Gordian C. Obute

Targeted mutagenesis in Vigna unguiculata (L.) Walp. and Cucumeropsis mannii (NAUD) in Nigeria

The mutagenic effects of 0.2% aqueous solution of colchicine on gross and micromophological features of seedlings of Vigna unguiculata (L) Walp. and Cucumeropsis mannii (Naud.) were investigated. Terminal buds of two-week old seedlings were assaulted with 0.2% colchicine by the cotton plug and micro syringe methods and performances were monitored until maturity. Colchicine-treated V. unguicu-lata seedlings were observed to grow slower, had malformed leaves, flowered late and produced less number of seeds per pod than the control. Mean values of features like stomatal indices on both the abaxial and adaxial surfaces, terminal leaflet dimensions and trichome distribution between the treated and control were found to be significantly different. In contrast, treated seedlings of C. mannii flowered and fruited earlier than the case of control material. However, growth was also slowed down by the treatment while features like stomatal indices and trichome distribution were not significantly different. The results here have shown that apart from doubling of chromosomes, colchicine can also be used to induce other mutagenic changes which may be of agronomic utility.

Impact of four-dimensional seismic and production activities on the mangrove systems of the Niger Delta, Nigeria

Reconnaissance survey and laboratory appraisal of the mangrove system in seven communities in the Niger Delta (Nigeria) endangered by seismic and production operations revealed several alterations of soil, sediment, and vegetation. Hydrocarbon content in the range of 0.3–1.1 mg/100 g was extracted within the proximities of spill sources and seismic lines. The prospect area covered by our investigation was characterized by a mixed mangrove forest dominated by Rhizophora racemosa. It was observed that the construction of the seismic lines was responsible for the vegetal disorientation recurrent in the area. The grass, Paspalum vaginatum, and the saltwater fern, Acrostichum aureum, were found at the fringe of most dredge spoils. The characteristic tidal inundation which increases mobility of the substrate, salinity fluctuation, and anoxia may also have contributed, at least in part, to the observed despoliation of some of these species found within the vicinities of the seismic lines and hydrocarbon percolation. Extensive revegetation program is recommended to ensure an effective restoration process of this ecologically fragile zone.