Germination of Mansonia altissima (A. Chev.) A. Chev. var. altissima: an endangered valuable timber species in Africa

The in vitro seed germination which results in the production of disease-free seedlings and greenhouse germination of the seeds of Mansonia altissima was investigated in order to establish a better way of germination of the timber species. Five levels of GA3 treatment were used in in vitro germination with three replicate and two seeds were inoculated in each of the jam bottle. Whereas, in greenhouse germination, five levels of different treatments were used, replicated three times and each Petri plate contained 15 seeds. The experiment was repeated twice and the data from each experiment was put together and used for the statistical analysis. The results showed that seeds germination occurred eight days after inoculation in in vitro but in the case of greenhouse germination, it took only five days. For in vitro rapid germination of Mansonia altissima, the MS medium should be supplemented with 1.0 μm of GA3. Equally, in greenhouse germination, the seeds need to be soaked in 1.0 mM of GA3 for 24 hours. Alternatively, in the absence of GA3, the seeds can be soaked in water for 24 hours before broadcasting the seeds on the seedbed for germination, as this will help to identify nonviable seeds.

Study on individual and interactive effects of supplemental UV-B radiation and heavy metals on Spinacea oleracea.

The effects of supplemental ultraviolet-B (sUV-B) irradiation and heavy metals (Cd and Ni) treatment alone and in combination were evaluated on the growth, biomass and yield of spinach plants. All the stresses caused reduction in biomass yield vis-a-vis alteration in its distribution pattern with more retention in below ground parts leading to higher root shoot ratio. Absolute growth rate (AGR) decreased in all treated plants due to reduction in their height at successive growth stages. Decrease in leaf area and number of leaves due to various stresses was responsible for decline in net assimilation rate (NAR), an index of photosynthetic assimilatory capacity of the plant. Supplemental UV-B increased the bioaccumulation of Cd and Ni in the root and shoot of exposed plants as compared to the control ones. The present study suggested that soil contaminated with Cd or Ni had a more negative impact on yield with higher retention of heavy metals in spinach growing under natural field conditions and exposed with elevated UV-B.