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Cassava Genotypes (cassava + genotype)
Selected AbstractsChanges in total carotenoid content at different stages of traditional processing of yellow-fleshed cassava genotypesINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 12 2009Busie Maziya-Dixon Abstract The changes in content of total carotenoid at each stage of processing cassava storage roots were investigated with three improved yellow-fleshed cassava varieties (TMS 94/0006, TMS 01/1235 and TMS 01/1371) grown in 2005/2006 in a randomised complete block design with two replications at Ibadan, Nigeria. When the cassava roots were grated to a mash, results obtained indicate that there was a significant reduction in total carotenoid content for all the genotypes. The reduction was highest for TMS 01/1235 (1.20 ,g g,1), intermediate for TMS 01/1371 (0.78 ,g g,1) and least for TMS 94/0006 (0.35 ,g g,1). In most cases, we observed higher total carotenoid concentration, especially when the intermediate step involved pressing to remove excess water, and during roasting compared with the initial concentration in the raw cassava storage roots. In conclusion, grating, drying and cooking to a paste resulted in reduction of total carotenoid content, while roasting and pressing resulted in higher carotenoid concentration. A change in total carotenoid content during processing depends on variety, processing method, especially unit operation and the initial total carotenoid content of the variety. [source] Environment and host-plant genotype effects on the seasonal dynamics of a predatory mite on cassava in sub-humid tropical AfricaAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 3 2009Christine Zundel Abstract 1,In tropical dry seasons, survival of small arthropods such as predatory mites is often negatively affected by low relative humidity (RH). For species that do not diapause or migrate to refuges, the ability of the habitat to mitigate climatic conditions becomes crucial. 2,The relative effect of macro-habitat (dry grassland hill, humid multiple cropping area, humid riparian forest) and microhabitat (host-plant genotypes with hairy, semi-hairy and glabrous apices) on the seasonal dynamics of the phytoseiid mite Typhlodromalus aripo, a predator of Mononychellus tanajoa on cassava, was examined in a field experiment during a dry season. The effect of RH and plant genotype on T. aripo egg survival was determined in an environment control chamber. 3,Predator abundance was higher in humid multiple cropping areas and on hairy cassava compared with the other habitat types and cassava genotypes. 4,Discriminant and regression analyses showed that the predator's dry season persistence was related to high RH, high plant vigour and hairy apices, but not to prey abundance. 5,In the controlled climate experiment, the effect of host-plant morphology was evident only at the intermediate RH level of 55%. An effect of apex hairiness was not found. 6,It is concluded that the effect of genotype on T. aripo persistence diminishes under low RH conditions, and that supportive effects of apex hairs become effective only in the field, probably through protection from wind and/or intraguild predation. Humid multiple cropping areas planted with hairy and vigorous cassava genotypes are suitable dry season reservoirs for T. aripo. [source] Cassava root yields and culinary qualities as affected by harvest age and test environmentJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 4 2003Jacob M Ngeve Abstract Five cassava genotypes were grown at five contrasting sites in Cameroon, and their roots were harvested 6, 8, 10, 12, 14 and 16 months after planting, to determine the effects of growing environment and harvest age on storage root yields and culinary qualities. The highest root yields were obtained at Ekona (26.3,t,ha,1), whereas the highest root counts were recorded at Bertoua (33 roots per 10,m2). Root yields were lowest (2.9,t,ha,1) when roots were harvested at 6 months, but continued to bulk up to 18.5,t,ha,1 at 16 months. The greatest root increase (9.3,t,ha,1) was observed between 8 and 12 months. Improved and local varieties had comparable dry matter contents (39%). All clones cooked when harvested at 6 and 8 months; thereafter, improved clones did not cook, and cooking duration continued to increase even for the local variety, accounting for the difficulty seen in disseminating these newly developed clones to growers. Cooking durations of roots were longer at Nkolbisson, Bertoua and Ebolowa than at Ekona and Yoke. Soil carbon content was negatively correlated (r,=,,0.999***) with mealiness but not with cooking duration. Cooking quality appears to be under genetic and environmental control. Further studies to elucidate the role of the environment on cookability should concentrate on duration of the rainy and dry seasons, soil physical and chemical properties, and starch chemistry of the genotypes. Suggestions for further research are discussed. © 2003 Society of Chemical Industry [source] Symptom severity of cassava mosaic disease in relation to concentration of African cassava mosaic virus in different cassava genotypesPLANT PATHOLOGY, Issue 1 2003F. O. Ogbe The concentration of African cassava mosaic virus (ACMV) was assessed by enzyme-linked immunosorbent assay in relation to symptom severity among resistant, moderately resistant and susceptible cassava genotypes. Resistant genotype NR 8083 had significantly lower symptom severity scores (P < 0·05) than the susceptible genotype TMS 91934, but the two genotypes contained similar levels of virus concentration. The moderately resistant genotypes TMS 30572 and NR 8082 expressed significantly lower symptom severities (P < 0·05) than the susceptible genotypes TMS 91934 and TME 117, but they contained significantly higher virus concentrations (P < 0·05) than TMS 91934 and similar virus concentration as in TME 117. However, two other resistant genotypes, TME 1 and TME 8, had low symptom severity scores and virus concentrations. There was significant interaction (P , 0·05) between cropping season and virus concentration in all the genotypes except TMS 30572. The resistant and moderately resistant genotypes that had high virus concentrations sustained storage root yield losses. The severity of symptoms expressed was not necessarily a reflection of the virus concentration in some of the genotypes. In addition to the use of symptom severity scores to group genotypes into resistant classes, it is recommended that virus concentration should also be considered. Genotypes displaying mild symptoms, but with high levels of virus accumulation, could be an important source of inoculum in the spread of ACMV by the whitefly vectors. This suggests that each genotype should be tested for virus accumulation prior to its release to the farmers. [source] | ||||||||||