Browsing by Author "Isutsa, D.K."

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Asynchronous Learning Demonstration
(2022-10-01) Isutsa, D.K.
Blended Learning Demonstration
(2022-07-01) Isutsa, D.K.
Chuka University Humanities Students packed in an in-person classroom
(2022-10-01) Isutsa, D.K.
Chuka University staff and students exhibiting digital media
(2022-08-01) Isutsa, D.K.
Effect of Nitrogen, Mulch and Gibberellic Acid on Quality of Multi-Purpose Pumpkin (Cucurbita moschata Duchesne) Fruits
(Infogain Publication, 2021) Mwaura, M.M; Isutsa, D.K.; Munyiri, S.W.; ; ;
Emergence of multi-purpose pumpkin (Cucurbita moschata Duchesne) as an African indigenous vegetable is attracting great attention. This is due to its adaptation to a wide range of climates and high-yielding potential. Sub-optimal pre- and post-harvest factors have greatly contributed to low returns to the farmers through poor yields and high post-harvest loss of pumpkins. There is therefore need to determine the optimal pre- and post-harvest inputs which will provide nutritious pumpkin fruits to consumers. To contribute in solving this challenge, knowledge on the effect of nitrogen fertilizer, mulch and gibberellic acid on the fruit size, flesh thickness and firmness of multipurpose pumpkin (Cucurbita moschata Duchesne) is very important. A field experiment was therefore set at the Chuka University farm for two seasons between January 2019 and July 2020.It was arranged in a split-plot in randomized complete block design and replicated three times. Nitrogen (CAN) (0, 50, 100 and 150 kg N/ha), mulch (no mulch, black-painted and unpainted rice straws) and gibberellic acid (GA3) (0 mg/L, 40 mg/L and 80 mg/L) were assigned to the main plots, split plots and sub-plots respectively. Data was collected fortnightly from the fourth week after emergence. Data values were subjected to analysis of variance using the SAS software and means separated using least significant difference. Application of N fertilizer was significant on fruit size (0.013) during the second season, flesh thickness during the first and the second season (0.002and 0.04respectively) and fruit firmness of 0.02 upper and 0.009 lower during the second season. Application of N at150kg N/ha and black-painted mulch resulted to fruit size of 2172 cm 2 and 2199 cm 2 respectivelyand flesh thickness of 3.387cm and 3.856cm respectively which was higher than the other treatments. The effect of GA3 on fruit size, flesh thickness and firmness of multipurpose pumpkins was insignificant during both seasons. These results show that application of N at 150kg N/ha and black painted mulch would give the best fruit quality to the farmers while application of GA3 may not necessarily result to beneficial returns.
Enhancing Preharvest Physiology of Multi-Purpose Pumpkin Using Combined Nitrogen, Mulch and Gibberellic Acid
(African Journal of Horticultural Science, 2022) Isutsa, D.K.; Mwaura, M.M.
In recent times, it has become apparent that multi-purpose pumpkin (Cucurbita moschata Duch.) is a very important crop since its leaves, fruits and seeds can be eaten as vegetables, snacks and blended dishes to boost household food and nutritional security. However, it is regarded as a low value crop, leading to poor cultivation, comprehension of preharvest physiological behaviour, and maximization of productivity in Kenya. Consequently, a study was conducted to assess the effects of combined nitrogen, mulch and gibberellic acid (GA3) in enhancing its preharvest physiology of pumpkin. Four N rates of 0, 50, 100 and 150 kg N/ha supplied as CAN, three mulch types as none, unpainted, and black-painted rice straw, and three GA3 rates of 0, 40 and 80 mg/L were assessed. The experiment was arranged in split-split plots in randomized complete block design, replicated three times in two seasons, and each plant occupied 2 m x 2 m space. Nitrogen was applied to main plots, mulch to sub-plots, and GA3 to sub-sub plots. Pre-harvest physiological variables measured were stomatal conductance, chlorophyll, photosynthesis, and transpiration. Data values were subjected to analysis of variance using SAS Version 9.3. Separation of significant means was done using the least significant difference test at α = 0.05. Results showed that nitrogen and mulch individually and interactively did not significantly (P > 0.05) affect most pre- harvest physiological parameters. The effect of GA3 was not significant on stomatal conductance and leaf chlorophyll, but it was negative and significant on both photosynthesis and transpiration in season 1 which was drier than season 2. Based on the present results, the influence of combined nitrogen, mulch and GA3 on multi-purpose pumpkin cannot be entirely depicted by analysing preharvest physiology. Adoption and application of treatments that promote desired preharvest physiology of multi-purpose pumpkin is recommended, including 50 kg N/ha to enhance stomatal conductance and leaf chlorophyll, and unpainted rice straws to enhance leaf chlorophyll content and photosynthesis.
Evaluation of Endogenous Phytocomponents and Amino Acids Associated with Direct Somatic Embryogenesis of Coffee (Coffea arabicaL.)
(Journal of Advances in Agriculture, 2022) Mayoli, R.N.; Isutsa, D.K.; Nyende, A.B.; Mweu, C.M.; ; ;
Coffee is one of the mostimportant cropscultivated in the world for use in beverages and confectionaries. Embryogenesis is a complex process that begins with a single cell and ends with the formation of mature embryos. Somatic embryo development involves accumulation of complex metabolites and storage reserves. This present experimentidentifiedandquantifiedendogenous phytocomponents and amino acidspresent during somatic embryogenesis of ‘Ruiru 11’.Laboratory experiments for this study were set up in the Coffee Research Institute, Kenyaat Ruiru.Third leaf pair explants were excised from 8-month-old greenhouse-grown mother plants sterilized and cultured in half strength Murashige and Skoog basal salts augmented with Thidiazuron. Once embryos had developed, the cultures were analysed for phytocomponents using GCMS andHPLC. The results showed that palmitoleic and stearic acids were highest (23.3 μg/g and 69.9 μg/g respectively) in brown embryogenic cultures. Cis 7,8 epoxy-2-methyl octadecane was highest(253μg/g) in green embryogenic cultures. (Z)-3-Tetradecene washighest(25 μg/g)in brown non-embryogenic cultures. Z,Z-3,13-Octadecedien-1-ol and (Z)-7-Hexadecenalwere highest (32.1 μg/g and 70.2 μg/g respectively) in green embryogenic cultures. Alanine content washighest (4.4μg/g) in embryos of brown cultures. Amino acids, fatty acids and their derivatives are potential biomarkers for embryogenesis.Other phytocomponentsshould be identified and their role in coffee somatic embryogenesis determined. Further studies regarding the status of the phytocomponentsidentified in the present study, especially in particular stages of embryo development are needed to propose treatments to improve coffee somatic embryo development.
Participants in a Conference of Commonwealth Education Ministers
(2022-10-01) Isutsa, D.K.
Participants in a seminar
(2022-07-01) Isutsa, D.K.
PRODUCTION OF MINERAL NUTRIENT-RICH MULTIPURPOSE PUMPKIN LEAFY VEGETABLES USING INTEGRATED NITROGEN, MULCH AND GA3
(2022-04) Isutsa, D.K.; Mwaura, M.M.; ; ;
Understanding the effect of nitrogen, mulch and gibberellic acid on minerals and metabolites in multipurpose pumpkin (Cucurbita moschata Duch) is important since it is a dependable source of food, providing families producing it with various diets that contribute to household food and nutrition security. However, production of the pumpkin using optimal or integrated inputs has not yet been embraced in most African countries, resulting in underrealization of its maximum potential. To respond to this challenge, a split-split plot experiment arranged in randomized complete block design and replicated three times was conducted for two seasons from January 2019 to July 2020. The nitrogen (0, 50, 100 and 150 kg N/ha) was assigned to main plots, mulch (no mulch, black-painted and unpainted rice straws) to sub-plots, and gibberellic acid (GA3) (0 mg/L, 40 mg/L and 80 mg/L) to split-plots. Nitrogen was applied as calcium ammonium nitrate (CAN) in two equal doses for each rate at three weeks postemergence and at the beginning of flowering. The black-painted and unpainted rice straws were placed on plots after land preparation. The GA3 solution was sprayed to plants using a 1-L sprayer, starting with 40 mg/L, followed by 80 mg/L, once during the fourth week post-emergence. Data collection was done fortnightly from the fourth week after emergence up to fruit harvest stage. Data values were subjected to analysis of variance using SAS software version 9.3 and means separated using the least significant difference test at α=0.05. All the measured parameters were significantly (P<0.05) different. Highest levels of K and Mg were obtained for 100 kg N/ha. On the other hand, P and beta-carotene were highest where unpainted rice straws were used, while application of 80 mg/L GA3 yielded high amounts of P and K. Results further showed that combined N fertilizer, mulch and GA3 consistently had significant (P<0.05) effects on N, P, K, Mg and beta-carotene (highest 23 ppm was for N1M1GA1). Therefore, sole nitrogen fertilizer, mulch, GA3, and combined rates that promote the desired mineral nutrient and beta-carotene contents in multi-purpose pumpkin leaves should be adopted and applied, depending on the kind. Keywords: Minerals, metabolites, multipurpose pumpkins, leaves, nitrogen, mulch, GA3
Relationships of Selected Endogenous Factors Associated with Direct Somatic Embryogenesis of Coffee (Coffea arabica L.)
(Journal of Advances In Agriculture, 2018-05-30) Mayoli, R.N.; Isutsa, D.K.; Nyende, A.B.; Mweu, C.M.; ; ;
Coffee is one of the most important cash crops produced in the world with great economic returns to growers and national gross domestic product. Somatic embryogenesis is a morphogenetic processes leading to plantlet regeneration and these processes are coupled with changes in the levels of primary metabolites. The present experiment established relationships of endogenous substances with direct somatic embryogenesis of coffee ‘Ruiru 11’. Laboratory experiments were set up at Coffee Research Institute, Ruiru-Kenya between 2014 and 2017. The set up was in a completely randomised design, replicated three times and repeated once. Third leaf pair explants were excised from 8-month-old greenhouse-grown mother plants and cultured in half strength Murashige and Skoog basal salts augmented with Thidiazuron. Once embryos had developed, the cultures were analysed for endogenous substances using HPLC and GCMS. Sucrose, phenolics, alkaloids, amino acids, fatty acids and their derivatives correlated positively, whereas fructose and glucose correlated negatively with the other biochemical components.Endogenous sucrose, chlorogenic acid, caffeine amino acid, fatty acids and their derivatives are potential biomarkers for coffee somatic embryogenesis, whereas endogenous fructose and glucose are inhibitors of the same. Further studies regarding the status of the biochemical components, especially in particular stages of embryo development should be conducted to establish treatments that can improve coffee direct somatic embryo development.
Synchronous Learning Demonstration
(2022-07-01) Isutsa, D.K.