ranged from 96 to 209 cm, 3-5, 102-213 cm, 23-56 cm and 1.6-2.8cm for plant height at first branch, number of verticals/hill, canopy diameter(cm), root length(cm) and stem girth(cm) respectively. This shows there exists sufficient variability to develop high yielding cassava variety for production in these districts. The pair-wise comparison of varieties by farmers showed that Variety Kello was selected at the first rank in all tested environments by its merits. Qulle took the second place after variety (Kello) in Jimma and Agaro districts and the third in Gera. Submitted: 26/07/2013 Accepted: 22/08/2013 Published: 29/08/2013


INTRODUCTION
Cassava (Manihot esculenta Crantz) is a tropical woody shrub.It is dicotyledonous plant belonging to the botanical family Euphorbiaceae (Onwueme and Charles, 1994).It originated in North East Brazil with additional centre of origin in Central America.Though the domestication of cassava started in these districts, today the crop is cultivated all over the tropical world (Elias et al., 2001).Of all the tropical root crops, cassava is the most widely distributed and cultivated in different parts of the tropics (Kay, 1987;Onwueme and Sinha, 1991).It is being cultivated as the main source of energy and as the most important staple food crop for over 900 million people of the world (Bainbridge et al., 1997;Ngeve, 1999).
Cassava was first introduced to Ethiopia by the British.Although reliable statistical information on the distribution and production of cassava in Ethiopia is lacking, the crop has been cultivated, particularly in the South, South West, and Western parts of Ethiopia since its introduction.Its use as a food security crop in Ethiopia has increased during and after the 1984 famine (Amsalu 2003;Tewodros 2012).Despite the importance of this crop, the production and productivity is constrained by different biophysical and socioeconomic constraints, such as lack of adapted and improved technologies, land shortage, lack of knowledge and proper utilization of the crop are a few to mention.Therefore, this study was designed to test the adaptability and acceptability of improved cassava technologies with farmers for further scaling up; create awareness to farmers and evaluate the yield potential of the varieties by their evaluation criteria in major growing areas of Jimma, Agaro and Gera districts of Jimma zone.

Field evaluation
Two improved cassava varieties (Qulle and Kello) and promising variety (45/72) was planted at Jimma, Agaro and Gera districts; which is major cassava production areas of Jimma zone.The plot size was 10m x 10m and the distance between plants and rows was 1.0m x 1.0m.In all, other pre and post stand establishment cultural practices in the experimental plots were done until the final harvest of the crop.
Assessments were made on all agronomic and phonological characters recorded immediately after emergence, it included plant population and development (vegetative and flowering), uniformity, plant height at first branch (cm), number of vertical/hill, average canopy diameter/plant (cm), number of roots/plot, average stem girth cm/plant, average length of roots/plant(cm), average root diameter(cm)/plant, total fresh root yield kg/plot, weight above ground plant parts kg/plot, dry matter yield kg/plot and insect and disease incidence, one-five scale were considered as a whole.The harvested material (400gm from each treatment) was oven-dried at 120°C for 72 hours to get the dry matter yield of the product.After measuring the yield, the amount was converted in to kg/plot.The analysis of total fresh root yield and other yield components were performed using SAS computer software packages (SAS, 2001).

Farmers' assessment
Participatory evaluations with farmers were also carried out in the study districts.Initially, 20 households from each district were selected based on meeting with key informants familiar about the crops to evaluate the adaptability and acceptability of cassava varieties before and after harvest.Our relationship with the farmers and key informants developed into a sort of contract based on mutual benefit.Such contracts with farmers appear as pre-requisites for joint learning and platform generation and form the frames on which the research trial and evaluations are developed.Through recurrent discussions, we reiterated our engagement to ground the research on farmers' knowledge, preferences and to set criteria for acceptability, adaptability and selection of the technologies.
A total of 15 different criteria were identified by farmer's based on selection and preferences of the technologies.These criteria were submitted to the group of farmers for further evaluation in each district.Group discussions were made to carefully build on and critically examine derived information from individual farmers of different households.It was also intended to clear conflicting ideas on issues like suitability of the varieties in each district, the yield potential, the growth performances of improved and promising (45/72) varieties.Information obtained from individual, group discussion and the key informants were used to obtain a broad understanding on acceptability, adaptability and sustainable utilization of the technologies in the districts.After harvesting the crop, all tested farmers from each district were evaluated and gave its ranking of the selected varieties based on their selection criteria.The pair-wise ranking (Russell, 1997) method was used to analyze the position of each variety in tested districts by farmers preferences.A matrix table of varieties in each district was constructed.Farmers were asked to compare each variety to the other ones with regards to the values (root yield, palatability and root size etc.) and the priority each farmer gives to the variety.Each variety was compared in turn with each of the other varieties.The process was repeated for all varieties until all possible comparisons had been made.The number of times each variety was found to be more important was counted for each individual farmer.This value represents the individual score for each variety.An aggregation was then realized on the scores for each variety over the farmers participating in the exercise.This aggregated score represents the district score.The ranking of these scores provides the position of the varieties in the district.The same process was applied by farmers to consider variety choice in all tested districts.

Field experiment
The analysis of variance over locations (Table 1) indicated that out of the 10 traits studied, mean square due to varieties showed highly significant variation (P <0.01) for 2 traits and significant variation (P<0.05) for number of verticals/hill, canopy diameter (m), root length (cm), weight of above ground plant parts (kg/plot) and root dry matter yield (kg/plot).Highly significant location effect on all traits, except root diameter and stem girth, shows that these traits were highly influenced by change in the environment.The significance of location effect was expected as Jimma, Agaro and Gera vary for their soil type, average annual rainfall, average temperature and etc.In all tested locations, the variability in total fresh root yield (kg/plot) was not significant for analysis.The variability of treatments in tested locations for yield indicates that varieties containing high yield can be developed if desired.
Based on the mean data over locations (Table 2) indicated that the total fresh root yield performance of treatments (489.8kg/plot) was lower than that of Agaro (622.3 kg/plot) and higher from Jimma (361.1 kg/plot) and Gera (486.2 kg/plot).Variability in all traits over locations was varying and ranged from 96-209 cm, 3-5, 102-213 cm, 23-56 cm and 1.6-2.8cmfor plant height at first branch, number of verticals/hill, canopy diameter(cm), root length(cm) and stem girth(cm) respectively (Table 2).This shows that there exists sufficient variability to select high yielding cassava variety for production in these districts.

Farmers' Evaluation and preferences
In all tested districts, farmers maintain their desires in satisfying different cassava varieties for foods, income generation and socio-cultural value that farmers preserve.In this study, some farmers prefer more early-maturing varieties instead of late-maturing varieties to solve their seasonal food shortage.However, farmers express some contrary needs and make different choices as food and market importance.In all, most of tested farmers appreciate all varieties for which the harvesting coincided with the period of dry season in tested districts.During the dry season, there is seasonal food shortage in all districts when other crops are not in the field.Thus, these technologies fill a seasonal food shortage and increase cassava market price in all tested districts.This strategy of synchronizing the harvesting time with the high market price enables farmers to avoid post harvest losses.On the market, price premium is given to crops with different characteristics.On cassava, palatability, root size, shape and free from disease and insect pests are important characteristics to consumers.Faye et al. (2002) reported similar results on cowpea in Senegal and found that buyers are willing to pay a premium for grain size and white skin color but discount price for other color and number of bruchid holes on the grain.The pair-wise comparison of varieties by farmers in Jimma, Agaro and Gera districts showed that variety (Qulle) took the second place in Jimma and Agaro districts and the third in Gera (Table 3).The farmer's logic behind this result is that even if the supply of different varieties in cassava enables farmers to have their needs gradually satisfied over different years, there are periods improved cassava cuttings cause scarcity.Moreover, in Jimma and Agaro districts, variety kello was selected at the first rank by its merits; had high yielder, easily adapted to different environment, resistant to disease and frost, had good stands and resistance to lodging, large numbers of verticals/hill, quality of flour for bread and "injera", and had high market value due to its good root size and color.Nevertheless, variety 45/72 was not selected by farmers in Jimma and Agaro districts due its relatively poor performance and root yield.

CONCLUSION AND RECOMMENDATION
Our present data are not yet conclusive and since there is little information on this important root crop, there is a need to investigate further other indices of evaluation.However, based on the overall results of experiments; variety Kelle is the most vigorous, easily adapted, had large number of verticals/hill and total fresh root yield in all tested environments, and thus can be safely recommended as the variety for all the tested districts.Moreover, variety Qulle is also good in Jimma and Agaro, thus, it can be only recommended for farmers who live in Jimma and Agaro.Furthermore, the growth performance of 45/72 is also good in Gera, but poor in Jimma and Agaro and this probably resulting from unfavorable climatic conditions.

Table 3 : Varieties and their rankings on the basis of pair-wise comparisons by 20 farmers each from Jimma, Agaro and Gera districts Varieties Districts
Moreover, the mean total fresh root yield of Jimma is lower than that of Agaro and Gera districts; this is probably resulting from unfavorable climatic conditions.Furthermore, the mean data, total fresh root yield of cassava is varied from 324-1060 kg/plot and its dry matter 55.3-69.4kg/plot.Based on the overall mean of evaluation criteria's, almost all farmers in all tested environments selected Kelle variety rather than Qulle and 45/72.