X-ray fluorescence detected variation in nutraceutic-implied mineral density in underutilized plants mapped as women-operated smallholder units in the Lake Victoria basin.

摘要

Indigenous plant biodiversity plays a key role in providing nutritional and medicinal (nutraceutical) need for smallholder farming communities. The objective of this paper was to relate farming decisions, farm landscape morphology, crop species placement points, and the nutraceutical-implied micronutrient mineral (NIMM) density. The Kisumu (Kenya), Iganga (Uganda) and Bukoba (Tanzania) lake basins were the three eco-regional environs studied and were treated as the primary hierarchical level. Two visited sites (secondary level) for reconnaissance/collection were nested within the primary level. Fifteen dominantly female households were further nested within sites (tertiary level). By means of X-ray fluorescence (XRF) spectroscopy, indigenous variant plants (accessions) encountered were collected for density. XRF analyses were backed by key informant interviews. Empirically, indigenous/traditional plant species and, by extension, their diversity in NIMM density, was a three-factor dependent variable in terms of: (a) the ethnobotanic-based farming decisions by which the NIMM indigenous/underutilized plant bio-resources encountered were purposively grown; (b) choices that were dictated by the topographic soil surface characteristics (terrain upland, steep and valley land properties); (c) near residence-referenced sequent activity occupancy (NR-SACO) episodes; and (d) natural cum farmer-guided plant selections. Women were found to be dominant players in smallholder operations and were NR-SACO-mapped with respect to their rigorous tillage operations close to the residential zone. Across the nearest residence tillage farm, the transitional tillage and the outlier tillage spectrum, the lowest percentage of tillage rigour occurred on slope, probably due to local soil aridity and reduced soil fertility. Valley-like plain sites, regardless of distance from residence, were most preferred for tillage. The 10-9-8 right-tailed nutraceutic-implied diversity cluster was the most conservative as only Corchorus olitorius (from Uganda) of all the Ugandan and Kenyan accessions fitted there with a score of 8. The 7-6-5 centre diversity cluster was less clustered. Patterns of tillage placement may be suggesting a likely influence of the topographic soil-surface effects on NIMM density via farming decisions. The above interrelationships are an efficient basis for tagging nutraceutic-implied variants on the farm by allocation to the physical tillage units for conservation and use.