Wassu Mohammed

Nutritional and chemical properties of fermented food of wild and cultivated genotypes of enset (Ensete ventricosum)

The multipurpose crop enset (Ensete ventricosum) has been traditionally cultivated in Ethiopia since ancient times. The main food product is the starch-rich fermented kocho made from the pseudostem and corm. There are many vegetatively propagated landraces utilised by farmers, but no concisions breeding have taken place, and there are requests for improved cultivars. There are also populations of wild ensets which propagate sexually, and the variation in characteristics among the wild is not studied. We suggest investigating the variation among the wild, in order utilise the most proper combinations of parent plants when breeding for different purposes. We analysed kocho, after 30 and 90days of fermentation, from three wild genotypes and three cultivars, to compare how and how much they differ in components and perceived food quality. The three cultivars scored generally higher than all the three wild genotypes for protein, fat, sugar and minerals, while the wild had larger fraction of starch. On average, panellists rated all the cultivated significantly higher than all the wild regarding the investigated characteristics (colour, texture, taste and overall). However, there were nine out of 25 panellists who rated at least one wild genotype higher or equal to at least one cultivar regarding taste, showing that people can be open for unfamiliar kocho. Therefore, we conclude that further investigations of the variation among wild plants should be done, aiming to get a larger gene pool with improved characteristics as e.g. disease tolerance or superior mineral uptake; by careful selection of parent plants, desired combinations can be achieved.

Genetic Analysis for Fruit Yield and Quality Attributes in Some Processing and Fresh Market Tomato Genotypes

ABSTRACT Higher demands for improved fruit yield and processing qualities for Tomato (Solanum lycopersicum L.) could be met through heterosis breeding. It is important to identify the parental line combination performing better for economically important quality traits. The experiment was composed of seven tomato inbred lines (two processing and five fresh market) and 21 F1 hybrids produced by crossing of them in a 7 × 7 half-diallel fashion. The nature and type of gene actions were analyzed to determine how they were involved in inheritance of fruit per plant, yield per plant, average fruit weight, total soluble solids, fruit juice pH, titratable acidity, sugar acid ratio, fruit juice content, shape index, and pericarp thickness. Most characters were predominantly controlled by nonadditive gene actions. Employing hybrid breeding for improving characters could be effective. The crosses ‘Metadel × Marglobe’, ‘Bishola × CLN2037E’, ‘Roma VF × ARP Tomato d2’, ‘Roma VF × CLN2037E’, ‘ARP Tomato d2 × Marglobe’, and ‘Eshete × CLN2037E’ showed positive and highly significant specific combining ability (SCA) effects for number of fruit per plant and fruit yield per plant. This indicated that the crosses could be used for developing high-yielding varieties. The crosses ‘Metadel × Roma VF’, ‘Bishola × Roma VF’, ‘Roma VF × Eshete’, and ‘ARP Tomato d2 × Marglobe’ exhibited positive, significant SCA effects for total soluble solids and negative, significant SCA effects for fruit juice pH. These crosses could be utilized as hybrids with better processing qualities. The crosses ‘Metadel × Marglobe’, ‘Bishola × Eshete’, ‘ARP Tomato d2 × CLN2037E’, and ‘Eshete × Marglobe’ exhibited positive, highly significant SCA effects for sugar-to-acid ratio, indicating that they could be used in hybridization for developing lines with better fruit flavor.

In vitro screening of potato genotypes for osmotic stress tolerance

Abstract Potato (Solanum tuberosum L.) is a cool season crop which is susceptible to both drought and heat stresses. Lack of suitable varieties of the crop adapted to drought-prone areas of the lowland tropics deprives farmers living in such areas the opportunity to produce and use the crop as a source of food and income. As a step towards developing such varieties, the present research was conducted to evaluate different potato genotypes for osmotic stress tolerance under in vitro conditions and identify drought tolerant genotypes for future field evaluation. The experiment was carried out at the Leibniz University of Hannover, Germany, by inducing osmotic stress using sorbitol at two concentrations (0.1 and 0.2 M) in the culture medium. A total of 43 genotypes collected from different sources (27 advanced clones from CIP, nine improved varieties, and seven farmers’ cultivars) were used in a completely randomized design with four replications in two rounds. Data were collected on root and shoot growth. The results revealed that the main effects of genotype, sorbitol treatment, and their interactions significantly (P < 0.01) influenced root and shoot growthrelated traits. Under osmotic stress, all the measured root and shoot growth traits were significantly correlated. The dendrogram obtained from the unweighted pair group method with arithmetic mean allowed grouping of the genotypes into tolerant, moderately tolerant, and susceptible ones to a sorbitol concentration of 0.2 M in the culture medium. Five advanced clones (CIP304350.100, CIP304405.47, CIP392745.7, CIP388676.1, and CIP388615.22) produced shoots and rooted earlier than all other genotypes, with higher root numbers, root length, shoot and root mass under osmotic stress conditions induced by sorbitol. Some of these genotypes had been previously identified as drought-tolerant under field conditions, suggesting the capacity of the in vitro evaluation method to predict drought stress tolerant genotypes. Most of the genotypes collected from Ethiopia were found to be susceptible to osmotic stress, except one farmers’ cultivar (Dadafa) and two improved varieties (Zemen and Belete). Field evaluation of the tested materials under drought conditions would confirm the capacity of osmotic stress tolerant genotypes to perform well under drought-prone conditions and the potential interest of in vitro evaluation as a pre-screening component in potato breeding programs.

Genetic Control of Inheritance of Fruit Quality Attributes in Tomato (Solanum lycopersicum)

The experiment comprised of seven tomato inbred lines (two processing and five fresh market) and 21 F1 hybrids produced by crossing of them in a 7 × 7 half diallel fashion excluding the reciprocals. The study was conducted at the Haramaya University, Ethiopia during July 2015 to June 2016 to analyze the genetics of inheritance of some physical and chemical quality traits. A randomized complete block design with three replications was used to conduct the experiment. Among the studied characters, only shape index and titratable acidity fulfilled the additive–dominance hypothesis. Therefore, non-allelic gene interaction could be involved in the inheritance of the characters which did not fit the model. The parental line Roma VF contained mostly recessive genes with increasing effects for shape index, and the parental lines Marglobe and Eshete contained mostly recessive genes with the increasing effects for titratable acidity. Therefore, employing these lines in hybridization for shape index and titratable acidity improvement could be ineffective, since the rapid increased frequency of recessive alleles which is the cause of loss of vigor could be resulted in advancing generation.

Effects of different dormancy-breaking and storage methods on seed tuber sprouting and subsequent yield of two potato (Solanum tuberosum L.) varieties

Abstract Potato is an important food and cash crop which in Ethiopia is produced two or more times in a year. However, its productivity is low owing to a number of constraints including a) limited availability of quality planting materials, and b) poor tuber sprouting due to long dormancy period of improved varieties at the time of planting. Two consecutive experiments were conducted from November 2013 to June 2014: 1) to assess the effects of gibberellic acid (GA3) and storage methods on seed tuber dormancy breakage of two potato varieties; and 2) to assess the effects of dormancy breakage treatments and storage methods on subsequent growth, yield and related traits of potato crop. The treatments in the first experiment consisted of two potato varieties (Bubu and Bate), three levels of GA3 [0, 10 and 20 parts per million (ppm)], and three storage methods [in diffused light store (DLS), in pit store (PS), and in farm-yard manure (FYM)]. The first trial was laid out as a complete randomized design with four replications and conducted at Haramaya University, Ethiopia. The second trial consisted of seed from each treatment in the first experiment, planted in randomized complete block design with three replications on a farmers’ field. The results showed that varieties, application of GA3 and storage methods as well as the interaction among the variety and treatments significantly affected tuber dormancy period, sprouting characteristics and subsequent tuber yield. When tubers were treated with 20 ppm GA3 and stored under FYM, the dormancy period was reduced from 102.5 and 52 to 36.5 and 31 days in improved and farmer’s variety, respectively. Tuber treatment with 20 ppm GA3 and stored under DLS, PS, and FYM, increased marketable tuber yield by 31.6%, 29.6%, and 33.6%, respectively for Bubu variety and by 92.5%, 78.4%, and 80.9% for Bate variety, respectively compared to non-GA3 treated tubers stored under DLS, PS, and FYM. However, tubers of improved variety Bubu treated with 20 ppm GA3 and stored under DLS produced the highest marketable tuber yield of 34.20 ton per ha. Tuber quality attributes (specific gravity, dry matter, and total starch content) were affected only due to interaction effects of variety and GA3 application with the highest values at 20 ppm GA3 for improved potato variety Bubu. In general, the research indicated that treating seed tubers with GA3 and storing under DLS, PS or FYM promoted early tuber sprouting and better tuber yield of both varieties. These results suggest that, use of GA3 treatment combined with different storage methods enhances early tuber sprouting and increases tuber yield. Nevertheless, further research should be continued to evaluate different potato varieties, GA3 treatment, and storage methods under different atmospheric conditions and production seasons.