GEOGRAPHICAL VARIATIONS IN ELEMENTAL COMPOSITIONS OF TWO PESTICIDAL PLANTS FROM THREE AGRO-ECOSYSTEMS IN NIGERIA AND THEIR WOOD PROTECTION POTENTIALITY

Lawsonia inermis and Lagenaria breviflora are important tropical pesticidal plants with some potential for industrial wood protection uses. However, little is known about their elemental composition of wood protection importance. In this study, three agro-ecosystems: Guinea savannah (A), Dry rainforest (B), and Fresh water swamp forest (C) were selected and from each zone Lawsonia inermis leaves and Lagenaria breviflora fruits were collected and extracted. Six most important elements: arsenic (As), boron (B), chromium (Cr), copper (Cu), lead (Pb) and zinc (Zn) used to formulate outlawed standard wood preservatives, were quantitatively analysed by the spectrophotometric method. Data were analysed using analysis of variance (ANOVA) and t-test at a 0.05. All the elements were present in both plants, with chromium being most copious. Arsenic concentrations were in the range of 1.05 +/- 0.04 to 1.19 +/- 0.02 mg kg(-1) for L. inermis and 1.16 +/- 0.05 to 1.34 +/- 0.10 mg kg(-1) for L. breviflora. Boron ranged from 1.59 +/- 0.09 to 1.75 +/- 0.06 mg kg-1 for L. inermis and 2.15 +/- 0.24 to 3.00 +/- 0.14 mg kg(-1) for L. breviflora. Chromium ranged from 28.94 +/- 0.21 to 44.15 +/- 0.13 mg kg(-1) for L. inermis and 0.63 +/- 0.05 to 21.55 +/- 0.47 mg kg(-1) for L. breviflora. Copper ranged from 2.55 +/- 0.17 to 11.35 +/- 0.17 mg kg(-1) for L. inermis and 9.94 +/- 0.21 to 15.83 +/- 0.17 mg kg(-1) for L. breviflora. Lead ranged from 21.36 +/- 0.44 to 22.86 +/- 0.11 mg kg(-1) for L. inermis and 19.41 +/- 0.33 to 32.50 +/- 0.47mg kg(-1) for L. breviflora. Zinc ranged from 2.35 +/- 0.19 to 21.85 +/- 0.19 mg kg(-1) for L. inermis and 6.18 +/- 0.10 to 7.10 +/- 0.14 mg kg(-1) for L. breviflora. Lawsonia inermis and Lagenaria breviflora from Dry rainforest had significantly high pesticidally relevant elements, producing extracts that could be best explored as bio-preservatives for wood protection. Further research covering all the agro-ecosystems with individual and extract synergising tests against wood degrading agents are suggested.