Theses and Dissertations

Permanent URI for this collection

https://ir.oauife.edu.ng/handle/123456789/994

Browse

Browsing Theses and Dissertations by Author "Lawanson, A. O."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Open Access
    Effects of Water Stress on Growth and Aspects of Primary Metabolism of Seedlings of Zea Mays Linn. Variety Farz 27.
    (Obafemi Awolowo University, 1985) Ebukanson, Gabriel John; Lawanson, A. O.
    Maize seedlings raised for six days were subjected to water stress treatments at 76.6% relative water content (RWC) and 66.5% RWC with appropriate controls. Growth of the maize seedlings, as measured by fresh weights, dry weights, seedling heights, leaf area index, leaf area ratio, leaf weight ratio, net assimilation rate and relative growth rate, was generally retarded by water stress. Water stress, on the other hand, effected enhanced accumulation of chlorophyll a, chlorophyll b, protochlorophyllide, protochlorophyll and phytol in the maize seedlings. The accumulation of carotenes and xanthophylls was enhanced while that of flavonoid was retarded. The levels of mitochondrial quinones, ATPase activities of the chloroplasts and mitochondria' oxidative phosphorylation activity and the activities of succinate, malate and glutamate-dehydrogenases were also generally retarded by water stress. It is suggested that, in water-stressed maize seedlings, the increased accumulation of carotenoids contributed to the increased accumulation of chlorophylls and their precursors. The retarded accumulation of mitochondrial quinones, and the retarded activities of oxidative phosphorylation and those of such enzymes as ATPases, succinate--, malate- and glutamate-dehydrogenases may be responsible for the retarded growth observed in the stressed maize seedlings. Flavonoid accumulation appears to be a better indicator of the effects of water stress on the performance of maize.
  • Thumbnail Image
    Item
    Open Access
    Metabolic Activities in Seedlings of Maize (Zea Mays Linn. CV. Farz 34) in Relation to Boron Nutritional.
    (obafemi Awolowo University, 1985) Besong, Bernard Eshua; Lawanson, A. O.
    The responses of maize seedlings to boron nutritional stress were investigated. One group of seedlings was deprived of boron while two other groups were subjected to supraoptimal concentrations of boron conditions by feeding them with five and ten times the optimal concentrations of boron. The effects of supraoptimal concentrations and/or deficiency of boron on the growth rates (as measured by their fresh and dry weights) as well as on the formation of chlorophylls, the specific activity of the ATPases, oxidative phosphorylation, succinate-, malate- and glutamate dehydrogenases, and on the level of mitochondrial quinones were studied. One supraoptimal boron level (X1OB) increased the fresh and dry weights of the seedlings while the other supraoptimal level (X5B) and the deficiency conditions decreased these parameters. Both the supraoptimal boron levels and boron deficiency conditions decreased the amounts of chlorophyll pigments. The specific activity of the respiratory enzymes as well as the level of mitochondria quinones were enhanced under the deficiency and one supraoptimal level (X5B) conditions; the increase being greater in the former group of seedlings. The other supraoptimal level (X10B), however, decreased the activity of the respiratory enzymes.