An update of sweet potato viral disease incidence and spread in Ethiopia

Sweet potato (Ipomoea batatas (L.) Lam.) is an important root crop for poor farmers in developing countries. Since the late 1980s, viral diseases have increasingly become a threat to sweet potato production in Ethiopia. This review paper presents the role of sweet potato production for ensuring food security, the level of sweet potato virus research, including the types of viral species identified and their current level of incidences in Ethiopia. Sweet potato feathery mottle virus (SPFMV), Sweet potato chlorotic stunt virus (SPCSV), Sweet potato virus 2 (SPV2), Sweet potato virus G (SPVG), and Cucumber mosaic virus (CMV) were reported in Ethiopia, where the first two are the most common and exist at high incidences. In addition, this paper discusses the virus vectors, virus transmission methods to new farms, factors exacerbating the rate of viral incidence and the methods used to reduce the incidences. Moreover, it highlights methods of sweet potato viruses’ detection and cleaning of infected materials in use and the challenges encountered towards the efficient utilization of the methods. Finally, we suggest major intervention techniques that will integrate all key players in managing the impact of the virus on sweet potato production to improve productivity and ensuring food security in Ethiopia. The findings obtained from this review could be an input for the current research on sweet potato improvement (both planting materials and routines) in Ethiopia.publishedVersio

Variability, heritability and genetic advance in sugarcane (Saccharum spp. hybrid) genotypes

AbstractThe study was carried out with the aim of estimating variability, heritability, and genetic advance for 196 sugarcane genotypes. Results of the analysis of variance identified a very highly significant variation among the genotypes in all the traits evaluated. Except for stalk length and single cane weight, all of the traits’ lowest and highest mean values were present within the genotypes from fuzz, indicating the wide ranges of variability within the genotypes. Except for single cane weight, the highest mean values for all the traits were seen within the genotypes of fuzz, implying greater genetic potential for the genotypes of fuzz for these traits. The number of sprouted buds, number of tillers, and cane yield had high genotypic and phenotypic coefficients of variation, heritability, and genetic advance as a percentage of the mean. This indicates the presence of high levels of heritable genetic variations for these traits, implying that these traits could be improved through phenotypic selection. The number of stalks, plant height, stalk length, internode length, stalk diameter, single cane weight, brix, and purity had high to moderate heritability with moderate to low genetic advance as percentages of the means. This indicates that the phenotypic expression of these traits is highly influenced by non-genetic factors. Thus, it could be difficult to directly improve these traits via phenotypic selection; instead, efforts should be directed toward better management practices. This study presents the first evidence for the existence of variability in the newly introduced sugarcane genotypes that should be exploited

Genetic diversity of sugarcane (Saccharum spp.) genotypes based on agro-morphological and biochemical traits

AbstractKnowledge of genetic diversity is essential for the effective planning of breeding experiments and successful development of an improved variety. Therefore, this study was aimed at assessing the genetic diversity of 196 sugarcane genotypes. The experiment was conducted in a parietal-balanced lattice design with two replications. Data on 13 agromorphological and five biochemical traits were collected and analyzed using both univariate and multivariate statistical methods. Cluster analysis grouped the entire sugarcane genotypes into five, two, and six distinct clusters, respectively, based on agro-morphological, and biochemical traits, and their combinations. The highest intercluster distances were found in clusters three and five from a study of agro-morphological traits and clusters four and five from a combination of agro-morphological, and biochemical traits. The highest intercluster distance values indicate the presence of substantial genetic variability between the genotypes of the pairing clusters, due to highly contrasting and complementing traits as demonstrated by cluster mean analysis, notably for cane and sugar yields. This suggests that cultivars with greater cane and sugar yields can be created by hybridization between the genotypes of the two divergent clusters. Cluster mean analysis based on agro-morphological and biochemical traits revealed that Cluster One genotypes have the highest average sugar yield, suggesting that these genotypes are ideal for selection and hybridization to enhance this particular trait. Generally, the evaluated genotypes have potential diversity in their agro-morphological and biochemical traits, which could be exploited. Additionally, a study of the molecular genetic diversity of these genotypes is required to complement the results of this study

Agronomic Potential of Avocado-Seed Biochar in Comparison with Other Locally Available Biochar Types: A First-Hand Report from Ethiopia

Biochar is a promising option for improving soil fertility and agricultural productivity. The potential of biochar for specific purposes depends on its physical and chemical characteristics. The avocado seed is widely available as a leftover after the fleshy part is used for food and as a byproduct of avocado-oil producing agro-industries in Ethiopia. Its potential as a biochar for an agronomic purpose has not been studied. The objective of this study was to compare the agronomic potential of avocado-seed biochar (ASB) type in comparison to other biochar types produced from locally available feedstocks at two selected pyrolysis temperatures (450 and 550°C). It was identified that on a mass-base, the produced biochar yields were in a range of 29.68 to 47.45%, higher for ASB pyrolyzed at 450°C. The scanned images of the biochar types showed a remarkable surface morphology for bamboo biochar (BB) and ASB. The bulk density of the biochars were in the range of 0.21 to 0.49 g/mL. The highest volatile matter was measured for BB-450°C, fixed carbon for BB-550°C, and ash content for BB-450°C. The mean pH values were in the range of 9.1 to 11.3. The ASB-450 and 550°C exhibited higher nutrient content. The highest cation exchange capacity (CEC) was recorded for ASB-450°C; organic carbon (OC) for corncob biochar (CCB) was followed by ASB-450 and 550°C. The calcium carbonate (CaCO3) content of ASB-550°C was the second-highest value next to coffee husk biochar (CHB). In this study, ASB and BB were found to have important qualities for improving degraded agricultural soils in terms of soil acidity, nutrient content, and soil fertility. Therefore, ASB-450°C and BB-450°C can be suggested to be promising candidates for reclaiming acid-soils and for improving nutrient-depleted infertile soils into agriculturally productive soils

Variability, heritability and genetic advance in sugarcane (<i>Saccharum</i> spp. hybrid) genotypes

The study was carried out with the aim of estimating variability, heritability, and genetic advance for 196 sugarcane genotypes. Results of the analysis of variance identified a very highly significant variation among the genotypes in all the traits evaluated. Except for stalk length and single cane weight, all of the traits’ lowest and highest mean values were present within the genotypes from fuzz, indicating the wide ranges of variability within the genotypes. Except for single cane weight, the highest mean values for all the traits were seen within the genotypes of fuzz, implying greater genetic potential for the genotypes of fuzz for these traits. The number of sprouted buds, number of tillers, and cane yield had high genotypic and phenotypic coefficients of variation, heritability, and genetic advance as a percentage of the mean. This indicates the presence of high levels of heritable genetic variations for these traits, implying that these traits could be improved through phenotypic selection. The number of stalks, plant height, stalk length, internode length, stalk diameter, single cane weight, brix, and purity had high to moderate heritability with moderate to low genetic advance as percentages of the means. This indicates that the phenotypic expression of these traits is highly influenced by non-genetic factors. Thus, it could be difficult to directly improve these traits via phenotypic selection; instead, efforts should be directed toward better management practices. This study presents the first evidence for the existence of variability in the newly introduced sugarcane genotypes that should be exploited.</p

An update of sweet potato viral disease incidence and spread in Ethiopia

Sweet potato (Ipomoea batatas (L.) Lam.) is an important root crop for poor farmers in developing countries. Since the late 1980s, viral diseases have increasingly become a threat to sweet potato production in Ethiopia. This review paper presents the role of sweet potato production for ensuring food security, the level of sweet potato virus research, including the types of viral species identified and their current level of incidences in Ethiopia. Sweet potato feathery mottle virus (SPFMV), Sweet potato chlorotic stunt virus (SPCSV), Sweet potato virus 2 (SPV2), Sweet potato virus G (SPVG), and Cucumber mosaic virus (CMV) were reported in Ethiopia, where the first two are the most common and exist at high incidences. In addition, this paper discusses the virus vectors, virus transmission methods to new farms, factors exacerbating the rate of viral incidence and the methods used to reduce the incidences. Moreover, it highlights methods of sweet potato viruses’ detection and cleaning of infected materials in use and the challenges encountered towards the efficient utilization of the methods. Finally, we suggest major intervention techniques that will integrate all key players in managing the impact of the virus on sweet potato production to improve productivity and ensuring food security in Ethiopia. The findings obtained from this review could be an input for the current research on sweet potato improvement (both planting materials and routines) in Ethiopia

Effect of Moisture Stress on Physiological and Yield Responses of Common Bean Varieties at Lath House Condition, Hawassa University, Southern Ethiopia

Common bean is one of the most traditional foods, with social and economic importance, and is suitable for food security due to its short growing cycle and adaptability to different cropping systems. However, various constraints like biotic and abiotic factors reported for the low productivity of the crop. Therefore, the study was designed to identify the common bean varieties’ response on physiological properties and yield performance under different irrigation intervals in Lath House condition at Hawassa University, Ethiopia, from June, 2020, to September, 2020. The experiment was laid out in a completely randomized design with a factorial combination of seven common bean varieties (Awash-1, Awash-2, Dursitu, Fedis, Gofta, Nasir, and Tinike) and three moisture levels, eight day irrigation interval, four day irrigation interval, and daily watering with three replication. There was a significant main and interaction effects among the measured parameters. From those significantly affected parameters, the highest stomata numbers (25) were recorded from the Dursitu variety with a daily irrigation interval. The longest stomata aperture was observed with Gofta (133.76 nm) and Fedis varieties (131.13 nm) to daily irrigation and four day irrigation intervals, respectively. A wider stomata aperture was found in the Awash-1(12.6 nm) variety on a daily irrigation interval, and maximum stomata conductance (193.67) was obtained in the Tinike variety treated with a four day irrigation interval. The maximum relative leaf moisture content (96%) was found on the Awash-1 variety at a four day irrigation interval. Maximum water use efficiency was obtained from the Awash-1 (3.95) variety, which is an insignificant variation with the Awash-2 (3.85) and Gofta varieties (3.85) at a four day irrigation interval. Among the varieties, the highest photosynthesis rate (10.43 μmol·m−2·s−1) and transpiration rate (5.42 mmol·m−2·s−1) were obtained in the Gofta variety treated by a four day irrigation interval. In the photosynthetic pigment analysis, the highest leaf chl-a, chl-b, and chl-a + b concentration was recorded at 2.4 μg/ml, 1.53 g/ml, and 3.93 μg/ml, respectively, in the Gofta variety irrigated at a four days interval. The highest (0.586) chlorophyll fluorescence was obtained in the eight day irrigation interval. The highest proline content was found from the Awash-1 (0.78) variety regarding to drought stress condition. The highest pods plant−1 (9) and seed pod−1 (5) was found in the Awash-2 and Awash-1 varieties, respectively, at a four days irrigation interval and the highest main effect of 100 SW (39.48 g), (28.6 g) was found in the Fedis variety and at a four day irrigating interval, respectively. The maximum yield was obtained from the varieties Awash-1 (7.8 g plant−1) and Gofta (7.36 g plant−1) with a four day irrigated interval and they are also superior at drought condition and Awash-2 varieties are enhanced at waterlogging condition as compared to the other varieties

Study on characters associations and path coefficient analysis for quantitative traits of amaranth genotypes from Ethiopia

Abstract Selection based on yield alone may not be effective for yield improvement in plant breeding programs. Thus, in order to progress the genetic gains during selection, yield should be considered along with potential yield contributing traits. The objective of this study was to improve the genotype of amaranth and increase the effectiveness of selection in the program by identifying the correlation and path coefficients between yield and its relevant attributes. On 120 genotypes of amaranth planted during two growing seasons in 2020 and 2021, the study was carried out using an alpha lattice design with two replications. The results revealed significant positive phenotypic and genotypic associations on leaf yield, with leaf area, leaf breadth, branch number, leaf number, plant height at flowering, and grain yield all having positive direct effects. Similar strong positive phenotypic and genotypic relationships were found for grain yield and grain sink filling rates. Using path coefficient analysis, the direct and indirect effects of yield-related traits on yield were also determined. In addition to having a strong direct impact on grain output, the grain sink filling rates showed both phenotypic and genotypic evidence of substantial positive relationships with grain yield. It was further suggested that leaf yield in amaranth genotypes may increase through the indirect selection of plant height at maturity, leaf length, and terminal inflorescence lateral length, which showed such significant indirect influences, mostly through leaf area, days to maturity, and days to emergence, which displayed such strong indirect effects, primarily through plant height at flowering. This study consequently shows the need for traits with significant positive indirect impacts via leaf area to be considered indirect selection criteria for improving leaf yield in amaranth genotypes. The grain sink filling rate also significantly improved grain yield indirectly at both the phenotypic and genotypic levels, mainly via days to flowering and leaf yield. This demonstrated that selection that mainly targeted days to flowering, leaf yield, and grain sink filling rate would ultimately boost the grain yield in amaranth genotypes