Small-holder utility-based phyto-ionomic diversity mapping at Lake Basin sites in the interest of nutraceutical-implied security

Abstract

Continued land sub-division in the smallholder Traditional Agro-Ecologies (TAGEs) together with the changing circumstances of climatic variability, reduced land productivity, external influences, commercialization tendencies, and growing markets for specific products, have led to increased challenges regarding land use decisions. A reduction in the agro-phyto-diversity in smallholder farms which has resulted into reduced dietary diversity in TAGEs may be indirectly attributed to these changes. Dietary diversity as an aspect of agro-phyto-diversity derives its qualitative and quantitative food and nutrition importance from the interactions between the plants' genetic potentials and the environment. Among other parameters, food and nutrition quality are particularly important in terms of the micronutrient density/quality which addresses a hidden hunger. In this regard, the smallholder farms where the foods are produced may be looked at as the Small-Holder Utility-Based Ionomic Diversity Units or SHUB-Ionomic Diversity Units (SDUs). This study thus endeavoured to assess the state of SHUB-Ionomic diversity as a general aim by investigating its linkage to micro-foodshed conditions and women-operated land use practices at Lake Victoria Basin (LVB) Kenyan Eco-region Sub-basin site. The specific objectives of the study were: (1) To determine the state of agro-phyto-diversity in smallholder traditional agro-ecologies of Esibuye and Vihiga; (2) To determine the agro-phyto-diversity and soil mineral micronutrient contents in the micro-SDUs or smallholdings, linked to 'View-walk' landscape morphology of the SDU and; (3) To map out the 'view-walk' agro-phyto-diversity and nutrahealth-implied ionomic variation (NHIV). The study design was hierarchical in which 'view-walk' sections were nested within SDUs within TAGEs within Lake Victoria-Kenyan sub-basin within Lake Victoria Basin. The TAGEs were Vihiga Upper hill (the VU) ecology in Vihiga district and the Esibuye Foothill Lower (the EFL) ecology in Emuhaya district. Fifteen SDUs within each of the TAGEs were selected and sectioned into 'view-walk sections as determined by an interaction between the topography referenced 'walkshed' and the house position referenced 'viewshed'. There were five 'Viewshed' positions described as: Near-house, Left Mid-farm, Right Mid-farm, Left Far-farm and Right Far-farm) juxtaposed with 3 'Walksheds' namely: Upland, Sloped and Valley land use types. An individual SDU (farm unit) thus had 15 view-walk sections to it. Data were acquired by carrying out agro-phyto-diversity inventory and micronutrients content analysis of plant samples (n=95 of 2008 short rains accessions and n = 35 of 2009 accessions) and soil samples (n= 92) using X-Ray Fluorescence spectroscopy. Agro-Phyto-diversity-Directed (APD) questionnaires were also administered to the smallholder women operators to determine the trends in agro-phyto-diversity 'allocationing' and 'locationing' as well as related information regarding popularization and use of species. Some 157 and 151 accessions were encountered in the VU and EFL ecologies, respectively, implying that the agro-phyto-diversity distribution under the two TAGEs was similar, probably due to the constant gene flow between the two neighbouring ecologies. Variation in the number of fruit, cereal & pulses and vegetable culti-groups were significantly affected by the 'view-walk' allocationing and locationing decisions at both 5% and 1% levels of confidence. The agro-phytodiversity distribution ratios between near-house: mid-farm: far-farm were 15:55:30 and 41:42:17 in Esibuye and Vihiga, respectively. These data give a sense of less land pressure in Esibuye relative to. Vihiga as may be suggested by the more intensive use of the near house sections of SDUs in Vihiga. Results for mineral micronutrient agro-phyto-diversity contents linked to 'Viewshed' and 'Walkshed' decision factors revealed that only 18% of the 130 plant accessions were of medium to high NHIV grades with score-card grades ranging from 5 to 8 and 82% of all accessions were of low NHIV grades with score-card grades from 1 to 4. Three amaranth accessions (S09F30VNU P74, S09F38ENU P70, and S09F40ENU P84) and one local kale accession (S09F33ENU P87) were singled out for being the top graded micronutrient dense in two consecutive seasons even though they were not among the popularized species. Mapping of NHIV grades on the SDU sections suggested that plants growing near the house and possibly accessed more readily may be those that are generally of the low to medium mineral micronutrient density grades and this may be due to the fact that the near house position in smallholder agro ecologies is dominated by vegetable species that have less residues resulting into more nutrient mining. The staple food crops such as maize, bananas, and beans were the most popularized and also the most conserved and 'improved' by adoption of new varieties in the study area. The disappearing crops were identified as comprised of cassava, finger millet, carrots, bulrush millet, sorghum and sweet potatoes. The market was found to be the leading source for new planting materials and thus very important in movement of germplasm between ecologies. Conclusions made are that agro-phyto-diversity in Vihiga and Esibuye SDUs is fairly limited and is facing a further risk of constriction; in effect, hidden hunger could, therefore, be a risk in TAGEs. Popularization of the more micronutrient dense ionomes, while sustaining agro-phytodiversity and avoiding un-popularization of indigenous species, is recommended as a sustainable strategy of advancing the utility based management of bio-resources in TAGEs.