Low cost alternatives to Agar in the micro propagation of Banana (Musa spp.)

Abstract

Banana (Musa spp) is a plant genus of extraordinary significance to human societies, producing the fourth most important food in the world (FAO, 2002). Banana is traditionally propagated using suckers. However, this method has short comings; for example, diseases can be carried to the new plant through the suckers used, a lot of time is required for suckers to grow into individual plants, bulky to transport and a high risk of variety mix up (Njukwe et al.,2013). Micro propagation can be used to solve these challenges however the resources for this process are not affordable. These resources and technologies include media for regeneration, lighting, infrastructure and others. Agar as a gelling agent is the most expensive requirement for micro propagation (Adelberg et al., 2006) yet it can be replaced with other gelling agents. This is because it doesn’t provide any nutritional value. Replacing agar with locally available gelling agents like starch will make micro propagation of banana more affordable hence providing access to healthy and uniform planting materials to farmers. This will boost their house hold income and contribute to food security. In this study, the potential of corn and cassava starch to replace agar was investigated. Starch from cassava varieties (NASE 14 and NARO CAS 1) and Corn starch (Zesta) were used in this study. 15%, 17.5%, 20%, 30%, 40%, 60% of each starch was boiled in 100ml of water so as to attain 2 concentrations that formed a suitable gel. 17.5g and 20g of each starch were selected and used to replace agar. The regeneration of explants was then observed over time in comparison to explants grown on media with commercial agar. The results indicated there was a significant difference in the number of days taken for the first shoot to appear between the different gelling agents as shown; χ2(6) = 22.87, p < .001, with a mean rank score of 21.5 days for 22.5g of NASE 14, 17 days for 30g of NASE 14, 6 days for 22.5g of Naro Cas 1, 14 days for 30g of Naro Cas 1, 10.5 days for 22.5g of Corn starch, 21.5 days for 30g of Corn starch, 2 days for Agar. The difference in the mean rank between the starches and Agar shows that the substitution of agar affects the regeneration of the explants. Agar is still the best gelling agent but research can be carried out to improve the alternative starches as replacements for Agar.