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  • Author or Editor: Harry C. Bittenbender x
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Thirteen coffee genotypes (Coffee arabica) were evaluated for yield stability in fourteen environments within Hawaii. The yield components (fruiting nodes, fruits/node, and fruit size) were also evaluated for stability in four environments. Genotype yield and component were regressed against environmental mean yield and yield component to determine the stability of yield and the components of yield.

Cultivars with means above the grand mean, regression coefficients ≤ 1, and the coefficients of linear determination ≥ 50% were considered to be superior and have phenotypic stability. Stable and superior genotypes are less sensitive to environmental changes and are more adapted to favorable and unfavorable conditions than unstable genotypes.

`Catuai' was stable for both yield and the components of yield (fruiting nodes, and fruits/node) which directly contribute to the yield. The genotype `SL 28' was unstable but highly responsive to favorable environments for yield as well as yield components. Selection for the stability of yield should be considered in coffee breeding programmes to develop genotypes adapted to diverse environmental conditions in Hawaii.

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Application of a kaolin-based particle film, Surround WP, was analyzed using glass plates and slides. The kaolin was sprayed on coffee grown in full sun to evaluate physiological responses to this shading technique. Kaolin reduced photosynthetically active radiation and ultraviolet transmission and decreased surface temperatures on glass slides. In the second year of application, photosynthesis of plants sprayed with kaolin was 71% greater than full-sun plants and yields were doubled. Leaf temperature was significantly lower in the kaolin treatment, but stable C isotope ratios, water use efficiency, nodal growth, and specific leaf area were not. The most likely mechanisms for increased yield are increased light transmittance to inner-canopy nodes or greater storage of photosynthate during the first year. Although results from this study suggest there is much promise for improving the performance and yield of coffee with kaolin application, studies with other species have shown inconsistent results. This inconsistency may be linked to variation in application techniques, kaolin coverage and subsequent effects on light transmission, leaf temperature, and physiological function. Thus, reports on physiological performance alone are insufficient to evaluate the use of kaolin application. Detailed information on application techniques combined with measurements of end-product criteria such as yield or quality are recommended to facilitate cross-study comparisons.

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Standardized and repeatable techniques for microfermentation and drying small samples (<100 g) of cacao (Theobroma cacao), also known as cocoa, are necessary to identify new varieties having high yield and quality. Sensory analyses of the processed cacao seed (bean) are a critical component to develop varieties for Hawaii’s cacao to chocolate industry. A microfermentation and drying system capable of processing multiple samples of mucilage-covered cacao beans ranging from 60 to 6000 g was developed. The effects of fermentation variables, genetic background, management, site, and season on quantitative and qualitative attributes can be studied using this protocol. Beans processed using the College of Tropical Agriculture and Human Resources (CTAHR) bag system (CBS) are inoculated with microorganisms on their fruit (pod) surface. This enables a better assessment of the terroir of sites when the dried fermented beans are roasted and processed. Clean, inexpensive, disposable polyethylene bags serve as fermentation vessels. The fermentery has a temperature controller that follows a fermentation temperature profile. Sun drying is replaced by drying in the laboratory. Two-month storage in ambient outdoor humidity and temperature completes the protocol. The CBS is an improvement to existing cacao microfermentation methods because beans from single pods can be fermented. No microbial isolates, inoculums, or foreign pulp from other trees and sites are used. Less labor is required to maintain the fermentation. In laboratory drying is less variable than sun drying. The CBS is a flexible and reliable method to microferment cacao for scientists, small growers, and hobbyists.

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