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Articles by D.M. Musyimi
Total Records ( 6 ) for D.M. Musyimi
  D.M. Musyimi , G.W. Netondo and G. Ouma
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  D.M. Musyimi , J.A. Ogur and P.M. Muema
  Phytochemical and anti-microbial properties of the methanol extracts of Aspilia mossambicensis (family, Compositae) were studied. The plant has been used by traditional healers to treat skin diseases, wounds, gonorrhea, abdominal pains, respiratory problems and malaria. Bacteria used for antimicrobial analysis consisted of clinical strains of Streptococcus pyogenes (gram positive) and Salmonella typhi (gram negative) bacteria and one strain of fungi (Aspergillus niger). Phytochemical screening of the plant leaves and roots of A. mossambicensis revealed that the plant contains active compounds of flavonoids, alkaloids, saponin, steroids, carbohydrates and anthraquinones. The methanol extract showed antimicrobial activity against the three microorganisms at relatively lower concentrations. Leaves extracts showed higher level of growth inhibition of S. pyogenes, followed by S. typhi and A. niger, respectively. Root extracts showed higher growth inhibition for A. niger, followed by S. typhi and S. pyogenes in that order. In comparison leaves extracts showed better microbe growth inhibition than root extracts and was attributed to absence of aldehydes in the roots, or a more concerted synergistic activity of active compounds present in the leaves. The study has shown that species of Aspilia mossambicensis have considerable activity against gram positive bacterium Streptococcus pyogenes, gram negative bacterium Salmonella typhi and one fungal strain, Aspergillus niger. The study supports the previous claims by traditional healers of the plant to heal several diseases in traditional communities in Kenya. The study provides a strong evidence for new sources of antimicrobial drugs from this plant.
  D.M. Musyimi , J.A. Ogur and P.M. Muema
  Phytochemical compounds and anti-microbial properties of the methanol extracts of Aspilia mossambicensis (Compositae) were studied between March and April, 2007 at Maseno University, Kenya. The bacterial used for the antimicrobial analysis consisted of clinical strains of Streptococcus pyogenes (gram positive) and Salmonella typhi (Gram negative) bacteria and one strain of fungi (Aspergillus niger). The methanol extract was active against the three microorganisms. Leaves extracts showed greater microbial growth inhibition  in  comparison  to  root  extracts.  The  phytochemical  screening  for  the plant leaves and roots of A. mossambicensis revealed the presence of active compounds of flavonoids, alkaloids, saponin, steroids and anthraquinones. The results from the present study have shown that species of Aspilia mossambicensis have considerable activity against the gram negative bacterium Salmonella typhi, gram positive bacterium Streptococcus pyogenes and one fungal strain Aspergillus niger. Streptococcus pyogenes experienced lesser growth inhibition with root extracts compared to the other two microbes. It is possible that the growth inhibition observed in the study occurred due to presence of different chemical compounds. Absence of aldehydes in roots but not in leaves could explain the greater growth inhibition of S. typhi and A. niger. Pit method was a better method for testing antimicrobial activity than disc method in this study.
  D.M. Musyimi , G.W. Netondo and G. Ouma
  This study was conducted to investigate growth and gas exchange characteristics of avocado seedlings growing under different salinity levels under naturally illuminated greenhouse conditions, in order to relate this physiological information to the ecology of this avocado cultivar. Plants grown in 4.5 L plastic pots containing soil were subjected to 0 (control), 15, 30, 45 and 60 mM NaCl salinity treatments. The measured parameters started to show significant differences (p≤0.05) by day 7. Interactions between salt treatments and duration of salt exposure were highly significant at p≤0.05. Net photosynthetic rate (PN), stomatal conductance (gs), transpiration rate (E) and chlorophyll (chl) concentration decreased in response to increasing salt concentration in the growth medium. Water use efficiency (WUE) decreased in all the treatments during the time course of experiment. Substomatal CO2 concentration (Ci) and chloride ions content increased with increasing salt concentration of the growth medium. It is suggested that the greater inhibition of CO2 fixation may be due to impairment of photosynthetic apparatus. Treatment consisting of 60 mM NaCl caused maximum growth reductions. The findings in this study demonstrate that NaCl salinity hampers growth and gas exchange processes of avocado plants and improvement in salt resistance of avocado rootstock under study is more likely to come from increasing further screening of more avocado rootstocks for salt tolerance or resistance.
  D.M. Musyimi , G.W. Netondo and G. Ouma
  A study was conducted to evaluate the effect of different salinity levels on the growth, gas exchange, soil respiration and nutrient uptake of 8-month-old-avocado seedlings (var. Puebla) grown under naturally illuminated greenhouse conditions. Plants grown in 4.5 L plastic pots containing soil were subjected to 0 (control), 15, 30, 45 and 60 mM NaCl salinity treatments for eight weeks. The analysis of growth parameters such as stem diameter, leaf number, shoot height, root and shoot dry matter content showed that they were significantly affected by salinity of the growth media at (p<=0.05) at the end of the experiment. Net photosynthetic rate (PN), stomatal conductance (gs), transpiration rate (E), leaf water content and chlorophyll (chl) concentration decreased in response to increasing salt concentration in the growth medium. Intercellular CO2 concentration (Ci) and chloride ions content increased with increasing salt concentration of the growth medium. On the other hand, the uptake of other elements was inhibited by the increasing water salinity. Soil respiration of the rooting medium decreased with increasing salt concentration and this caused a decrease in shoot and root total biomass The high intercellular CO2 concentration observed at the higher salinity levels of 45 and 60 mM NaCl in comparison to control plants may indicate a greater inhibition of CO2 fixation or impairment of the photosynthetic apparatus by the sodium chloride toxicity, while the reduced soil respiration may imply low microbial activity and reduced root respiration in the soil rhizosphere caused by salt toxicity. The results obtained demonstrated that low salinity levels such as 45 and 60 mM NaCl highly inhibited avocado seedling growth, nutrients uptake and gas exchange capacity, under the set experimental conditions and that decline in stomatal conductance is accompanied by inhibition of PN due to salt stress. The results also suggest that soils which are saline or irrigating avocado plants with saline water may inhibit nutrient uptake, photosynthesis and hence retarded growth of the avocado seedlings.
  D.M. Musyimi
  Under natural conditions, photosynthesis and stomatal conductance are normally limited by Photosynthetically Active Radiation (PAR), temperature, water stress and salinity. A study was conducted at Maseno University, Kenya in February, 2005 to investigate on growth and physiology of avocado seedlings tolerance to salinity under naturally illuminated glasshouse conditions. Plants were grown in 4.5 L plastic pots containing soil and were subjected to either 0 (control) or 60 mM NaCl salinity treatments. Growth parameters, net photosynthesis, stomatal conductance, transpiration rate, Water Use Efficiency (WUE) and leaf chlorophyll content were all reduced by the salinity of the growth medium. Intercellular CO2 concentration and leaf chloride content were increased by the salt treatment. The study demonstrated that PAR and salinity play a substantial role in limiting net photosynthesis in this variety of avocado (Puebla). The greater intercellular CO2 concentration at medium salt levels may indicate impairment of photosynthetic apparatus. Based on observations of water use efficiency it can be concluded that the stressed plants somehow had an elaborate mechanism of water conservation. More research is needed for different avocado rootstocks and soil types over a wide range of environmental conditions.
 
 
 
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