Culture "in vitro" et multiplication rapide de plantes à tubercules et racines au Cameroun

Auteurs

    Simon Zok
    Anne E Sama
    Léopold Nyochembeng
    James Tabi Tambong
    Xavier Ndzana
    Joseph-Gabriel Wutoh

Résumé

In Cameroon, yam (Dioscorea spp.), cocoyam (Xanthosoma sagittifolium) and cassava (Manihot esculenta) are the most important staple foods. The scarcity and high cost of good quality planting materials and field susceptibility to viral and fungal diseases are major constraints for increased production of these crops. At the Jay P. Johnson Biotechnology Laboratory at Ekona (Cameroon), 8 years of research led to successful mass production of plantlets and field testing of the three crops after acclimatization. Microbial contaminations in yam cultures were drastically reduced from 80% to 4% through double-surface sterilization, using calcium hypochlorite at 8% and 6%, respectively. The establishment medium, made of MS minor and major elements, supplemented with kinetin (2 mg/l) and indolylacetic acid, IAA (2 mg/l), was successfully used to regenerate yam plantlets (Table 1). Multiple shoot formation was induced in all media containing kinetin; a high number of shoots was obtained with concentrations ranging from 5 to 10 mg/l, associated or not with IAA (Table 2). Acclimatization of tissue culture derived plantlets was achieved in various substrates. For yams, about one hundred thousand planting sets can theoretically be produced per year from one tuber. With cocoyam (Table 3), B5 basal medium devoid of growth hormones was the most suitable medium for plantlet regeneration, with success rates ranging from 80 to 90%. With regards to axillary bud proliferation, media containing BAP (0.1 to 1 mg/l) or kinetin (1 to 1.5 mg/l) were the most effective. More than 50 secondary shoots were formed in 2 months from each initial bud, indicating that a combination of this procedure with efficient bud subculturing could theoretically produce about 6,000,000 shoots per year. Through tissue culture, secondary dormant buds on cocoyam rhizomes were used directly as a source of explants, thus enhancing mass multiplication since each rhizome produced 800 to 1,000 buds depending on the age. By aseptic subculturing of multiple buds, a single rhizome can produce thousands of plantlets in 1 year. Acclimatization of developed plantlets was successfully done using inexpensive, locally-available substrates. A combination of topsoil and coffee parchment gave the best plant survival rate, and field transplantation was not problematic. Tissue culture-derived cocoyam plants performed better (in terms of growth and earliness in tuberization), compared to normally propagated plants. Trials with improved cassava clones 8017, 8034 and 8061 (Table 3), were aimed at achieving shoot formation, elongation, and rapid clonal propagation of plantlets from subcultured nodes. Subculturing cassava plantlets developed in MS mineral medium supplemented with 0.05 mg/l naphtalene acetic acid (NAA) and 0.5 mg/l BAP provided a reliable means for rapid multiplication of cassava. This method is routinely used for mass culture of available clones, giving a high multiplication rate of 80, as compared to 10-15 using traditional cassava propagation methods. Field-adapted tissue culture derived cassava showed robust growth, similar to their normal counterparts, and over 400,000 cuttings from tissue culture-derived plants have been distributed yearly to farmers over the past 3 years.

Affiliations

Jay P. Johnson Biotechnology Laboratory, Institut de la Recherche Agronomique, PMB 25 Bues, Cameroun.

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Publié

1998-01-01

Comment citer

Zok, S., Sama, A. E. ., Nyochembeng, L., Tambong, J. T. ., Ndzana, X., & Wutoh, J.-G. (1998). Culture "in vitro" et multiplication rapide de plantes à tubercules et racines au Cameroun. Cahiers Agricultures, 7(1), 63–66 (1). Consulté à l’adresse https://revues.cirad.fr/index.php/cahiers-agricultures/article/view/30068

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