Browsing by Author "Oyoo, J."
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Item Desiree: A Potato Variety for Quality Chips(KALRO, 2017) Onditi, O.J.; Karinga, J.K. ; Nderitu, S.W.K.; Nyongesa, M.; Mbiyu, W.M.; Oyoo, J.; Otieno, S.; Muthoni, J.M.; Kabira, J.N.Desiree is a short potato variety (about 0.7 metres in high) with strong erect stems, dark green medium sized leaves and rare light pink flowers.Item Dutch Robijn: A Potato Variety with Excellent Crisping and Mashing Quality(Kenya Agricultural & Livestock Research Organization, 2013) Onditi, O.J.; Karinga, J.K.; Nderitu, S.W.K.; Nyongesa, M.; Mbiyu, W.M.; Oyoo, J.; Otieno,S.; Kenya Agricultural and Livestock Research OrganizationPlant description. This is a relatively short potato variety (just about 0.8 metre in height) with strong erect stems, dark green medium sized leaves and very rare light pink flowers. Potential yield: Ranges between 20-30 t/ha (72-110 bags if packed in 110 kg bags per acre) under sufficient rainfall and recommended crop production practices.Item Effect of Yadbiovitalizer on yield of Irish Potatoes in Limuru area, Kenya(2013) Otipa, M.; Muiru, E.; Lung'aho, C.; Oyoo, J.; Otieno, S.Organic resources play dominant role in soil fertility management in the tropics through their short-term effects on nutrient supply and longer-term contribution to soil organic matter (SOM) formation. Biovitalizer herein referred to as 'YAD' is a locally manufactured organic product and is reported to be a slow release fertilizer. A field experiment was set up to investigate the effects of different applications of manure and fertilizers on the growth and fresh tuber weight of potatoes (Solanum tuberosum) in Limuru area, Kiambu County in Kenya. The treatments consisted of Diammonium phosphate (DAP)fertilizer(l8:46:0) at 500kg/ha, Farmyard manure (FYM) (I tonlha), YAD Bio Vitalizer® (750 kg/ha), Control (no fertilizer or manure applied), DAP (250 kg/ hal + FYM (500 kglha), DAP (250 kg/ha) + YAD (375 kg/ha, FYM (500 kglha) + YAD (375 kglha).Treatments of YAD alone were applied with Ecoh balance fohar feed 2 weeks after emergence and then after every other week. The test variety was Tigoni. The experiment was conducted during the short rains season in 2010 and the long rains season in 2011 and was laid out in randomized complete block design (RCBD) with three replications.Plant spacing was 75 cm between rows and 30 cm between plants .Results showed that there were significant differences in number of tubers during the short rain season of 2010 but not during the long rain season of 2011 at P:S0.05. DAP+ FYM treatment had the highest number of tubers and also the highest tuber weights in both seasons. YAD yielded the highest ware yield (5.7 tons/ha) and the lowest chatt yield( 0.2 tons/ha) during the short rains season of 2010. The experiments need to be repeated on smallholder farmers' fields where the masking effects of the residual fertilizers could be eliminated. In addition, the cost benefit ratio of different fertilizer combinations especially the use of organic fertilizers needs to be evaluated at farmers' fields so as to make the most profitable recommendations to Irish potato producers in Kenya.Item Effect of Yadbiovitalizer on Yield of Irish Potatoes In Limuru Area, Kenya(2013) Oyoo, J.; Muiru, E.; Otieno, S.; Otipa, M.; Lung'aho.; Kenya Agricultural Research Institute, National Potatoe Research Centre Tigoni P. O Box 338-00217 LimuruOrganic resources playa dominant role in soil fertility management in the tropics through their short-term effects on nutrient supply and longer-term contribution to soil organic matter (SOM) formation. YadBiovitalizer herein reffered to as 'YAD' is a locally manufactured organic product and is reported to be a slow release fertilizer. A field experiment was set up to investigate the effects of different applications of manure and fertilizers on the growth and fresh tuber weight of potatoes (Solanum tuberosum) in Limuru area, Kiambu County in Kenya. The treatments consisted of Ammonium phosphate (DAP)fertilizer(l8:46:0) at 500kg/ha, Farmyard manure (FYM) (I toniha), YAD Bio Vitalizer® (750 kg/ha), Control (no fertilizer or manure applied), DAP (250 kg! ha) + FYM (500 kg/ha), DAP (250 kg/ha) + YAD (375 kg/ha, FYM (500 kg/ha) + YAD (375 kg/ha).Treatments of YAD alone were applied with Eco balance foliar feed 2 weeks after emergence and then after every other week. The test variety was Tigoni. The experiment was conducted during the short rains season in 2010 and the long rains season in 2011 and was laid out in randomized complete block design (RCBD) with three replications. Plant spacing was 75 cm between rows and 30 cm between plants .Results showed that there were significant differences in number of tubers during the short rain season of 2010 but not during the long rain season of 2011 at P: s0.05. DAP+ FYM treatment had the highest number of tubers and also the highest tuber weights in both seasons. YAD yielded the highest ware yield (5.7 tons/ha) and the lowest chatt yield (0.2 tons/ha) during the short rains season of 2010. The experiments need to be repeated on smallholder farmers' fields where the masking effects of the residual fertilizers could be eliminated. In addition, the cost benefit ratio of different fertilizer combinations especially the use of organic fertilizers needs to be evaluated at farmers' fields so as to make the most profitable recommendations to Irish potato producers in Kenya.Item Identifying and Controlling Major Passion Fruit Diseases for Increased Yields of Quality Passion Fruits(Kenya Agricultural and Livestock Research Organization, 2017) Pole, F.N.; Oyoo, J.; Katama, C.; Otipa, M.; Otieno, S.; Sowa, M.; Kenya Agricultural and Livestock Research OrganizationPassion fruit is a key fruit produced commercially in Kenya and ranks third among the export fruits. The production of passion fruits and its growth as a profitable enterprise however, depends on the maximum utilization of the factors of production while reducing costs. One of the major challenges encountered by passion fruit farmers is the incidences of diseases. These can reduce yields of fruits by upto 90% or lead to total crop failure. Identification of the disease and controlling them at their initials stages is a sure way of increasing yields of quality fruits that will compete effectively in the market with fruits from other areas.Item Kenya Baraka: A Potato Variety with Good Chipping and Mashing Qualities(Kenya Agricultural and Livestock Research Orgnaization, 2017) Onditi, O.J.; Karinga, J.K.; Nderitu, S.W.K.; Nyongesa, M.; Mbiyu, W.M.; Oyoo, J.; Otieno, S.; Muthoni, J.N.; Kabira, J.N.; Kenya Agricultural and Livestock Research OrgnaizationKenya Baraka is a medium sized potato plant with strong erect-stems, green medium-sized leaves and rare white flowers. The variety produces a vigorous crop with good ground cover.Item Kenya Mavuno: A High Yielding Late Blight Tolerant Potato Variety With Good Cooking and Processing Qualities(Kenya Agricultural & Livestock Research Organization (KALRO), 2017) Onditi, O.J.; Karinga, J.K.; Nderitu, S.W.K.; Nyongesa, M.; Mbiyu,W.M.; Oyoo, J.; Otieno, S.; Muthoni, J.M.; Kabira, J.N.; Kenya Agricultural & Livestock Research Organization (KALRO)Kenya Mavuno is a tall potato plant attaining a plant height of about 1 metre. It has strong semi erect stems, green medium sized leaves and abundant white flowers with regular flowering habit. The variety produces a vigorous crop with good ground cover.Ranges from 20-30 t/ha (72-110 bags of 110 kg per acre) under sufficient rainfall and recommended crop production ractices.Item Kenya Sifa: A High Yielding Late Blight Tolerant Potato Variety with Good Cooking and Processing Qualities(Kenya Agricultural and Livestock Research Organization, 2017) Onditi, O.J.; Karinga, J.K.; Nderitu, S.W.K.; Nyongesa, M.; Mbiyu, W.M.; Oyoo, J.; Otieno, S.; Muthoni, J.M.; Kabira, J.N.; Kenya Agricultural and Livestock Research OrganizationThis is a very tall potato variety (slightly above 1metre). It has strong erect stems, dark green broad leaves and slightly abundant light purple flowers with regular flowering habit. The variety produces a vigorous crop with good ground cover. Ranges between 20-30 t/ha (72-110 bags of 110 kg per acre) under sufficient rainfall and recommended crop production practices.Item Kerr’s Pink: An Early Maturing Variety with Good Cooking and Processing Qualities(Kenya Agricultural and Livestock Research Organization, 2017) Onditi, O.J.; Karinga, J.K.; Nderitu, S.W.K.; Nyongesa, M.; Mbiyu, W.M.; Oyoo, J.; Kenya Agricultural and Livestock Research OrganizationThis is a relatively short potato variety, which is (approximately 0.5 metres with thick to medium stem, dark green leaves and white flowers.Ranges between 25-30 t/ha (90-110 bags of 110 kg per acre) under sufficient rainfall and recommended crop production practices.Item Micropropagation of Different Potato Cultivars in Upscaling Seed Potato Programme in Kenya(2013) Otieno, S.; Muthoni, J.; Lung'aho, C.; Mbiyu, M.; Oyoo, J.; Onditi, J.; Nyongesa, M.; Kabira, J.; Kenya Agricultural Research Institute - National Potato Research Centre,Scarcity of good quality seed is a major constraint in potato (Solanum tuberosum) production coupled by high expensive gelling agent used in the micropropagation to produce clean pre-basic seed in the country. A study was set out to compare the performance of liquid and solid media in potato micropropagation using 10 potato cultivars. Sections of potato plantlet containing one node were aseptically inoculated at 5 nodes/kilner jar and incubated for four weeks at a light intensity of 3000 lux for 16 hours photoperiod at 20 CC. The culture media consisted of Murashige and Skoog (MS) media supplemented with different growth regulator combinations of 0.01 mg/l GA3 and 0.001 mg/l kinetin. The procedures were repeated thrice after inoculation to remove shoots from the culture vessels to divide into sections containing several nodes which were inoculated onto fresh medium and repeated every three weeks for three months. The experiment was laid out as a two-factor randomized complete block design replicated four times and was repeated three times. Results showed that there was no difference (P≤ 0.05) between the liquid and the solid media regardless of the type of growth regulator used for the parameters shoot length, number of roots and number of nodes. Solid media was the best for development of complete plantlets and multiplication from meristem tips while liquid media supplemented with 0.01 mg/l GA3 and 0.001 mg/l kinetin for sub-culturing produced plantlets with the highest vigour with respect to shoot height, root length and number of nodes. There was variability of the cultivars in their response to the micropropagation media studied suggesting that there is need to develop a cheap micropropagation protocol that may be suitable for most Kenyan potato cultivars.Item Minimizing Fungicides by Alternating Formulations and Intervals to Improve Potato Blight Management and Farm Returns(African Crop Science Journal, 2023-04-01) Kilonzi, J.; Nyongesa, M.; Pwaipwai, P.; Oyoo, J.; Mafurah, J.; Kenya Agricultural and Livestock Research Organization ; Egerton UniversityLate blight (Phytophthora infestans) is one of the most devastating and economic disease impacting both ware and the seed potato industry. The disease causes huge crop losses, and its management attracts heavy expenses. Efficacy successes in chemical management, as opposed to biofungicides, has resulted in the development of a number of fungicide formulations to counter emergence of chemically insensitive P. infestans strains. The objective of this study was to evaluate the efficacy and cost-benefits of applying different fungicides in alternate; while varying the spray intervals to manage potato blight and improve on net farm returns. A survey was conducted in Nyandarua County in Kenya, using a structured questionnaire, administered to potato farmers. Milraz®(Propineb 700 g kg-1+ Cymoxanil 60 g kg-1), Ridomil®(Metalaxyl 4%+ mancozeb 64%) and Mistress 72®(Cynamoxil 4%+ Mancozeb 64%) were used in vitro and field experiments. Plated pea agar and detached leaflets were amended with the fungicides at concentrations of 0, 35, 70 and 100% of the manufacturers recommended rate before inoculating with P. infestans. In the field experiment, the fungicides were applied at intervals of 7, 14 and 21 days spray as single, two or three fungicides in alternations. Results showed that, mycelial and blight lesion growth was curtailed by concentrations of 70 and 100%; while 35% concentration of the fungicides reduced mycelial growth and lesion size by 53 and 2%, respectively. In the field experiment, there were no yield and AUDPC differences (P< 0.05) among the fungicides and their combinations. However, spraying the fungicides at weekly and bi-weekly intervals gave the highest yields of 17.65 and 16.4 t ha-1, compared to tri-weekly and unprotected plots that recorded 7.93 and 0.43 t ha-1, respectively. In addition, application of triple fungicides in alternation reduced late blight severity by 51%; while application of two fungicides in alternation reduced severity by 39% compared to single fungicide application (21%) on average. Maximum net benefit ratio was observed on plots protected using three fungicides (31.58); followed by two fungicides applications (26.81) applied biweekly in alternate relative to single fungicide applied weekly.Item Simple Tips to Achieve Proper Seed and Ware Potato Storage(Kenya Agricultural & Livestock Research Organization, (KALRO), 2017) Otieno, S.; Kipkoech, D.; Onditi, J.O.; Mbiyu, M.; Oyoo, J.; Nyongesa, M.; Kenya Agricultural and Livestock Research OrganizationTo ensure long shelf-life of ware potatoes, tubers need to be stored in crates or pilled in a cool dry place to ensure regular supply during demand and/or attract high prices.
