Effects of growth media on growth and commercialisable percentage of disease-free cassava cultivar KM140 (Manihot esculenta Crantz “KM140”)

Cassava mosaic disease (CMD) is one of the most serious diseases that has caused heavy losses in starch yield. In vitro propagation from CMD disease-free cassava is the optimal method to produce healthy seedlings. Identification of a suitable growth medium for the development of ex vitro plantlets during the acclimation stage is an important step in order to obtain healthy plant. In this study, common substrates such as coir, rice husk ash, and vermicompost were mixed in different proportions to create formulations for the autotrophic stage of disease-free KM140 cassava plants. The parameters measured including plant height, number of leaves, stem diameter, number of branches, root length, dry matter ratio of leaves, roots, survival rate, and percentage of nurse stage cassava plantlets were evaluated. The results showed that cassava plants were transferred from in vitro to ex vitro environments gained a survival rate of 84.5% in coir substrate after 1 week. The growth medium contained a mix of 85% coir + 10% rice husk ash + 5% vermicompost was suitable for the growth and development of KM140 cassava plantlets. In this condition, the plantlets reached height of 38.8 cm with 22.0 leaves and the percentage of commercialisable plantlets reached 85.3%.