RESUMO
The sensory quality and the contents of quality-determining chemical compounds in unfermented and fermented cocoa from 100 cacao trees (individual genotypes) representing groups of nine genotype spectra (GG), grown at smallholder plantings in the municipality of Waslala, Nicaragua, were evaluated for two successive harvest periods. Cocoa samples were fermented using a technique mimicking recommended on-farm practices. The sensory cocoa quality was assessed by experienced tasters, and seven major chemical taste compounds were quantified by near infrared spectrometry (NIRS). The association of the nine, partially admixed, genotype spectra with the analytical and sensory quality parameters was tested. The individual parameters were analyzed as a function of the factors GG and harvest (including the date of fermentation), individual trees within a single GG were used as replications. In fermented cocoa, significant GG-specific differences were observed for methylxanthines, theobromine-to-caffeine (T/C) ratio, total fat, procyanidin B5 and epicatechin, as well as the sensory attributes global score, astringency, and dry fruit aroma, but differences related to harvest were also apparent. The potential cocoa yield was also highly determined by the individual GG, although there was significant tree-to-tree variation within every single GG. Non-fermented samples showed large harvest-to-harvest variation of their chemical composition, while differences between GG were insignificant. These results suggest that selection by the genetic background, represented here by groups of partially admixed genotype spectra, would be a useful strategy toward enhancing quality and yield of cocoa in Nicaragua. Selection by the GG within the local, genetically segregating populations of seed-propagated cacao, followed by clonal propagation of best-performing individuals of the selected GG could be a viable alternative to traditional propagation of cacao by seed from open pollination. Fast and gentle air-drying of the fermented beans and their permanent dry storage were an efficient and comparatively easy precondition for high cocoa quality.
Assuntos
Cacau/genética , Variação Genética , Árvores/genética , Biflavonoides/análise , Biodiversidade , Biomassa , Cacau/química , Cacau/crescimento & desenvolvimento , Cafeína/análise , Catequina/análise , Fermentação , Manipulação de Alimentos/métodos , Frutas/química , Frutas/genética , Frutas/crescimento & desenvolvimento , Genótipo , Nicarágua , Proantocianidinas/análise , Controle de Qualidade , Sementes/química , Sementes/genética , Sementes/metabolismo , Espectroscopia de Luz Próxima ao Infravermelho , Paladar , Teobromina/análise , Árvores/química , Árvores/crescimento & desenvolvimento , Xantinas/análiseRESUMO
Significant cocoa production in the municipality of Waslala, Nicaragua, began in 1961. Since the 1980s, its economic importance to rural smallholders increased, and the region now contributes more than 50% of national cocoa bean production. This research aimed to assist local farmers to develop production of high-value cocoa based on optimal use of cacao biodiversity. Using microsatellite markers, the allelic composition and genetic structure of cacao was assessed from 44 representative plantings and two unmanaged trees. The population at Waslala consists of only three putative founder genotype spectra (lineages). Two (B and R) were introduced during the past 50 years and occur in >95% of all trees sampled, indicating high rates of outcrossing. Based on intermediate allelic diversity, there was large farm-to-farm multilocus genotypic variation. GIS analysis revealed unequal distribution of the genotype spectra, with R being frequent within a 2 km corridor along roads, and B at more remote sites with lower precipitation. The third lineage, Y, was detected in the two forest trees. For explaining the spatial stratification of the genotype spectra, both human intervention and a combination of management and selection driven by environmental conditions, appear responsible. Genotypes of individual trees were highly diverse across plantings, thus enabling selection for farm-specific qualities. On-farm populations can currently be most clearly recognized by the degree of the contribution of the three genotype spectra. Of two possible strategies for future development of cacao in Waslala, i.e. introducing more unrelated germplasm, or working with existing on-site diversity, the latter seems most appropriate. Superior genotypes could be selected by their specific composite genotype spectra as soon as associations with desired quality traits are established, and clonally multiplied. The two Y trees from the forest share a single multilocus genotype, possibly representing the Mayan, 'ancient Criollo' cacao.
Assuntos
Cacau/genética , Genética Populacional , Biodiversidade , Cacau/economia , Efeito Fundador , Estruturas Genéticas , Variação Genética , Genótipo , Repetições de Microssatélites , Nicarágua , Árvores/genéticaRESUMO
Based on experimental work and a literature surveyy, a comprehensive review of the reproductive biology of coca (Oxalis tuberosa Molina) is presented. Oca was found to be an allogamous tristylous species with some self-incompatibility breakdown, particulary observed in mid-styled genotypes. Seed set obtained from controlled pollinations and pollen fertility data suggest that stylar products interacting with pollen tube growth prevent seed set in illegitimate crosses rather than morphological features of the stigmatic surfaces and pollen grains as suggested in the literature. Pollen size was found to be hhighly variable within anthers of the same level and between levels. A previously unreported mid-style flower morph, with longer styles than those normally found in mid-styled genotypes, as well as a corresponding new stigma shape are reported for the first time. Results are discussed in relation to the pssibility of complenting clonal oca germplasm conservation with sexual seed.
Se presenta una revisión detallada de la biología reproductiva de Oxalis tuberosa Molina basada en trabajos experimentales y en la literatura. Se encontró que la oca es una especie alógama tristílica con ciertas fallas en un sistema reproductivo autoincompatible, especialmente en los genotipos mesostilos. Los datos obtenidos de la polinizaciones dirigidas y de los ensayos de estimación de la fertilidad del polen sugieren que la producción de semillas en cruce ilegitimos es prevenida por la acción de productos estilares interactuando con el desarrollo de los tubos polínicos en los estilo. Contrariamente a lo sugerido en la literatura, se descarta la intervención de características morfológicas de la superficie de los estigmas y de los granos de polen. Se encontró una gran variabilidad en el tamaño de los granos de polen entre anteras de un mismo nivel y entre los diferentes niveles. Se incluye el primer informe sobre la existencia de flores mesostillas con estilos más largos que aquellos encontrados normalmente en los genotipos mesostilos con estilos mas largos que aquellos estigmas. Los resultados son discutidos en relación a la posibilidad de conservar el germoplasma de la oca en forma de semilla sexual.
Assuntos
Fertilidade , Reprodução , Solanum tuberosum , Tubérculos , Ecossistema Andino , EquadorRESUMO
This is a preliminary genetic ecophysiologic study of the maca. Data is presented on the cromosome numbers and genetic variabiity, the bbiological cycle, the use in traditional agriculture and the productivity in its natural habitat. Nutritional and medicinal values are discurred.
En el artículo, los autores ofrecen una primera aproximación al estudio genético-ecofisiológico de la maca (Lepidium meyenii W.). Se consigna información respecto a número cromosómico y variabilidad genética existente; al ciclo biológico, al manejo agronómico tradicional y a los rendimientos en su habitat natural. Igualmente, se llama la atención sobre las propiedades nutritivas y medicinales, que le atribuyen los pobladores de la sierra central del Perú.