RP-Department of Agricultural Sciences and Technology

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Gender, Environment and Population
(Wiley, 1994-01) Oniang'o, R.; Joekes, S.; Heyzer, N.
Response of meloidogyne hapla to mycorrhiza fungi inoculation on pyrethrum
(2001-12) Waceke, J. W.; Waudo, S. W.; Sikora, R.
Five arbuscular mycorrhiza fungi (AMF) isolated from pyrethrum were screened in the greenhouse for efficacy in improving pyrethrum growth and in suppressing a root-knot nematode, Meloidogyne hapla. The fungi screened were Glomus spp. (isolates LM61, ML34 and ML35), Scutellospora sp. (isolate KS74) and Gigaspora sp. (isolate LM83). A 20g mixed fungal inoculum was incorporated into sterilized sand-soil mixture before transplanting 6-week-old pyrethrum seedlings. The inoculum consisted of the growth medium, spores, external mycelia and infected root segments. The plants were inoculated with 6000 M. hapla second stage juvenile (J-2) 3 months after fungal inoculation. Dry shoot weights, fresh root weights, percent root colonization by the fungi, nematode gall indices, number of eggs and females in the root system and number of J-2 in the soil were determined at the end of the experiment, two months after nematode inoculation. Glomus LM61 and Scutellospora KS74 significantly improved top biomasses of fungus-treated and fungus-nematodetreated plants. Glomus LM61was more effective (33% top biomass increase). Glomus ML34 and ML35 and Gigaspora LM83 improved top biomasses of fungus-nematode-treated plants. Scutellospora KS74 and Glomus ML34 significantly increased fresh root weights of pyrethrum by 45% and 50%, respectively. Glomus LM61, Scutellospora KS74 and Gigaspora LM83 caused 86%, 32% and 37% nematode suppression, respectively. All the fungal isolates significantly reduced the number of females and J-2. The presence of nematodes in fungus-treated plants did not affect root colonization by the fungi except in plants treated with Glomus ML34 and ML35.
Zeldia spannata sp. n. (Nematoda: Cephalobidae) from the Mojave Desert, California
(Journal of Nematode Morphology and Systematics, 2005) Waceke, J.W.; Bumbarger, D. J.; Subbotin, S. A; Baldwin, J.G; Mundo-Ocampo, M.
Zeldia spannata sp. n. is described from the Mojave Desert, California. The new species shares with congeners a single guard process in each primary axil and asymmetrical triangular-shaped lips; it differs from them by the presence of elongate spanner-shaped, deeply bifurcate probolae (vs typically low, rounded and bicornuate). In addition, the new species has five lateral incisures (vs three in most other species of the genus), areolated lateral fields and tessellate cuticle (vs non-tessellate). Unlike some other Zeldia this new species lacks punctations. With respect to the bifurcate probolae, Z.spannata sp. n. resembles Chiloplacus or Stegelleta. Although the new species is reminiscent of some Nothacrobeles with respect to overall asymmetry, triangular shape of the lips, and the presence of tines on lips, maximum parsimony and maximum likelihood analyses of the ITS1, 5.8S and ITS2 of rRNA gene fragments from 13 taxa do not allow resolution of relationships between Zeldia species and several other cephalobid clades. The morphological characters of the new species are the basis for a broader, emended definition of the genus Zeldia, and suggest novel implications for evolution of Cephalobidae.
Impact of an exotic parasitoid on Plutella xylostella (Lepidoptera: Plutellidae) population dynamics, damage and indigenous natural enemies in Kenya
(Cambridge University Press, 2007) Lohr, B.; Kahuthia-Gathu, R.; Kariuki, C.; Obiero, J.; Gichini, G.
Diadegma semiclausum (Helle´n) (Hymenoptera: lchneumonidae), an exotic diamondback moth parasitoid, was released in two pilot areas (Werugha in Coast Region and Tharuni in Central Province) in Kenya. Fifteen month before release, observations on the diamondback moth, Plutella xylostella (Linnaeus), and local natural enemy population dynamics and pest damage were initiated in both areas and continued for three years after release. The P. xylostella population was bimodal with higher records during dry seasons. At Werugha, the peak population of P. xylostella was 16.8 per plant (October 2001); at Tharuni it was 12.8 (February 2002). Populations at Werugha declined from three months after release and decreased from 5.4 per plant (before release) to 0.8 (year 3 after release). Concurrently, average damage (1.9 to 1.5) (on a 0–5 scale), proportion of attacked plants (72 to 31%) and proportion of plants in damage group > 2 (plants with head damage) decreased (21.4 to 5.3%), while total parasitism increased from 14.4 (before) to 52.5% (year 3 after release, 90% due to D. semiclausum). At Tharuni, D. semiclausum was only recovered 3 months after release. Average populations of P. xylostella declined from 5.9 per plant (before release) to 2.4 (year 3 after release) and damage scores from 2.3 to 1.7. The proportion of plants in damage group >2 declined from 39.7 to 4.5% while overall parasitism increased from 4.2 to 40.6% (98.3% by D. semiclausum). Four species of indigenous parasitoids (Diadegma mollipla (Holmgren), Oomyzus sokolowskii (Kurdjumov), Apanteles sp. and Itoplectis sp., all primary parasitoids) were almost completely displaced by D. semiclausum. Possible reasons for the different parasitoid development between the two release areas and the displacement of the indigenous species are discussed.
Food Security in Africa: The Challenges of Researchers in the 21st Century
(Springerlink, 2007) Kung'u, J.B.
Food production in most of Sub-Saharan Africa (SSA) has not kept pace with the population increase over the past three decades. In many countries, food security remains a serious problem. It contributes both to high rates of under- and malnutrition, poorer learning in school, and lack of development in general. In Africa as a whole, food consumption exceeded domestic production by 50% in the mid-1980s and more than 30% in the mid-1990s. Food aid constitutes a major proportion of net food trade and in many countries it constitutes more than half of net imports. Despite food imports, per capita dietary energy supply (DES) remains relatively low; with about one-third of the countries having per capita DES of less than 2,000 kcal day−1 which is lower than the minimum recommended intake. Food imports to Sub-Saharan Africa rose from US11billionin1970toUS5.3 billion in 1985 contributing to increased external debt from US54billiontoUS58.8 billion during the same period. In 1998, external debt stood at US$230 billion. Since the 1980’s global recession and introduction of Structural Adjustment Programs (SAPs), Africa’s debt burden has grown from 30% of GNP to over 100% at present Agriculture in Africa is not only a vital source of food but also the prevailing way of life. An average of 70% of the population lives by farming, and 40% of all exports are earned from agricultural products. One-third of the national income in Africa is generated by agriculture. Crop production and livestock husbandry account for about half of household income. The poorest members of society are those who are most dependent on agriculture for jobs and income. On average, the poor in SSA spend 60-80% of their total income on food. Agricultural and economic growth must rise in Africa to realise basic development goals in the 21st century. Only a few countries are currently recording a positive growth in agricultural production while the majority of countries are seeing an increase in the area under agriculture. One consequence of the growth in agricultural area could be a doubling by the year 2050 of cultivated land area which will be great cost to the natural environment unless there is greater investment in agricultural management and technology on existing cropland. The scale of food imports in Africa has fostered dependence on food production in the rest of the world. Many Sub-Saharan African countries face the risk that supplies will fluctuate drastically with the rise and fall of grain reserves and prices on international markets. This paper tries to identify major challenges the African scientists must overcome in order for the African farmers to increase their agricultural production and achieve food security and sustainable economic growth in the 21st century.
The International Journal for Microbiologists and Biotechnologists working on Issues Relevant to the Tropics
(Journal of Tropical Microbiology and Biotechnology, 2007) Waseke, J.W.
Aggressiveness of fifteen isolates of Phaeoisariopsis griseola and variations in angular leaf spot symptom development in common bean were studied. The isolates were selected based on their virulence and genetic differences and represented Andean, Afro-Andean and Mesoamerican groups of P. griseola. Aggressiveness was determined based on length of incubation period, rate of lesion expansion, lesion size and density, rate of sporulation, disease severity and area under disease progress curve (AUDPC). There was a wide variation in aggressiveness and the type of symptoms induced by the different isolates of the pathogen. Incubation period varied significantly (P < 0.05) among isolates and ranged from six to 15 days. Mesoamerican isolates had significantly shorter incubation period than Andean and Afro-Andean isolates. Disease severity, AUDPC and rate of sporulation differed significantly (P < 0.05) among the isolates. Lesions induced by the different isolates varied significantly in size, density and rate of expansion. Mesoamerican isolates induced significantly more lesions than Andean and Afro-Andean isolates. Disease severity was negatively correlated to incubation period and positively correlated to lesion density, lesion size and rate of sporulation. The significant correlations between disease severity, AUDPC, incubation period, lesion density and rate of sporulation indicate that all these parameters are important measures of aggressiveness in P. griseola. The significant variations in aggressiveness between isolates, virulence and genetically defined groups of P. griseola indicate that this parameter can be used to characterise isolates of the pathogen. Symptoms induced by isolates of P. griseola in different bean cultivars varied extensively in size, shape and time of appearance. These variations could, however, not be attributed to any particular cultivar or isolate and can, therefore, not be used to characterise the pathogen
Improving food production using ‘best bet’ soil fertility technologies in the Central highlands of Kenya
(Springer Netherlands, 2007) Mugwe, J.; Muna, M. M.; Mugendi, D.N.; Kung'u, J.B.; Bationo, A.
Declining crop productivity is a major challenge facing smallholder farmers in central highlands of Kenya. This decline is caused by continuous cultivation of soils without adequate addition of external inputs in form of manures and fertilizers. With this background, an on-station trial was initiated at Embu in 1992 to evaluate the feasibility of using two leguminous shrubs; Calliandra calothyrsus and Leucaena leucocephala for improving food production. In 2000, an off-station farmers’ participatory trial aimed at offering farmers soil enhancing technologies for replenishing soil fertility was established in Meru South District. The results from the Embu on-station trial indicate that, over the 11 years of study, calliandra and leucaena biomass transfer with half recommended rate of inorganic fertilizer treatments gave the best average maize grain yields of 3.3 Mg ha-1. Treatment where calliandra was alley cropped with maize but the prunings removed recorded the lowest maize yield of 1.2 Mg ha-1. Treatments with calliandra and leucana biomass transfer had similar yields but treatments that were alley cropped with leucaena did better than those that were alley cropped with calliandra. On the other hand, results from the off-station trial in Meru South indicate that, on average, across the seven seasons, sole tithonia gave the highest maize grain yield followed closely by tithonia with half recommended rate of inorganic fertilizer with 6.4 and 6.3 Mg ha-1 respectively. Control gave the lowest yield of 2.2 Mg ha-1 across the seasons. On average, integration of organic an inorganic sources of nutrients gave higher yields compared to all the other treatments.
Intensive Subsistence Agriculture: Impacts, Challenges and Possible Interventions. Dynamic Soil, Dynamic Plant
(2007) Waceke, J.W.; Kimenju, J. W.
Invited Mini-Review: Despite comprising of 10-80% of total phosphorus (P) in soil solution, little is known of the composition, transformations and loss of dissolved organic P (DOP). Once dissolved in solution, organic P can either be mineralized into phosphate or lost in flowing waters. However, the potential for mineralization and loss depends on the chemical form of DOP. For instance, orthophosphate diesters such as RNA are known to be much more labile than compounds such as phosphonates or inositol phosphates (a subset of orthophosphate monoesters). This review highlights recent developments in characterising DOP, the mineralization and utilization of DOP by microbes and plants (largely via exocellular enzymes or organic acids), and the potential for loss in overland or subsurface flow under different landuses.
Transfer and Development of Pasteuria Penetrans.
(The Society of Nematologists, 2007-03) Kariuki, G. M.; Dickson, D. W.
Pasteuria penetrans isolate P-20 has been attributed as the cause of soil suppressiveness to peanut root-knot nematode in Florida. In this study, P. penetrans was transferred from a suppressive site to a new site and established by growing susceptible hosts to the peanut root-knot nematode during both summer and winter seasons. When two soil fumigants, 1,3-dichloropropene (1,3-D) and chloropicrin, were applied broadcast at the rate of 168 liters/ha and 263 kg/ha, respectively, the bacterium was not adversely affected by 1,3-D but was adversely affected by chloropicrin. In autumn 2005, after the harvest of the second peanut crop, the greatest number of J2 was recorded in the chloropicrin-treated plots, followed by the non-fumigated plots and 1,3-D-fumigated plots. The percentage J2 encumbered with endospores, endospores per J2 and percentage of P. penetrans-infected females were greatest in the non-fumigated plots, followed by 1,3-D- and chloropicrin-fumigated plots. This study demonstrates that P. penetrans can be transferred from a suppressive site to a new site and increased to suppressive densities against the peanut root-knot nematode.
Banana Xanthomonas wilt: a review of the disease, management strategies and future research directions
(African Journal of Biotechnology, 2007-03) Biruma, Moses; Pillay, Michael; Tripathi, Leena; Blomme, Guy; Abele, Steffen; Mwangi, Maina; Bandyopadhyay, Ranajit; Muchunguzi, Perez; Kassim, Sadik; Nyine, Moses; Turyagyenda, Laban; Eden-Green, Simon
Banana production in Eastern Africa is threatened by the presence of a new devastating bacterial disease caused by Xanthomonas vasicola pv. musacearum (formerly Xanthomonas campestris pv. musacearum). The disease has been identified in Uganda, Eastern Democratic Republic of Congo, Rwanda and Tanzania. Disease symptoms include wilting and yellowing of leaves, excretion of a yellowish bacterial ooze, premature ripening of the bunch, rotting of fruit and internal yellow discoloration of the vascular bundles. Plants are infected either by insects through the inflorescence or by soil-borne bacterial inoculum through the lower parts of the plant. Short- and long-distance transmission of the disease mainly occurs via contaminated tools and insects, though other organisms such as birds may also be involved. Although no banana cultivar with resistance to the disease has been identified as yet, it appears that certain cultivars have mechanisms to ‘escape’ the disease. Management and control of the disease involve methods that reduce the inoculum’s density and spread of the pathogen. Removal of the male bud (de-budding) has proven to be very effective in preventing the disease incidence since the male bud appears to be the primary infection site. The economic impact of banana Xanthomonas wilt is not fully understood but its impact on food security in the region is very significant. While germplasm screening for the disease is ongoing, efforts to genetically engineer resistance in some banana cultivars are also making good progress. This paper presents a review of the disease and management strategies that have been successful in curtailing its spread
Can low release numbers lead to establishment and spread of an exotic parasitoid: The case of the diamondback moth parasitoid, Diadegma semiclausum (Hellén), in East Africa
(Science Direct, 2008-06) Gichini, G.; Löhr, B.; Rossbach, A.; Nyambo, B.; Kahuthia-Gathu, R.
From 2001 onwards, Diadegma semiclausum, an exotic parasitoid of the diamondback moth, was introduced and released in Kenya, Tanzania and Uganda. Contrary to common practice where thousands of parasitoids are released, we released very low numbers, 125 females in Kenya, 160 in Uganda and 350 in Tanzania. About 2 years after this single release, the establishment and natural spread of the parasitoids was assessed in all release areas. Two methods were employed: in Kenya, a grid with equidistant points in the four cardinal directions (2–50 km) with the release area in the centre was used and collections were made 27 months after release at the predetermined points. The parasitoid was found up to a distance of 30 km from the release site. In Tanzania and Uganda, surveys were made starting from the release area following major roads. At regular intervals, fields were inspected and their position recorded with a Geographic Positioning System (GPS). The results of a field survey conducted 24 months after release indicate that in Tanzania, the parasitoid had spread >20 km from the release site while in Uganda, the spread was >30 km. Wherever D. semiclausum was collected, it was the major parasitoid species. Indigenous parasitoids collected were Oomyzus sokolowskii (Hym.: Eulophidae), Diadegma mollipla (Hym.: Ichneumonidae) and Apanteles sp. (Hym.: Braconidae). Overall parasitism and the contribution of the introduced parasitoid to the control of diamondback moth population tended to decrease with increasing distance from the release point. The introduced parasitoid had displaced the indigenous species wherever it was well established.
Overcoming Seed Dormancy in Cleome gynandra L. to Improve Germination
(Association of Official Seed Analysts, 2009) Muasya, R.M.; Simiyu, J.N; Muui, C.W; Rao, N.K.; Dulloo, M.E.
Cleome gynandra L. is a traditional semi-domesticated leafy vegetable grown in East Africa. It belongs to the family Cleomaceae. Farmers save seed from each harvest for planting in the next season. C. gynandra seeds fail to germinate when planted immediately after harvest. Studies were con ducted to determine appropriate seed treatments to overcome dormancy in freshly harvested C. gynandra seeds. Seeds were subjected to various dor mancy breaking treatments including: potassium nitrate (KN03), leaching, light, gibberellic acid (GA3) and chilling. Additional studies were carried out to determine the degree of dormancy in seeds harvested from pods at different positions on the plant. Among all treatments studied, application of GA3 at a concentration of 500 ppm resulted in the highest final germina tion. Stratification for two weeks at 5 °C and germination in dark also im proved germination significantly. While leaching had no significant effect, treatment with KN03 and light reduced germination. Seeds from lower and middle positioned siliques germinated readily compared to those from up per siliques. We suggest for commercialization of C. gynandra seed that have high potential germination, treating seeds immediately after harvest with GA3 at a concentration of 500 ppm before being packaged and sold to farmers is a possibility that can be explored.
Root rot resistance in new cassava varieties introduced to farmers in Nigeria
(Cambridge University Press, 2009-01) Mwangi, M.; Okechukwu, R. U.; Dixon, A. G. O.; Akoroda, M. O.; Bandyopadhyay, R.
In 2004 and 2005 through field trials in over 2500 locations in several agroecological zones, 40 new cassava varieties were introduced in Nigeria. The trials were managed by scientists, extension workers and farmers. The aim in introducing these new varieties was to pre-emptively manage cassava mosaic disease, to avert an imminent threat from the Ugandan strain of the pathogen and prevent damage to the Nigerian cassava economy. From these trials, 10 new varieties were selected and officially released for high root yield, high dry matter content and acceptability for food, industry and livestock. Cassava root rot is a major source of yield loss in Nigeria, especially where farmers practice late harvest because they wait for a good price from the market before harvest and sales. This paper investigated how the 40 varieties together with three old improved varieties currently in farmers' fields during the formal trials responded to root rot disease. No absolutely resistant variety was found, indicating that early harvest (9–11 months after planting) is still the best way to reduce losses from root rot. Root rot is also significantly (p ≤ 0.05) influenced by genotype and environment interaction. Most root rot was recorded in the humid forest and the least was in the Sudan savanna agroecological zone. Using a rank-sum method, the 43 varieties were separated into highly resistant, resistant, moderately resistant, moderately susceptible, susceptible and highly susceptible classes.
Assessment of genetic variation of selected spiderplant (Cleome gynandra L.) morphotypes from Western Kenya
(Academic Journals, 2009-06) Muasya, R. M.; K'Opondo, F. B. O; Rheenen, H. A.
Building capacity in plant nematology in sub – Saharan Africa: contributions by nematology initiative of east and southern Africa (NIESA)
(The journal of nematology, 2010) waseke, J.W.; Kimenju, J.W.; Sibanda, Z.; Talwana, H.
Plant nematology in sub - Saharan Africa continues to lag behind other disciplines mainly because those trained in the discipline spend a significant proportion of their time in other disciplines and lack peer support as most of the trained nematologists work on their own. Further to this, there is inadequate support from policy makers due to the perception that the nematodes are not as important as other biotic and abiotic stresses and lack of awareness by the farmers of even the existence of the nematodes. Due to this, yield losses of up to 60% on cash and food crops are common in the region. A survey conducted in 1996 by CABI Bioscience aimed at identifying sources of taxonomic expertise in nematology revealed that outside of South Africa, there were only two practicing nematode systematists in Africa. Another survey commissioned by Gatsby Charitable Foundation (GCF) in 2003 to determine capacity needs in plant nematology in East and Southern African region revealed similar findings. To address this need, GCF funded a five year regional project (2005- 2010) on capacity building in plant nematology. This project covered Kenya, Malawi, Uganda, Tanzania and Zimbabwe, and received technical support from CABI Bioscience, Rothamsted International and the University of Reading in the UK. One of the project results was the establishment of NIESA in August 2005 with the primary aim of promoting plant nematology in the region. Since its inception, four MSc and three PhD students have completed their studies. Sixty scientists from Tanzania, Kenya, Mozambique, Uganda, Zimbabwe, Malawi, Southern Sudan and Rwanda have also been trained through workshops. The initiative has also developed a plant nematology training manual; established and fully equipped six nematology laboratories in the region; developed an interactive website (http://www.africannematology.info/index.asp); established links with Nematological Society of South Africa (NSSA) and undertaken several joint research projects. The capacity building efforts by NIESA have, however, focused mainly on postgraduate and research scientists, and there is still a need for vocational training targeting extension officers, NGOs and farmer groups. An advocacy program targeting decision and policy makers is needed to convince them about the damaging effects of nematodes, and the need for increased investment on soil health. Whereas most of the nematology research conducted in the region has centered on the control and management, there is minimal work on taxonomy due to the lack of trained taxonomists. The scope needs to be broadened to cover all aspects of plant nematology and other biotic and abiotic interacting factors within the context of soil health.
A Comparative Study of Plant Species Composition of Grasslands in Saiwa Swamp National Park and Kakamega Forest, Kenya
(2010) Akwee, P.E.; Palapala, V.A.; Gweyi, Joseph Onyango
Kakamega forest is a tropical rain forest ecosystem while Saiwa Swamp National Park (SSNP) is a riverine ecosystem. A study was conducted to determine plant species diversity of the grasslands in both the ecosystems with emphasis on herbs and grass species, and the structure of the ecotones. The objective of study was to compare the plant species richness of these two ecosystems with an aim of proposing some conservation strategies. Species diversity was determined using inverse Simpson Index. The sampling sites were determined using stratified random sampling. The random quadrats (1x1M), line intercept, and nested quadrat sampling methods were used to collect data from the clear grassland. A 5x5M sampling plot was used to collect data from the bushed-grassland community of both ecosystems. All plants species present were identified and recorded. The density, frequency, foliage cover, importance value indices and relative values were calculated. Temperature and relative humidity were determined. Results clearly show that Kakamega forest grassland community had the highest species diversity of 0.9 and an abrupt ecotone compared to Saiwa National Park of species diversity of 0.8 and a blending ecotones These results confirmed that, there is great variation in species diversity in both ecosystems and discontinuity of ecotones due to influence of environmental conditions.
Differential Benefits Of Rock Phosphate (RP) By Tomato ( Lycopersicon esculentum check for this species in other resources Mill.) Plant As Affected By Nitrogen Forms And Soil Types
(Bioline International, 2010) Gweyi, Joseph Onyango; Günter, N.; Römheld, V.
Phosphorus is one of the critical elements that limit plant production, particularly in humid and semi-humid soils. For realization of African Green Revolution, use of rock phosphate (RP) by resource-poor farmers may be an alternative to more expensive water soluble phosphate (P). Utilization of RP was investigated in tomato ( Lycopersicon esculentum check for this species in other resources Mill) var; Moneymaker in minirhizotrons at Hohenheim to assess root-induced chemical changes in the rhizosphere with two soil types: - Arenosol and C-horizon of Luvisol. Additionally, field experiments were conducted at Kibwezi and Maseno (Luvisol and Ferralsol, respectively) in Kenya. All trials received RP and soluble P as source of P and nitrate and ammonium (stabilized with DMPP as nitrification inhibitor) as nitrogen sources. Ammonium treatment significantly reduced rhizosphere pH in minirhizotron treatment with Arenosol with corresponding increase in shoot P content (but with significant negative shoot biomass accumulation), while rhizoplane pH differed significantly from rhizosphere pH treatment with C-horizon of Luvisol and there was no RP benefit to plant. The buffer capacity of the Luvisol was quite high and the pH 2mm away from rhizoplane was similar to that of bulk soil. However, minimal NO3- additions to ammonium treatment significantly improved biomass production in both soils. In both rhizobox experiments, NO3- led to rhizosphere alkalinization. Both shoot and fruit biomass was enhanced by RP application at Maseno, while RP had a negative effect on tomato plant production at Kibwezi. Therefore, role of RP on improved tomato yield at Maseno may partly be attributed to secondary factors other than P, viz; alleviation of aluminium rhizotoxicity since the Al content was significantly reduced by RP treatment, while RP may have led to partial alkalinization at specific root/rhizoplane, leading to Zinc deficiency at Kibwezi site. The application of rock phosphate in addition to acidifying nitrogenous fertilizer with consideration to soil types has potential of improving crop production and phosphate capital of resource-poor farmers.
Longevity of Bean (Phase olusvulgaris) Seeds Stored at Locations Varying in Temperature and Relative Humidity
(Moi University Press, 2010) Rugut, Eliud; Muasya, Reuben; Gohole, Linnet
Seed is an important input in agricultural production and its quality is essential in determining maximum potential crop yield. Conditions under which the seed is stored is often a major cause of poor seed quality. The combined effect of high moisture content and storage temperature are critical factors that affect storage potential and eventual quality of seed at planting time. The aim of this study was to determine effects of temperature and relative humidity on the viability of bean seeds stored under stockists store conditions. Mwitemania- GLP 92 bean seeds were stored by stockists at different locations varying in temperature and relative humidity. The same seeds were also stored under controlled temperature of -20°C and relative humidity of 50% at the Seed Science laboratory, Chepkoilel Campus. Mean temperature and relative humidity of the three stockists stores in each town were recorded daily and their means calculated. The bean seeds were packed in clear polythene bags and stored by stockists in Bungoma, Nyeri, Nairobi and Mombasa. Viability and vigour tests were performed at zero days of storage and after every 30 days for 12 months of storage. Data was subjected to Analysis of Variance (ANOVA) and means separated by Least Significant Difference (LSD) at P<0.05. Results showed that the seeds stored under controlled conditions at Chepkoilel Campus maintained their quality for 12 months while the seeds stored by stockists in Mombasa with recorded mean maximum temperature and relative humidity of 30.8°C and 80.1 % respectively showed a rapid decrease in viability which went below the accepted levels after one month of storage. In Nyeri, Bungoma and Nairobi, seeds remained viable above the accepted levels for 6 months. It was concluded that longevity of seeds depends on the ambient temperature and relative humidity at the stockists stores.
Macropropagation Technology to Produce Banana Seedlings Free from Plant Parasitic Nematodes in Central and Eastern Kenya
(aGRO, 2011) Njau, N.; Mwangi, M.; Kahuthia-Gathu, R.; Mbaka, J.; Muasya, R.
Banana (Musa spp) is one of the most important food crops contributing to food "security for majority small holders in Kenya. However, banana production has not reached its full potential' due to pest infestation. Plan parasitic nematodes (PPN) are maj or pests ofbanana mostly transmitted to new fields through infested, planting material. Macropropagation is a technology that can produce affordable seedlings. A survey was carried out in Eastern and Central regions in Kenya to determine important banana pests and diseases PPN was found in more than 20% of the farms surveyed. These were Radopholus spp. and Pratylenchus spp. Macropropagation nurseries were set up in Meru Central, lmenti South Mitunguu, Imenti south Tharene, Kerugoya, Embu and Mathioya districts and in Kenyatta University to evaluate, the efficiency of Macropropagation 'technology to produce banana seedlings free fromPPN. Selection of corms was done using an established protocol. Five functional roots were selected randomly from 10 corms of each variety used for propagation and scored for nematode damage. Seedlings that arose from the nurseries were monitored and tested for presence of PPN. Results showed that 92% farmers in the area surveyed use suckers as, the major propagating material thus increasing the chances of disseminating the pest, Furthermore less than 15% of the farmers treat their suckers prior to planting. The root: scored showed that Kampala, Sweet banana, Uganda green and Cavendish banana varieties had 19%,23 %,36% and 46% damage respectively, indicating more damage in Cavendish varieties which are used for commercial purposes 100%, of the seedlings showed no symptoms of infestation. No PPN were extracted from any of the roots. Macropropagation technique can be used to produce banana seedlings that are free of plant parasitic nematodes. This technology should be taught to farmers to improve banana productivity and the life of plantations.
Mineral Deficiency in Production of Banana Seedlings
(International E-Conference on Agricultural Biosciences, 2011) Njau, N.; Mwangl, M.; Kahuthia-Gathu, R.; Kori, N.; Muasya, R.
Banana (Musa spp.) is one of the most important fruits for food security and income. It fruits all year round thus providing a continuous supply of food. Bananas require nutrients so as to give high yields and good quality fruits. They require nutrients high in Nitrogen (N) and Potassium (K). K is important for promoting early shooting and reduces the amount of time the fruit takes to mature while improving size of the fingers and quality. Therefore, soil fertility must be maintained by continuously replenishing the soil with nutrients in form of either organic or inorganic nutrients. Nitrogen deficiency is shown by small and pale green leaves. Potassium deficiency is shown by the leaves turning brown, curling and drying up starting with the older leaves, the midrib breaks at two thirds of the stem. Nutrients are important in all stages of growth of

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