Agronomic performance of locally adapted sweet potato (Ipomoea batatas (L) Lam.) cultivars derived from tissue culture regenerated plants

Tissue culture techniques have opened a new frontier in agricultural science by addressing food security and agricultural production issues. A study was conducted to compare growth and yield characteristics between the tissue culture regenerated and conventionally propagated sweet potato cultivars. Five locally adapted sweet potato cultivars Mugande, SPK004, Kemb10, Japon tresmesino and Zapallo were regenerated in vitro by the methods of indirect and direct embryogenesis and grown under field conditions in a RCBD replicated three times. Significant (

Chemical composition and antimicrobial activity of the essential oil of Ocimum gratissimum L. growing in Eastern Kenya

Hydro-distilled volatile oils from the leaves of Ocimum gratissimum L. (Lamiaceae) from Meru district in Eastern Kenya were analysed by gas chromatography-mass spectrometry (GC-MS) and also evaluatedfor antimicrobial activity. The oil was dominated by monoterpens which accounted for 92.48%. This monoterpene fraction was characterized by a high percentage of eugenol (68.8%). The other major monoterpenes were methyl eugenol (13.21%), cis-ocimene (7.47%), trans-ocimene (0.94%), -pinene (1.10%) and camphor (0.95%). The sesquiterpenes present in fairly good amounts were germacrene D(4.25%) and trans-caryophyllene (1.69%). The minor  sesquiterpenes were -farnesene (0.85%) and -bisabolene (0.74%). The antimicrobial activities of the essential oils were evaluated against both Gram positive (Staphylococcus aureus, Bacillus spp.) and Gram negative (Escherichia coli, Pseudomonasaeruginosae, Salmonella typhi, Klebisiella pneumoniae, Proteus mirabilis) bacteria and a pathogenic fungus Candida albicans. The oil had pronounced antibacterial and antifungal activities on all themicrobes

Selection of Drought Tolerant Bread Wheat Genotypes using Root Characteristics at Seedling Stage

The following study was carried out to determine the suitability of the box technique for screening wheat for drought tolerance and the general characteristics of wheat seedlings related to resistance to drought. Three commercial wheat varieties, Duma, Kenya Mbweha and Mbuni which are tolerant, moderately tolerant, and susceptible respectively, were screened together with 3 lines R830, R831 and R748 which have been identified to show drought tolerance characters. The 6 were planted in boxes measuring 0.03m x 1m x 0.3m after this being determined as the best size for screening wheat seedlings. The rooting pattern of these genotypes was studied. Generally, drought resistant genotypes had more roots in the crown region with nodal and seminal roots concentrated between the soil surface and 70 cm deep. Susceptible genotypes had fewer roots in the crown region. Drought tolerant varieties were not necessarily deep rooted. Drought resistant genotypes had high absorptive surface area of up to 9.6 mm3 while susceptible ones had as low as 3.5 mm3. Root depth, total root length, relative absorptive surface area, number of roots, root spread, length of the longest root and root concentration were significantly different (

Changes to water management and declining pastoral resilience in Marsabit County, northern Kenya: The example of Gabra wells

Abstract: In this article, we provide a review of research on the existing and abandoned wells in Marsabit County, Northern Kenya, and associated Indigenous Knowledge concerning water governance, institutions of leadership, and how these have contributed to sustaining a resilient pastoral economy in these harsh landscapes. The article discusses the socio‐ecological systems that have been maintained by pastoralists for generations, linking their sustainability to leadership structures and institutional memory, with a particular focus on the Gabra. It further highlights internal and external interventions by governmental and nongovernmental organizations that are expected to improve the livelihoods of the Gabra and other pastoralists inhabiting the area, but have sometimes had a negative effect on the traditional strategies of water governance and socio‐ecological systems, undermining the long‐term viability of the pastoral economy in Marsabit. This article is categorized under: Human Water > Water Governance Human Water > Value of Water Human Water > Rights to Wate

Drought tolerant wheat varieties developed through mutation breeding technique

In search for higher yielding drought tolerant wheat varieties, one of the Kenyan high yielding variety 'Pasa' was irradiated with gamma rays (at 150, 200, and 250gy) in 1997 so as to induce variability and select for drought tolerance. Six mutants ((KM10, KM14, KM15, KM18, KM20 and KM21) were selected at M4 for their drought tolerance screening. The six mutants and 2 checks, Duma and Pasa were tested for their performance in a National performance trial. The study was carried out as a National Dryland Wheat Performance Trial in 4 sites in Kenya and selection done for two seasons, 1999 and 2000. The sites were Katumani, Naivasha, Lanet and Mogotio, which represent marginal rainfall areas in Kenya. Randomised complete block design was used and replicated three times. Data on plant height, yield and hectolitre weight were taken. The results showed that mutant line KM21 and KM14 performed significantly (

Leaf storage conditions and genomic DNA isolation efficiency in Ocimum gratissimum L. from Kenya

Storage of plant tissues for DNA is important to avoid degradation of DNA. Preliminary studies were conducted on Ocimum gratissimum L. in order to establish the storage conditions for the collected samples before DNA extraction. Secondly, the aim was to determine the best protocol for the extraction of high quality DNA, which would later be used for molecular analysis. DNA was extracted from thesamples one month after field sampling. During the DNA extraction, four protocols were used; the modified hexadecyltrimethyl ammonium bromide (CTAB) mini preparation method described by Doyleand Doyle (1990), with reductants either mercaptoethanol or dithiothreitol; the modified sodium dodecyl sulphate (SDS) mini preparation method of Edwards et al. (1991) with redundant either mercaptoethanol or dithiothreitol. The DNA was purified, treated with RNase, quantified and examined for intactness using gel electrophoresis method. Good quality and high yield DNA  could only be extracted with the buffer containing the detergent SDS and the reducing agent dithiothreiotol

Root and shoot characteristics as selection criteria for drought tolerance in bread wheat (Triticum aestivum L.) at seedling stage under tropical environment

No Abstract. Discovery and Innovation Vol. 17(1&2) 2005: 74-8