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John P. Navazio and Jack E. Staub

Two experiments (1989 and 1990) were designed to characterize the response of cucumber (Cucumis sativus L.) plants with different leaf types [normal leaf (LL) vs. little leaf (ll)] to high soil moisture tension (SMT) and to determine whether hydrocooling would reduce the severity of pillowy fruit disorder (PFD). Comparisons were made among nine cultivars (7 LL and 2 ll) for aboveground vegetative and fruit response, and between two irrigation regimes. High SMT generally caused increased wilt ratings and stomatal conductance and decreased plant dry weight. PFD severity of fruit from watered plots was less [61% (Expt. 1, 1989) and 26% (Expt. 1, 1990)] than of fruit harvested from plots in which water was withheld. The response of the two ll cultivars to moisture stress differed depending on environmental conditions. Increased PFD severity was associated with increased temperature, lower relative humidity (RH), and excluding hydrocooling during postharvest handling. Of the four storage treatments examined, hydrocooling to ≈8.5C then storage at 15C and 85% RH for 4 days produced fruit with the least PFD symptoms. Fruit of `Carolina' (LL) exhibited the highest PFD ratings, while those of `Calypso' (LL) were consistently low compared to other cultivars. Processors can lower PFD incidence and severity by ensuring that adequate moisture is available to plants during fruit enlargement and that harvested fruit are hydrocooled before shipping and storage.

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Byron L. Frenz and Jack E. Staub

During winter months, a substantial volume of various horticultural products are imported to the United States from the Caribbean and Central and South America. United States cucumber (Cucumis sativus L.) processors who market fresh-pack and refrigerated products require raw product daily to meet consumer demands. Mexico serves as a single-source supplier to all United States processors during this period, and thus Mexican production represents certain price risks. United States processors would consider other growing regions to reduce these risks if financially attractive alternatives could be identified. Therefore, a project was initiated to acquire information on production and export costs in Hispaniola (Dominican Republic and Haiti), and to compare those to Mexican and United States production and transport costs. Experimentation lead to the identification of the critical influences of market prices, costs and conditions for the financial feasibility of establishing a processing cucumber industry on Hispaniola. Comparative evaluation indicated that significant variation in total cost was caused by fluctuations in transport, tariffs, and labor cost components. The causes of variation in transportation costs were distance, method (sea, air, truck), competitive demand (volume), and shipping frequency, consistency, and capacity.

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Byron L. Frenz and Jack E. Staub

Development projects in developing countries are generally considered to be speculative investments. Potentially significant returns on investment opportunities are often overlooked by assuming that investment risks in developing countries are greater or less manageable than the risks of investment in developed countries. An import purchasing-risk evaluation identified the costs associated with the production and export of processing cucumbers (Cucumis sativus L.) from Hispaniola (Haiti and the Dominican Republic) to the United States. Although production and export analyses suggested that Hispaniola might not replace Mexico as the primary source of cucumbers for processing in the United States between November and April, Hispaniola affords the U.S. processing industry with an alternative investment option for reducing single-sourcing raw product risk. Therefore, an import diversification evaluation was conducted using Monte Carlo simulation to define a investment-risk model. Monte Carlo simulations of the means and variances of the components of cost andprice were used to assess investment risk under various investment strategies. This model identified sources of cost variation which were then used to characterize export risks derived from growing processing cucumbers on Hispaniola. It was determined that U.S. processors can reduce overall purchasing-risk by diversifying Mexican production to Hispaniola. Through the creation of a strategic transportation alliance between the U.S. and Hispaniola project participants, the export-import costs were such that the investment-risk model identified the allocation of 80% of the production in Mexico and 20% in Haiti as the most favorable diversification strategy. This strategy offered less risk and greater potential long-term returns than purchasing cucumbers solely in Mexico.

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Jack E. Staub and Isabelle Y. Delannay

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Jack E. Staub and Isabelle Y. Delannay

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Michael E. Compton, Brenda L. Fuchs and Jack E. Staub

Cucumis hystrix Chakr. is a rare cucurbit species native to Asia. The species is valued by breeders because of its multiple branching habit and has been used in interspecific crosses with Cucumis sativus. However, individual C. hystrix plants have not been identified in the wild since 1990. Therefore, it was our objective to develop a micropropagation protocol that would allow us to clonally propagate plants in cultivation. Shoots tips (2 cm) were excised from a single C. hystrix plant grown in the greenhouse. All tendrils and leaves were removed before surface-sterilization in 1.25% NaOCl for 5 or 10 min and rinsed six times with sterile distilled water. Shoot tips were trimmed to 1 cm (meristem with two to three young leaf primordia) and placed into 25 × 125-mm test tubes containing 25 ml of initiation medium [MS plus (per liter) 100 mg inositol, 30 g sucrose and 5 g Agargel; pH 5.7-5.8]. PGR combinations tested were initiation medium with 1 μM BA, and initiation medium with 1.7 μM IBA, 0.5 μM kinetin and 0.3 μM GA3 (IKG). Explant survival was greater when shoot tips were surface-sterilized for 5 min (75%) compared to 10 min (33%). More axillary shoots formed when shoot tips were cultured in IKG medium (10.8) than in medium with BA (5.5). Shoots were considerably longer (10 mm) when cultured in medium with IKG compared to BA (1.5 mm). About 64% of shoots place in medium containing 8 μM NAA formed roots and were acclimatized to greenhouse conditions.

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Jack E. Staub, James D. McCreight and Juan E. Zalapa

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Jack E. Staub, Philipp W. Simon and Hugo E. Cuevas

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Zhanyong Sun*, Richard L. Lower and Jack E. Staub

The incorporation of genes for parthenocarpy (production of fruit without fertilization) has potential for increasing yield in pickling cucumber (Cucumis sativus L.). The inheritance of parthenocarpy in cucumber is not well understood, and thus a genetic analysis was performed on F3 cross-progeny resulting from a mating between the processing cucumber inbred line 2A (P1, gynoecious, parthenocarpic, indeterminate, normal leaf) and Gy8 (P2, gynoecious, non-parthenocarpic, indeterminate, normal leaf). A variance component analysis was performed to fruit yield data collected at two locations (designated E-block and G-block) at Hancock, WI in 2000. The relative importance of additive genetic variance compared to dominance genetic variance changed across environments. The additive genetic variance was 0.5 and 4.3 times of dominance genetic variance in E-block and G-block, respectively. The estimated environmental variance accounted for ≈90% of the total phenotypic variance on an individual plant basis in both locations. Narrow-sense heritability estimated on an individual plant basis ranged from 0.04 (E-block) to 0.12 (G-block). Broad-sense heritability estimated on an individual plant basis ranged from 0.12 (E-block) to 0.15 (G-block). The minimum number of effective factors controlling parthenocarpy was estimated to range between 5 (G-block) to 13 (E-block). These results suggest that the response to direct selection of individual plants for improving parthenocarpy character will likely be slow and difficult. Experiment procedures that minimize the effect of environment on the expression of parthenocarpy will likely maximize the likelihood of gain from selection.