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Several species of double-stranded RNA (dsRNA) were found to occur in the cassava clone Secundina, which was thought to be virus- free. A large dsRNA molecule (6.6 x 106 Mr = relative molecular mass)(L-dsRNA) was shown to be graft, but not mechanically transmitted and occurred primarily in a nucl...


Gabriel, C.J.Walsh, RNolt, Barry L.[Postharvest root deterioration or vascular streaking of cassava clones (accessions and breeding lines) was evaluated with harvests at different ages (8 and 12 mo.), seasons (beginning and end of wet season), and locations (CIAT-Palmira, Carimagua, and Caribia in Colombia) to assess the effect of environmental factors on cassava genotypes. Vascular streaking was sensitive to any of these environmental factors. Genotype x location interaction was highly significant suggesting that final cv. selection should be carried out in each location. Genetic analysis carried out in one location suggested that inheritance of vascular streaking was, at least partly, controlled by additive factors and was quantitative rather than qualitative. Narrow sense heritability of 0.64 was obtained. Vascular streaking was highly and significantly correlated with root DM content in all the trials conducted during 7 yr. Since free recombination between resistance to vascular streaking and high root DM content may not be possible, the most acceptable balance between these 2 traits should be defined according to the use of product and edaphoclimatic condition of production area prior to selection program. (AS)]Postharvest root deterioration or vascular streaking of cassava clones (accessions and breeding lines) was evaluated with harvests at different ages (8 and 12 mo.), seasons (beginning and end of wet season), and locations (CIAT-Palmira, Carimagua, and Caribia in Colombia) to assess the effect of environmental factors on cassava genotypes. Vascular streaking was sensitive to any of these environmental factors. Genotype x location interaction was highly significant suggesting that final cv. selection should be carried out in each location. Genetic analysis carried out in one location suggested that inheritance of vascular streaking was, at least partly, controlled by additive factors and was quantitative rather than qualitative. Narrow sense heritability of 0.64 was obtained. Vascular streaking was highly and significantly correlated with root DM content in all the trials conducted during 7 yr. Since free recombination between resistance to vascular streaking and high root DM content may not be possible, the most acceptable balance between these 2 traits should be defined according to the use of product and edaphoclimatic condition of production area prior to selection program. (AS)
Autor: Celis, E.

Cassava can be propagated by true seeds and vegetative material. Obtaining true seeds is difficult and resulting plants have longer life cycles, rendering lower tuber production. Thus cuttings are preferred. Recommendations on the optimal length of cuttings vary greatly. Factors involved in using...


Celis, E.[Material de propagacion y siembra de yuca]Material de propagacion y siembra de yuca

Recommendations are given on the var. and cultural practices used in cassava cultivation in the Colombian Llanos Orientales. Initially, soil acidity and low fertility were believed to be the major constraints; however, trials have indicated that diseases (bacterioses, superelongation, and anthrac...


Howeler, Reinhardt H.Ballesteros, D[El cultivo de la yuca en los Llanos Orientales de Colombia: Variedades y practicas agronomicas]El cultivo de la yuca en los Llanos Orientales de Colombia: Variedades y practicas agronomicas

A cassava root harvesting aid was designed that can be attached to a tractor with a hydraulic system. This implement breaks up the soil and loosens the roots, making their manual extraction easy. The aid, as well as the method of operating it, is described and illustrated. (CIAT)


Díaz Durán, Alfonso[Un implemento disenado para ayudar en la cosecha de la yuca]Un implemento disenado para ayudar en la cosecha de la yuca
Sánchez, C.A.Sarria, HArrieta, JROrtega, JJ[Convenio PNR-CIAT. Informe semestral de actividades (Junio- Diciembre 1990)]Convenio PNR-CIAT. Informe semestral de actividades (Junio- Diciembre 1990)
Roca, William M.[Meristem culture in cassava: principles and methodology: principles and procedures]Meristem culture in cassava: principles and methodology: principles and procedures

A survey was made of weed species, weed densities and common weeding practices on 3 visits during the growing season to some 300 farms in 5 cassava-growing regions of Colombia. Broadleaf weeds were the commonest in all regions (62-65 percent of the species); there was a shift to slightly more gra...


Díaz, R.O.Pinstrup-Andersen, PerDoll, J.[Las malezas y su control en el cultivo de la yuca en Colombia]Las malezas y su control en el cultivo de la yuca en Colombia

Approx 20 insects and mites were found attacking cassava in several regions of Colombia at different growth stagcs and seasons. Thrips (Frankliniella williamsi), gall midges (Cecidomyiidae) and whiteflies (Bemisia sp. and Trialeurodes sp.) were present in greater than 50 percent of the plantation...


Díaz, R.O.Bellotti, Anthony C.Schoonhoven, Aart van[Insectos y acaros que atacan el cultivo de la yuca en Colombia]Insectos y acaros que atacan el cultivo de la yuca en Colombia

The supply, availability, and characteristics of cultivated land, cropping systems, yields, socioeconomic profile of producers, production vol., costs, and constraints, and the marketing of root and tuber crops in the Bahamas are analyzed. The internal and external demand of fresh products and th...

Se analizan la oferta, la disponibilidad y las caracteristicas de la tierra sembrada, los sistemas de cultivo, los rendimientos, el perfil socioeconomico de los productores, el vol., costos y limitaciones de la produccion, y el mercadeo de los productos de los cultivos de raices y tuberculos en l...


Smith, Leon S.Swann, GhalyRichardson, Kenneth[Root and tuber crops in the Bahamas]Root and tuber crops in the Bahamas

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