Genotoxicity and Cytotoxicity Induced in Zygophyllum fabago by Low Pb Doses Depends on the Population’s Redox Plasticity

Lead (Pb) soil contamination remains a major ecological challenge. Zygophyllum fabago is a candidate for the Pb phytostabilisation of mining tailings; nevertheless, the cytogenotoxic effects of low doses of Pb on this species are still unknown. Therefore, Z. fabago seeds collected from non-mining (NM) and mining (M) areas were exposed to 0, 5 and 20 µM Pb for four weeks, after which seedling growth, Pb cytogenotoxic effects and redox status were analyzed. The data revealed that Pb did not affect seedling growth in M populations, in contrast to the NM population. Cell cycle progression delay/arrest was detected in both NM and M seedlings, mostly in the roots. DNA damage (DNAd) was induced by Pb, particularly in NM seedlings. In contrast, M populations, which showed a higher Pb content, exhibited lower levels of DNAd and protein oxidation, together with higher levels of antioxidants. Upon Pb exposure, reduced glutathione (GSH) and non-protein thiols were upregulated in shoots and were unaffected/decreased in roots from the NM population, whereas M populations maintained higher levels of flavanols and hydroxycinnamic acids in shoots and triggered GSH in roots and shoots. These differential organ-specific mechanisms seem to be a competitive strategy that allows M populations to overcome Pb toxicity, contrarily to NM, thus stressing the importance of seed provenance in phytostabilisation programs.

Growth performance of Khaya senegalensis seedlings influenced by provenances and latitudinal gradients in the nursery

Seedling growth performance is germane and pertinent in plant variables when analyzing tree provenance trials as it indicates its adaptability of the seed to the environments/habitat. The study was undertaken to examine the comparative studies on seedling performance of Khaya senegalensis at nursery stage in Forestry Research Institute of Nigeria. Seeds from four sources in different States in Nigeria: Oyo, Borno, Jigawa and Kano States were collected and planted to observe their morphological attributes. Seedlings variables (Plant height, collar diameter and number of leaves) were observed and recorded fortnightly for sixteen (16) weeks after germination was completed. It was observed that seeds from Oyo state performed best while seeds from Kano state had the least performance. Provenances variation indicate genetic and environmental differences that can be utilized for afforestation programmes and thus, this study recommends the seeds from Oyo state for large scale afforestation since it performed best. Keywords: Khaya senegalensis, seed provenance, seedling height, collar diameter and number of leaves.

Effects of seed provenance and growth media on the growth performance of Vitellaria paradoxa C.F. Gaertn.

This work investigated the effects of seed provenance and growth media on the growth performance of Vitellaria paradoxa C.F. Gaertn. Seeds were extracted from fresh fruits collected from Eruwa, Saki and New-Bussa and sown into six media in black polythene pots: top soil + sawdust (1:1); river sand + top soil (1:1); river sand + sawdust (1:1); top soil only; sawdust only and river sand. The experiment was 3 x 6 factorial laid in a Completely Randomized Design. Germination, seedling height, collar diameter, number of leaves and leaf area were evaluated. Data collected were subjected to Analysis of Variance (ANOVA) at p<0.05). Seeds from New-Bussa sown on river sand + top soil (1:1) had the highest germination percentage (92%) while the seeds from Saki sown on top soil only had the least of 74.7%. River sand + top soil medium had the longest seedling growth with 5.41 cm; also rated second in collar diameter (4.07 mm) and leaf area index (47.95 cm2). Thus, top soil based medium, especially river sand + top soil is recommended for good growth performance of this species collected from any of the three provenances.Keywords: Pseudo–radicle, germination, seed source, seedling vigour, traits.