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Articles by J.I. Kinyamario
Total Records ( 3 ) for J.I. Kinyamario
  J.I. Kanya , T.P. Hauser , J.I. Kinyamario and N.O. Amugune
  Hybridization potential between cultivated rice (Oryza sativa) and wild rice (Oryza longistaminata) was studied in Kenya. At first seeds of the two parents were sown and their growth patterns established. At maturity, F1 hybrid seeds were generated from manual crosses between the two Oryza species under screen house conditions. The F1 hybrid seeds and seeds of the two parents were sown to compare the hybrids’ growth patterns and seed production with those of the parents. Correlations of seed production with other and morphological discrimination of hybrids from the parents were also scored. This study showed that hybridization between the two species can occur resulting in 6% hybrids seeds. On growth patterns, O. longistaminata plants grew taller than F1 plants which grew taller than O. sativa plants. The three types of plants continued to grow in height up to maturity but the gain in height in the hybrid and cultivar plants slowed down upon reaching the flowering stage, after the 10th week. It was also found that seed production in hybrids positively correlated with flag leaf length; while in O. longistaminata, seed produced positively correlated with plant height and panicle length. However, in O. sativa, number of seeds correlated with panicle exertion. The study also indicates that there were morphological differences (plant height, flag leaf length, panicle exertion and awn length) between the hybrids and the parents suggesting that these traits could be used as markers for identification of the hybrid plants from the parents.
  S. Sikolia , E. Beck , J.I. Kinyamario , J.C. Onyango and G. Ouma
  δ13C values of the Centrospermeae species are presented. 69.5, 28.45, 1.25 and 0.8% of the total species are C3, C4, C3-C4 and CAM photosynthetic species. The δ13C values are species dependent. δ13C values for the C3 range from -21.16 to -30.28‰ while the C4 species vary from -10.60 to -16.55‰. An exceptional δ13C value of -32.28 is reported for Chenopodium capitatum. δ13C value for the CAM species vary from -16.00 to -18.50‰. C3-C4 species includes Mollugo nudicaulis, Portulacaria afra and Portulaca sp. nov. with δ13C values -25.89, -20.93 and -15.66‰, respectively. Temperature and precipitation are the dominant causal climatic factors that influence the distribution of the C3 and C4 species inversely and by extension the δ13C values along the altitude. Other climatic factors act synergistically. A difference in the δ13C values is a biochemical dual function of the Rubisco and suberized lamella anatomical structural organization. The occurrence of some C4 species in the unusual high altitude includes Melandrium nordiflorum and Silene abyssinica and may be due to the Pyruvate Phosphate Dikinase (PPDK) enzyme functional activity. Ecological significances of the δ13C values are discussed.
  S. Sikolia , J.C. Onyango , E. Beck and J.I. Kinyamario
  Two hundred and seventy eight species of the Centrospermeae were collected at different sites in Western Kenya representing gradients of altitude and aridity. Climate data were obtained from meteorological research stations. Species were examined for C3 or C4 photosynthesis using the anatomical Kranz syndrome, δ13C values and carbon dioxide compensation points. C4 photosynthesis is a feature of modern members of dicotyledoneae is of multiple evolutionary origins. It evolved independently in members of the same family and was found in one to several genera and then often only with two to three species. C4 species are concentrated in lowland habitats subjected to high temperature, low precipitation and high evaporation. High δ13C values is associated with low water availability which is a physiological syndrome and also a feature of saline habitats. The C3 representatives of the Centrospermeae dominate in more moist and colder habitats, especially at higher altitudes. Only a few C4 species occur at high altitudes (3000-4000 m) namely Sagina gallica, Silene abyssinica and Melandrium nordiflorum. The transition zone between C3 and C4-dicot is rather narrow between 1500 to 1700 m and thus much lower than that recorded for the monocots (2000-2200 m). The general pattern of δ13C values distribution along the altitudinal gradient show that the values of -10.60 to -16.55, -17.75 to -18.87 and -18.89 to -32.42‰ that corresponds to altitudinal ranges, 0-1500, 1550-1700 and 1800-4200 m, respectively. The low altitudes are associated with drought and high temperatures. C4 and C3 dicot species can be intercropped to increase bioproductivity for the betterment of the flora and fauna in the semi-arid and arid ecosystem. C4-species are potential candidates for exploitation in the agroforestry systems especially for long-term management programmes. The present study may also be relevant for better understanding of global change with respect to the diversity of photosynthetic pathways, herbivory and vegetation dynamics.
 
 
 
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