Department of Biological Sciences

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    Development of in vitro propagation protocol for some recalcitrant cassava (Manihot esculenta Crantz) genotypes in Sierra Leone
    (Academic Journals, 2018-05-02) Sesay, Janatu Veronica
    A study on rapid propagation of cassava through tissue culture was conducted with three elite cassava genotypes: Slicass 6, Slicass 11 and Cocoa from Sierra-Leone. They showed slow growth in Murashige & Skoog (MS) basal medium which was proven to be optimal for a vast number of cassava accessions. Prior to mutation induction, a large population needs to be produced for mutagen susceptibility test and for mutant population development. The ultimate objective of this study was to investigate the effects of plant growth regulators on the shoot development of three cassava genotypes. In vivo shoot tips were sterilized and sub-cultured on MS media supplemented with six combinations of plant growth regulators (PGRs) at different concentrations. The results showed that from all media used, the MS medium with 1.0 mg/L α-naphthalene acetic acid (NAA) showed the best response for rooting (5.50), fresh weight (0.29 g), root number (10.00) and plantlet height (3.81 cm), while 0.1 mg/L 6-benzylaminopurine (BAP) was found to be more favourable to shoot development of leaves (6.38). The highest plant height and fresh weight were 3.81 cm and 0.29 g, respectively for Cocoa at 1.0 mg/L α-naphthalene acetic acid (NAA), 10.00 roots for Slicass 6 at 1.0 mg/L, 6.37 leaf numbers for Slicass 11 at 0.1 mg/L 6-benzylaminopurine (BAP) and 5.6 at 1.0 and 1.5 mg/L α-naphthalene acetic acid (NAA). These observations indicate that a supplement of 0.1 mg/L 6-benzylaminopurine (BAP) in MS medium can be useful in propagation of recalcitrant cassava and low concentration of α-naphthalene acetic acid (NAA) will be beneficial in root induction prior to acclimatization with promotion in recovery of the ex vitro plants before field assessment. Key words: Cassava, Manihot esculenta, propagation, shoot tip, 6-benzylaminopurine (BAP), α-naphthalene acetic acid (NAA).
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    Predicting the adoption of improved cassava varieties in Sierra Leone
    (Academic Journals, 2021-02-15) Sesay, Janatu Veronica
    In Sierra Leone cassava plays a major role in households’ food and income security. Plant breeders have concentrated on improved varieties with an increasing yields per unit area. This study was designed to identify factors that influence adoption or rejection of improved cassava cultivars by growers. Data were collected using questionnaires, focus group discussions and field walks; locations were selected using multistage stratified random sampling. Logistic regression was used to model uptake of improved varieties. Most farmers usually grow several cultivars and just over half have included an improved variety. Of the six improved varieties released in 2005 by the Sierra Leone Agricultural Research Institute, only SLICASS 4, was widely adopted and three were not recorded in the study. Preferred characteristics are; high yield, sweet taste, early maturity and good cooking quality. Cultivars are more likely to be adopted where; cassava is a major crop, households are experienced in cultivating cassava, they have access to research, contact with extension agents and access to cassava markets. Improved cultivars are less likely to be adopted by small households with few resources. Cassava breeders should recognize what farmers find desirable but success will depend on; communicating research, having active extension agents and good access to markets. Key words: Adoption, improved varieties, cassava, Sierra Leone.