Horticulture and Plant Science

Parasitic Nematodes and Fusarium Wilt Of Hot Peppers (Capsicum Spp.) And Their Management Using Endospore Forming Rhizobacteria in Jimma Zone, Southwest Ethiopia

Mon, 06 Jan 2025 00:00:00 GMT

Parasitic Nematodes and Fusarium Wilt Of Hot Peppers (Capsicum Spp.) And Their Management Using Endospore Forming Rhizobacteria in Jimma Zone, Southwest Ethiopia Shiferaw Demissie Tola; Beira H. Meressa; Diriba Muleta; Fassil Assefa Hot pepper is a popular crop in Ethiopia, widely cultivated for consumption and as a significant source of income for smallholder farmers. It also contributes to the overall economy of the country. Among vegetables and spices, pepper ranks first in terms of area under cultivation and production. However, the crop's production and productivity are often constrained by wilt causing pathogens such as Fusarium wilt and root-knot nematode (RKN), particularly during certain seasons. These issues significantly limit Ethiopia's contribution to global markets. Between 2017 and 2022, a comprehensive study was conducted to investigate the occurrence and distribution of plant-parasitic nematodes infecting hot peppers. The study also evaluated the population dynamics and damage threshold of Meloidogyne incognita, assessed the reactions of hot pepper varieties to Fusarium oxysporum and M. incognita, and examined the effectiveness of endospore-forming bacteria from the pepper rhizosphere in controlling these pathogens under both in vitro and in vivo conditions. Soil and plant samples were collected from four major pepper-growing districts in the Jimma Zone. Microbial characterization was performed in the Research and Postgraduate Laboratory of the Department of Biology, while nematode processing, soil physicochemical analyses, and pot experiments were conducted at the College of Agricultural and Veterinary Medicine, Jimma University. Molecular analyses of Meloidogyne isolates were conducted at Ghent University, while those of Fusarium and bacterial isolates were performed at the Swedish University of Agricultural Sciences. Data collected during the study were analyzed using Minitab® version 19, R-4.2.1, SAS version 9.3, and Origin Pro 202. Over 83% of surveyed pepper fields were found to be infested with parasitic nematodes, and 13 nematode types were identified. Among these, Meloidogyne, Scutellonema, Rotylenchulus, Helicotylenchus, Pratylenchus, and Rotylenchus were the most prevalent, with Meloidogyne (identified as M. incognita through Nad5 gene analysis) being the most common. This represents the first report of M. incognita on pepper crops in Ethiopia. The damage potential of M. incognita was investigated through greenhouse experiments, using 13 initial population densities (Pi). The "Dinsire" variety showed a tolerance limit for total fresh weight and fruit number at xvii 0.30 and 0.18 M. incognita (g soil)-1, respectively. Results indicated a negative correlation between Pi and both plant growth and the final nematode population density (Pf). The study estimated the maximum multiplication rate (a) and maximum population density (M) of M. incognita at 8813.2 and 3420.1 M. incognita (g soil)-1, espectively. The "Dinsire" variety performed well at a Pi of fewer than 8 second-stage juveniles (J2) (g soil)−1, exceeding the field average of 6 nematodes (g soil)−1. Fusarium isolates from infected pepper samples were identified as F. oxysporum using ITS region analysis. Among these, the isolate FI1 was highly pathogenic, significantly affecting the "Mareko Fana" variety under greenhouse conditions. Of the 11 varieties tested, "Melka Dera" was resistant to FI1, while "Melka Zala" was highly susceptible, experiencing a 66% reduction in fresh root weight and a 61% reduction in fresh shoot weight. Most pepper varieties currently under production are susceptible to Fusarium wilt, underscoring the need for further screening of genotypes and the development of effective management strategies. From 48 soil samples taken from healthy pepper rhizospheres, 35 endospore-forming bacteria were identified, exhibiting multiple plant growth-promoting traits. These included phosphate solubilization (indices ranging from 2.8 to 10), indole acetic acid production (27.31–59.16 µg/ml), and chitin hydrolysis (chitinolytic indices of 1–7.5 in 20 isolates). Of these, 21 bacterial isolates reduced pathogenic Fusarium growth by 39.4–79.2%, while 12 inhibited M. incognita egg hatching by 51–96.4% and increased nematode J2 mortality by 45–98.7%. Molecular analyses identified these bacteria as Bacillus siamensis, B. velezensis, B. cereus, and Paenibacillus polymyxa. Bacillus cereus (JUBC7) and B. siamensis (JUBC12) demonstrated strong potential for producing plant growth-promoting substances and antagonizing F. oxysporum and M. incognita in vitro. Greenhouse evaluations of 12 pepper genotypes found that the "Dinsire" variety suppressed M. incognita populations, while "Bako Local" and "Dame" were highly susceptible. Co-inoculation of B. cereus and B. siamensis reduced co-infection by M. incognita and F. oxysporum by 92.6%, with B. cereus alone suppressing Fusarium infection by 90.1%. Based on these findings, the "Dinsire" variety, in combination with B. cereus and B. siamensis, is recommended as an integrated pest management strategy for fields infested with Fusarium wilt and M. incognita, pending further validation under field conditions.

Effect of Bone Char on Nodulation Capacity, growth and yield Soybean (Glycine Max L. Merr.) Grown in High P-Fixing Acidic Soils

Fri, 27 Jun 2025 00:00:00 GMT

Effect of Bone Char on Nodulation Capacity, growth and yield Soybean (Glycine Max L. Merr.) Grown in High P-Fixing Acidic Soils Mulgeta W/Michael Fita; Milkiyas Ahmed; Gezahegn Berecha Soil acidity is one of the major obstacles to soybean production in south western Ethiopia, reducing availability of phosphorus (P) which plays a crucial role in the energy-intensive process of nitrogen fixation. Increased Nodulation efficiency and N2- fixation can be achieved with optimum P application. However, Ethiopian farmers have limited capacity to purchase and apply commercial P fertilizers. The potential of animal bone- char as P fertilizer in agricultural fields has been recently recognized and yet it is not fully utilized and its role in combination with Bradyrhizobium inoculation in soybean production is poorly understood. Therefore an experiment was conducted to evaluate how bone- char application influences nodulation efficiency, nitrogen fixation and yield of soybean in P fixing acid soil. The experiment was conducted during 2023 main cropping season at Mizan Agricultural, Technical and Vocational Education Training College demonstration site. The experiment had eight treatments including bone-char, Triple super Phosphate (TSP), TSP + lime applied with and without Rhizobium inoculation (MAR 1495) which were laid out in a randomized complete block design (RCBD ) with three replications. The P sources were applied to supply 20 Kg/ha P. Data on phenological parameters, nodulation, growth and yield traits were measured and subjected to analysis of variance (ANOVA) using SAS version 9.3. Results revealed that application of Lime + TSP and bone-char with rhizobium inoculation significantly (P<0.01) influenced most of the phenological, nodulation, growth and yield parameters. As compared to the control and other treatment the tallest plant height (61.2 cm), highest number of primary b ranches per plant (11.7), highest total nodule counts per plant (47. 86 plant–1, highest effective nodules (43.5 plant-1) and highest nodule dry weight (0.76 g plant-1) was recorded from the application of Lime + TSP with inoculation and statistically similar with bone-char with rhizobium inoculation. Application of lime + TSP without inoculation resulted in reduced number of days to reach 50% flowering (55.3) and 90% physiological maturity (117.3) as compared to rhizobium treated plot. While prolonged days to attain 50% flowering (61.7) and 90% physiological maturity (125) was recorded from treatments with rhizobium inoculation. The highest grain yield (2756.33 kg ha−1), highest aboveground biomass (3985 kg ha−1), highest number of pods (40), 100 seed weight (16.23 g) and highest harvest index of soybean (0.69) were recorded from application of TSP + Lime with rhizobium inoculation which was statistically similar with bone-char application with inoculation. Partial budget analysis revealed that, the highest net benefit of (157,661.6 Birr ha-1) was obtained from the application of Bone-char with Rhizobium inoculant followed by (154,901 Birr ha-1) from application of TSP + Lime with inoculation. MRR (511.87 %) obtained from the application of bone-char with inoculation. Therefore, the overall analysis revealed that application of bone-char with rhizobium inoculation resulted in highest yield and economic benefit. For sound recommendation the experiment should be repeated at different location, over years and seasons.

Genetic Diversity of Sweet Sorghum [Sorghum bicolor (L.) Moench] Accessions from Ethiopia using Simple Sequence Repeat Markers

Thu, 27 Jun 2024 00:00:00 GMT

Genetic Diversity of Sweet Sorghum [Sorghum bicolor (L.) Moench] Accessions from Ethiopia using Simple Sequence Repeat Markers Melkamu Genet Worku; Wosene Gebreselassie; Tsegaye Getahun Sweet sorghum is a cereal crop that can grow for multiple purpose uses. Despite its global significance and potential, it faced genetic erosion, due to its low productivity and low farmers’ preferences over grain sorghum, which is not considered as one of the most important cereal crops in Ethiopia. To utilize and popularize this crop, understanding the genetic diversity and population structure is a pre-request. Therefore, this study aimed to assess the genetic diversity and population structure of 82 Ethiopian sweet sorghum accessions that represents seven geographic regions of Ethiopia using 15 simple sequence repeat markers. The study revealed a total of 116 alleles with a mean of 11.6 alleles per locus being amplified. Ten microsatellite loci were highly polymorphic with polymorphic information content (PIC) ranging from 0.75 to 0.90 and an average of 0.82. They showed high gene diversity ranged from 0.59 to 0.81 with a mean of 0.70. There was moderate genetic differentiation (FST = 0.21), showing the presence of high gene flow where 90% of the total variation was accounted for among accessions and 5% accounted for genetic variability between populations. The clustering, principal coordinate analysis (PCoA) and population structure did not cluster the studied populations into separate groups according to their geographical origin due to the presence of high gene flow (Nm = 5.033). In conclusion, from the evaluated loci the highest private alleles were observed among populations in North Wollo and Kaffa, and hence these areas can be considered hot spots for the development of improved varieties with unique traits that are well-suited to the local agricultural practices.

Effect of Planting Density of Lima Bean (Phaseolusl Lunatus L.) On The Performance and System Productivity of Maize (Zea Mays L.)-Lima Bean Intercropping In South West Ethiopia

Thu, 27 Jun 2024 00:00:00 GMT

Effect of Planting Density of Lima Bean (Phaseolusl Lunatus L.) On The Performance and System Productivity of Maize (Zea Mays L.)-Lima Bean Intercropping In South West Ethiopia Jihad Husen; Amsalu Nebiyu; Merkeb Getachew The gradual decrease in land holdings for food production is alarming over time to meet the increasing food demand of the increasing population all over the world particularly in developing nations like Ethiopia. Cultivating multiple crops together (intercropping) is one of the feasible options to maximize crop yields per unit area. The objective of this study was to determine the optimum planting density of Lima bean when intercropped with maize for greater yield and system productivity of the associated crops. The experiment was conducted at two sites (Seka and Dimtu) of Jimma zone, Southwestern Ethiopia in the 2022/23 cropping season. The experiment consisted of treatments: sole maize (T1), sole Lima bean (T2), Lima bean intra row spaced at 35cm and intercropped with maize (T3), Lima bean intra-row spaced at 50cm and intercropped with maize (T4), Lima bean intra-row spaced at 65cm and intercropped with maize (T5). The analysis of variance showed that the effects of component population densities on phenology of maize and Lima beans were statistically not significant (p>0.05) except only for days to physiological maturity (P<0.05) at Dimtu site. Intercropping treatments showed significant differences on yield performance of maize and lima bean. Among the intercropping systems lima bean intra-row spaced at 65cm and intercropped with maize gave the highest grain yield of maize (4.83 and 4.53 t ha-1), Land equivalent ratio (1.68 and 1.63), maize equivalent yield (MEY: 7.95 and 8.0 t ha-1) and lima bean equivalent yield (LBEY: 4.40 and 4.3 t ha-1) at Seka and Dimtu sites, respectively. The intercropping maize with lima bean was advantageous than sole cropping of each crop. The findings showed that intercropping maize and Lima beans provided more yield per unit area. Therefore, planting lima bean with a density 20,512ha-1 at spacing of 75*65cm could be recommended for intercropping with maize in the target areas, spacing of 75*50cm also could be recommended as an option.