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Black pod caused by Phytophthora species is a devastating disease of cacao (Theobroma cacao L.) in production regions worldwide. Breeding for cacao genotypes resistant to black pod disease is crucial for sustainable cocoa production and profitability. Although breeding programmes in the past have made considerable efforts in improving resistance of cocoa genotypes with diverse genetic background, the disease continues to cause unacceptable yield losses in cacao production. To understand the mode of inheritance of epicuticular wax on the surface of cocoa pod known to play a major role in resistance to black pod disease, a 6 × 6 full diallel and a M x N (6 × 4) mating designs were used and data was analysed using Griffing’s method I model I approach and the North Carolina design –II approach, respectively. The results of the two mating designs were consistent and showed that epicuticular wax on leaf and pod surfaces of cacao were under the control of additive genetic effects. The non-additive effects were generally much smaller compared to the additive genetic effects. The significant association between GCA estimates of parents and their means indicates that parental values could be used as indicators of progeny performance. The best general combiners for epicuticular wax load on leaf and pod surfaces were Pa7/808, T60/887 and Pa 150. The larger additive components and heritability observed in this study, indicates that pedigree selection could be used to develop cacao cultivars with high amount of epicuticular wax on pod surface to enhance resistance to black pod disease.

Alongside efforts to improve safe management of feces along the entire sanitation chain, including after the toilet, global sanitation efforts are focusing on universal access ‘basic’ services: onsite facilities that safely contain excreta away from human contact. Although fecal sludge management is improving in urban areas, open drains remain a common fate for feces in these often densely-populated neighborhoods in low-income countries. To-date, it is unclear to what extent complete coverage of onsite sanitation reduces fecal contamination in the urban environment and how fecal contamination varies within urban drains across neighborhoods by sanitation status within a city. We assessed how neighborhood levels of environmental fecal contamination (via spatially-representative sampling of open drains for E. coli) varied across four neighborhoods with varying income, type and coverage of household sanitation facilities, and population density in Accra, Ghana. Neighborhoods with very high sanitation coverage (≥89%) still had high (>4 log10 CFU/100 mL) E. coli concentrations in drains. Between-neighborhood variation in E. coli levels among the high coverage neighborhoods was significant: drain concentrations in neighborhoods with 93% and 89% coverage (4.7 (95% CI: 4.5, 4.9) & 4.9 (95% CI: 4.5, 5.3) log10 CFU/100 mL, respectively) were higher than in the neighborhood with 97% coverage (4.1 log10 CFU/100 mL, 95% CI: 3.8, 4.4 log10 CFU/100 mL). Compared with the highest coverage neighborhood, the neighborhood with lowest coverage (48%) also had higher E. coli concentrations (5.6 log10 CFU/100 mL, 95% CI: 5.3, 5.9 log10 CFU/100 mL). Although fecal contamination in open drains appeared lower in neighborhoods with higher onsite sanitation coverage (and vice versa), other factors (e.g. fecal sludge management, animals, population density) may affect drain concentrations. These results underscore that neighborhood-level onsite sanitation improvements alone may not sufficiently reduce fecal hazards to public health from open drains. These findings supporting the need for integrated, city-level fecal sludge management alongside multifaceted interventions to reduce fecal contamination levels and human exposure.

Stem canker caused by Phytophthora palmivora and Phytophthora megakarya is a serious disease of cacao (Theobroma cacao L.). Studies of the genetics of resistance to this disease is important to identify an effective procedure to use in breeding resistant varieties. The objective of this study was to determine mode of inheritance, combining ability and heritability of resistance to stem canker in cacao. A 6 × 6 full diallel mating design was used to generate 36 F1 hybrids which were evaluated for resistance to stem canker with three replications under artificial inoculation with 1 mm2 agar plug taken from actively growing colonies of 10-day old cultures of P. palmivora and P. megakarya. Twelve months later, the canker lesions on outer bark of the stem of the seedlings were measured and the canker lesions inside was also measured after scraping the bark. There were significant (p 50%) of GCA suggest that additive gene effects were more important than non-additive gene effects. The overall direction of results showed that using one of the following parents: P1 (Alpha B36), P4 (T17/524) and P5 (T65/238) as the female produced progenies with better resistance to stem canker disease than when they were used as the male parent. The majority reflected the resistance level of the female parent, suggesting that resistance to stem canker in cacao is influenced by maternal inheritance. Cacao genotypes Alpha B36, T17/524 and T65/238 showed significant negative GCA effects for resistance to stem canker suggesting that these genotypes will transmit the trait to their progenies and therefore recommended for cacao breeding. Narrow sense heritability for stem canker resistance was low indicating large component of dominance effects and influence of environment in inheritance of resistance to stem canker in cacao. However, the very high broad sense heritability (0.99) coupled with large variation within the cacao tree population indicate that progeny testing and within family selection would be appropriate in breeding against stem canker in cacao.

Studies on quantitative genetics of foliar resistance to black pod disease in cacao could inadvertently use cocoa swollen shoot virus (CSSV) infected leaves which could bias the results especially in West Africa where the virus is prevalent. However, effects of CSSV on inheritance and heritability of foliar resistance to Phytophthora species is not known. Choice of an efficient breeding method requires an accurate estimation of genetic effects in selection schemes for foliar resistance to Phytophthora species in cacao. The objective of this study was to investigate the effect of CSSV infection on quantitative genetic parameters of foliar resistance to cocoa black pod disease in a population of 36 F1 hybrids developed by mating six cacao genotypes using a diallel method. The generated F1s and their parents were evaluated for foliar resistance to P. palmivora and P. megakarya using a randomized complete block design (RCBD) with three replications. 1A CSSV and Nsaba CSSV strains were used to infect the cacao genotypes using the patch graft method. The parents chosen showed significant variations for scores of leaf discs after inoculation with P. palmivora and P. megakarya. The leaf disc scores of CSSV infected crosses were lower than leaf disc scores of CSSV-free crosses. Genetic component analysis showed that the effects of GCA and SCA was significant for both CSSV-free and CSSV-infected crosses in resistance to P. palmivora and P. megakarya. The significant GCA and SCA for both CSSV-free and CSSV-infected crosses strongly suggest that both additive and non-additive genetic effects play an important role in the determination of inheritance of foliar resistance to Phytophthora species in cacao. There was significant variability in mean squares of GCA and SCA of CSSV-free and CSSV-infected crosses indicating that CSSV infection modifies GCA and SCA of affected plants. Narrow sense heritability was relatively low (0.31) for foliar resistance to P. palmivora and P. megakarya under CSSV-free and 1A CSSV strain infected conditions. However, heritability for foliar resistance to P. palmivora (0.43) and P. megakarya (0.36) was significantly higher under Nsaba CSSV infected condition. The modifications of mean squares of GCA and SCA and narrow sense heritability due to CSSV infection could mislead in choice of breeding methods indicating that attention must be paid to the infection status of plants when conducting quantitative genetics studies using diseased and healthy plants. CSSV status of leaf samples should be known before using them in leaf disc test. Genotypes Pa7/808 and Pound 7 had high negative GCA effects and are promising parents for enhancement of resistance to black pod disease in cacao.

American Journal of Biochemistry and Molecular Biology 3 (1): 20-37, 2013 ISSN 2150-4210/DOI:10.39323/ajbmb.2013.20.37 C 2013 Academic Journals Inc.

International Journal of Plant Pathology, 2012 ISSN 1996-0719/ DOI: 3923/ijpp.2012 C 2012 Kwoledgia Review, Malaysia

Black pod is a major disease of cocoa. Knowledge of the inheritance of resistance to black pod would be important in devising strategies to breed resistant varieties. The mode of inheritance of resistance to black pod disease was investigated using leaf disc, detached pod tests and natural field observation in a 6 × 4 factorial and 6 × 6 diallel mating designs analyzed using North Carolina design-II approach and Griffing’s method II model I approach, respectively. The dominant component was smaller than the additive component for pod lesion size, leaf disc scores and natural field infection. Both general combining ability and specific combining ability (SCA) effects influenced the inheritance of pod lesion number and leaf disc scores suggesting that both additive and non-additive (dominance or epistatic) effects influence the inheritance of resistance to black pod disease. However, SCA effect was not significant for pod lesion size and natural field infection suggesting the importance of additive genes in the inheritance of these traits. The higher heritability of leaf disc scores, pod lesion numbers and pod lesion sizes than the heritability of natural field infection which was almost zero, shows the influence of environment on natural field infection and suggests that ranking of resistance of cocoa genotypes need to be done under controlled environmental conditions to observe true resistance levels. Good general combiners, in combination with each other, did not necessarily yield good specific combinations suggesting that parents’ performance cannot be used for selecting superior progenies. The non-significance of reciprocal effects indicates absence of maternal effects or cytoplasmic inheritance in resistance to black pod disease. Recurrent selection procedures and inter-crossing aimed at general combining ability would be more suitable for improvement of black pod disease resistance. Cocoa genotypes with good combining ability for resistance to black pod disease such as T60/887, Pa 150, Sca 6, and Pa7/808, identified in this study could be important parents to form base population for such recurrent selection procedures.

International Journal of Plant Breeding and Genetics, 2012 ISSN 1819-3595/DOI: 10.3923/ijpbg.2012 C2012 Academic Journals Inc.

An article published by Asian Network for Scientific Information; International Journal of Botany 8 (1): 13-21, 2012

Improving breeding strategies for adaptation to water-deficit stress is an important challenge to increasing coffee yields. In a nine-year experiment, 18 genotypes were tested under drought-stress and non-stress conditions to select adaptable genotypes to drought stress. Efficiency of indirect selection based on agronomic traits related to drought-stress was also assessed relative to direct selection based on yield. Drought stress significantly limited fruit-set and yields by 51–75% in all 18 genotypes. Clustering the genotypes based on seven-year average yields under stress and non-stress conditions and their drought susceptibility index (DSI) resulted in the direct selection of eight generally adaptable genotypes. These were characterized by low DSI and high yields in drought-stress and non-stress environments. These genotypes should serve as materials for breeding for drought tolerance or for direct utilization as planting material under drought-stress and non-stress conditions. The first three-year av...

There were significant differences between cocoa genotypes in the levels of blackpod disease in two field trials. Additive (genetic) effects were predominant. The genotypes Pa 150, Alph. B36 and Pound 7 were identified as the best parents for breeding for enhanced resistance to the disease. The performance of cocoa progenies in terms of blackpod disease incidence cannot always be reliably predicted from the genetic potential of their parents. Copyright © 2006 John Wiley & Sons, Ltd

Black pod is an important fungal disease of cocoa (Theobroma cacao L.) that causes severe yield losses. The disease affects the pods, beans, flower cushions, leaves, stems and roots. The objective of this study was to evaluate the efficacy of resistance screening methods used in breeding black pod disease resistance in cocoa. The resistance of cocoa leaves and pods to Phytophthora palmivora was investigated in twenty five international genotypes of cocoa in five laboratory experiments and a field observation at the Cocoa Research Institute of Ghana. A significant clonal difference for leaf and pod resistance was observed at penetration and post-penetration stages of infection. Correlation between resistance of leaves and pods was positive and significant at both penetration and post-penetration stages of infection. The occurrence of such a characteristic of cocoa leaf suggests the value of use of leaves of cocoa seedlings for the prediction of pod resistance to black pod disease. The reliability of the tests was evaluated by correlating results of the inoculation tests with the level of field infection. These correlations were generally positive and significant, both for detached pod and leaf tests. The high positive correlation between detached leaves and pods and natural Phytophthora pod rot infection in the field showed that detached organs can be used for prediction of resistance in the field. Overall, for the convenience of operations and reliability of results, leaf disc test was the best screening method and was also time saving. Clones SCA 6, T85/799, LAF1, ICS 1 and GU 225V were noted to be promising for breeding against black pod disease. The susceptible clones were MO 20, T79/501, VENC 4-4, PA 120 and MOCORONGO.

An experiment was conducted at the Cocoa Research Institute of Ghana (CRIG) to determine if there were any interactions between Phytophthora infection at the distal, proximal and mid-region positions of cocoa pods. The number and size of lesions in nine different cocoa clones were counted and measured at the three different positions of the pod. There were significant differences (p Keywords: Cocoa, Black pod, Phytophthora palmivora, lesions, clones

Developing efficient and reliable screening tests to assess the level of resistance of a perennial crop such as cocoa to diseases is essential to reduce the length of the breeding cycle. The resistance of cacao (Theobroma cacao L.) leaves to two species of Phytophthora was investigated in 25 genotypes of cacao using the leaf disc test. Repeatability of the tests was estimated by calculating the correlation (r) between resistance scores of clones in different inoculation trials of the leaf disc test. Correlations were generally significant (p Keywords: Cocoa, Black pod, Phytophthora, lesions, clones, leaf disc test

Differences were found in the expression of resistance of perennial ryegrass, Lolium perenne, cultivars to crown rust, Puccinia coronata Corda, when plants were incubated at either 10°C or 25°C. In an extreme example, all the genotypes of ‘Carrick’ were resistant at 10°C but susceptible at 25°C. The variation between cultivars was due both to a general increase in expression of susceptibility and the proportion of plants which became susceptible. A BC1 line containing a stay-green gene derived from Festuca pratensis was insensitive to temperature, while a sister line was sensitive.

Cocoa breeding and selection programmes in Ghana and other West African countries have been based largely on existing cultivated populations or on few collections of wild cocoa. The most widely used cocoa germplasm derives from the material collected by F. J. Pound during the periods 1937-1938 and 1942-1943 and distributed as the Iquitos Mixed Calabacillos (IMC), Nanay, Parinari, Scavina, and the Pound series of clones. This material collected in the Upper Amazon region has been particularly successful, suggesting that cacao would be greatly improved if more germplasm material were provided for use by breeders. Maintaining adequate genetic variability in cocoa germplasm collection, essential for sustainable cocoa production, can be realised through active and conscious germplasm acquisition. Because there is the risk of accidentally introducing diseases and pests along with cocoa germplasm material, effective indexing procedures, together with the availability of final quarantine houses in individual producing countries, are essential to ensure that introduced materials are free of diseases and pests. To be successful as breeding material for producing improved varieties for farmers, the introductions must have some desirable characteristics acceptable to chocolate manufacturers and farmers. Les programmes de reproduction et de selection de cacao au Ghana et dans d'autres pays de l'Afrique occidentale ont ete fonde en grande partie sur les populations de cultures existantes ou sur un tous petit nombre de collections de cacao sauvage. Le germeplasme de cacao le plus utilise sur une grande etendue vient de matieres ramassees par F. J. Pound en 1937-1938 et en 1942-1943 et distribuees sous les noms d'Iquitos Mixed Calabacillos (IMC), Nanay, Parinari, Scavina et Pound comme des series de clones. Une succes particulier a ete realise avec cette matiere ramassee de la region de Haute Amazone. Ce succes suggere que meme de plus grandes ameliorations en cacao pourraient etre possible si beaucoup auraient ete disponible pour utilisation par les phytogeticiens. Le maintien de variabilite genetique adequate en collection de germeplasme de cacao est essentiel pour la production durable de cacao et ceci pourrait etre realise par acquisition active et consciente de germeplasme. Puisqu'il y a le risque d'introduire par hasard les maladies et les insectes nuisibles avec la matiere de germeplasme du cacao, les procedures efficaces d'indexation, ainsi que la disponibilite de salles de quarantaine finale dans chaque pay producteur sont essentiel pour assurer que les matietes introduietes sont sans maladies et insectes nuisibles. Pour reussir comme matiere de reproduction pour la production de varietes ameliores pour les agriculteurs, les introductions devraient avoir quelques caracteristiques desirables er acceptables aux fabriquants de chocolat et aux agriculteurs. Ghana Journal of Agricultural Science Vol. 39 (2) 2006: pp. 227