Cassava Starch As An Alternative Low Cost Gelling Agent For Slow Growth In Vitro Conservation Of Potato

Abstract

Lack of cost-effective protocols has hampered wide-scale application of slow growth in vitro conservation of potato. Therefore, the potential of cassava starch as an alternative low cost gelling agent for potato in vitro conservation media at normal propagation temperature was investigated using a two factor experiment in a randomized complete block design for a period of 18 months. Three gelling agents: i) cassava starch (8%) + agar (0.25%), ii) cassava starch (8%) and iii) agar (0.8%) were evaluated using three varieties (Arka, Dutch Robijn and Tigoni). Plantlet survival and condition of plantlets after 18 months of conservation was comparable when cassava (8%) + agar (0.25%) and agar (0.8%) were used as gelling agents for all the three varieties and were higher than survival and condition of plantlets grown on media gelled with cassava starch (8%) alone. Plantlets grown on media gelled with cassava starch (8%) + agar (0.25%) and agar (0.8%) alone, respectively, had higher numbers of usable single node cuttings per culture than plantlets grown on cassava starch (8%) regardless of the variety. Gelling costs were reduced by 16.6 and 24.4 % when cassava (8%) + agar (0.25%) and cassava (8%) alone were used, respectively, as the gelling agents compared to agar (8%) alone. However, media gelled with cassava starch (8%) alone had poor clarity and gel strength indicating its unsuitability for conservation. All plantlets that survived the 18-month conservation period had 100% viability irrespective of the type of conservation media used that was used. Therefore, cassava starch (8%) + agar (0.25%) may be used as a cheaper alternative for agar in potato conservation media.