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  • Author or Editor: Loren D. Gautz x
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Loren D. Gautz and Charles W. Wong

A device is described that can be used to open and close Magenta vessels used for micropropagation. Performance of the device is reported and compared favorably to unassisted manual opening and closing of vessels. Benefits include elimination of a potentially physically damaging (e.g., carpal tunnel syndrome) manual operation.

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Paul N. Walker, Joan P. Harris and Loren D. Gautz

Four engineering studies on optimization of sugarcane micropropagation are summarized. The optimum environmental conditions based on the cost of production were found to be with two medium changes per multiplication period, 6 initial shoots per vessel and a photosynthetic photon flux of 200 μmol/m2s even though greater production was obtained for more light, fewer shoots per vessel and more medium changes. A cost model for comparing production treatments under steady state production and a linear programming model for unsteady state production are discussed. Preliminary results on mechanization of the transfer process are also presented.

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Silvia G. Mauri, H.C. Bittenbender, Kent D. Fleming and Loren D. Gautz

Marketable coffee (Coffea arabica) yield and cost of production under two systems of mechanized pruning—hedging and stumping— were investigated. Data were collected from 1997 to 2001—a single pruning cycle—on three cultivars on three farms on Kauai, Maui, and Molokai. Treatments were variations of hedging and stumping, including time of pruning, methods of re-growth control, and tree in-row spacing were applied to each coffee cultivar. Economic evaluation was based on a partial budget analysis of the actual costs per year of the different pruning systems used on each farm. Mechanical pruning costs per acre for best hedging and stumping treatments across cultivars were 90% and 83% less, respectively, than the current practice of manual pruning. Response to pruning system varied according to coffee cultivar, tree in-row spacing and farm location. The tall cultivar Mokka had higher yields when hedged at 5 ft (1.5 m) tall and 5 ft wide, and the semi-dwarf cultivar Yellow Catuai had higher yields when stumped at 2 ft (0.6 m) tall. Hedge pruning should be done early in the year, January to February, for the semi-dwarfs, `Yellow Catuai' and `Red Catuai', but can be delayed until May for `Mokka'. Annual topping in the hedging systems should be done January to May for `Yellow Catuai' but maybe delayed until May for `Mokka' and `Red Catuai' without yield loss. The economic evaluation revealed that the cost of stumping was higher than hedging. For `Yellow Catuai' on Kauai the economic evaluation indicated that although the cost of stumping was higher, the accompanying higher yields resulted in a higher gross margin for this system. When stumping, verti- cal branches can be set with a contact herbicide spray to avoid higher hand pruning costs without lowering yields. Stumps should be narrowed after stumping if spaced, 2.5 ft (0.75 m) the current standard in-row spacing for mechanical harvesting. Wide in-row spacing (5 ft) should be considered by growers when planting or re-planting.

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Harry C. Bittenbender, Loren D. Gautz, Ed Seguine and Jason L. Myers

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.