Browsing by Author "Munyiri, S.W."

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    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.
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    Resistance to spotted stem borer in commercial maize hybrids and open pollinated varieties in Kenya. Contributions from the 3rd Africa-Wide Women and Young Professionals in Science Competitions.
    (2014) Munyiri, S.W.; Mugo, S.N.
    ABSTRACT Lepidoptera stem borers are major maize insectpests estimated to be responsible for annual losses of around 15% in sub-Saharan Africa and 13.5% in Kenya. The spotted stem borer (Chilo partellus Swinhoe, Lepidoptera: Crambidae) is the most widespread and damaging field pest. The objective of this study was to evaluate the resistance of commercial maize hybrids and open-pollinated varieties (OPVs) to C. partellus. Eighty-five hybrids, 15 OPVs, and selected stem borer-resistant hybrids were evaluated for resistance to stem borers using artificial infestation in the field for two seasons at KARI Kiboko Centre, Kenya. The α-lattice design replicated three times was used in 2 × 5 m row plots spaced at intervals of 0.75 × 0.25 m. Ten plants in each plot were artificially infested with five stem borer neonates 3 weeks after planting. The remaining plants were concurrently treated with a pesticide. Data were collected on leaf damage score, stem borer exit holes, stem tunnelling, plant height and grain yield. A selection index based on damage parameter traits was computed and used to group the genotypes into susceptible and resistant categories. Data were analysed using the SAS package and means were separated using Fisher’s protected least significance difference (LSD) at P < 0.05. The genotypes differed significantly (P < 0.05) in stem borer resistance. The CIMMYT resistant hybrid controls showed the highest resistance with a selection index of 0.61. Commercial hybrids DHO1, PH1 and PH3253, and OPVs ECA-STRIGOFFVL- 102-#-#, KDV1-1 and KDV1-2, were the most resistant with a selection index of 0.77. It was concluded that commercial hybrids and OPVs grown in Kenya display an appreciable level of resistance to maize stem borer. The new CIMMYT genotypes from the Insect Resistant Maize for Africa (IRMA) project, developed for borer resistance, remain the most superior in resistance. The resistant genotypes should be promoted for production and exploited for breeding in the relevant maize-growing ecologies.