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Donald E. Irving, Glen J. Shingleton, and Paul L. Hurst

Extractable activities of α-amylase, β-amylase, and starch phosphorylase were investigated in order to understand the mechanism of starch degradation in buttercup squash (Cucurbita maxima Duchesne ex Lam. `Delica') with the ultimate goal of improving the conversion of starch into sweet sugars. During rapid starch synthesis (0 to 30 days after flowering), extractable activities of α-amylase and β-amylase were low, but those of starch phosphorylase increased. After harvest, during ripening at 12 °C, or in fruit left in the field, activities of α-amylase and β-amylase increased. Starch contained 20% to 25% amylose soon after starch synthesis was initiated and until 49 days after harvest irrespective of whether the crop remained in the field or in storage at 12 °C. Maltose concentrations were low prior to harvest, but levels increased during fruit ripening. Data suggest starch breakdown is hydrolytic in buttercup squash, with α-amylase being the primary enzyme responsible for initiating starch breakdown.

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Jake Uretsky and J. Brent Loy

Botwright, T. Mendham, N. Chung, B. 1998 Effect of density on growth, development, yield and quality of kabocha ( Cucurbita maxima ) Austral. J. Expt. Agr. 38 195 200 Broderick, C.E. 1982 Morpho-physiological factors affecting plant productivity in bush and

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María Ferriol, Belén Picó, and Fernando Nuez

Cucurbita maxima Duch. is one of the most morphologically variable cultivated species. The Center for Conservation and Breeding of the Agricultural Diversity (COMAV) holds a diverse germplasm collection of the Cucurbita genus, with more than 300 landraces of this species. Morphological and molecular characterization are needed to facilitate farmer and breeder use of this collection. With this aim, the morphological variation of a collection of 120 C. maxima accessions was evaluated. The majority of these accessions originated from Spain, which has acted as a bridge since the 16th century for spreading squash morphotypes between the Americas and Europe. South American landraces (the center of origin of this species) were also included. Eight morphological types were established based on this characterization and previous intraspecific classifications. A subset of these accessions, selected from these classification and passport data, was employed for molecular characterization. Two marker types were used; sequence related amplified polymorphism (SRAP), which preferentially amplifies open reading frames (ORF), and amplified fragment length polymorphism (AFLP). In the main, SRAP marker analysis grouped accessions in accordance to their type of use (agronomic traits) and AFLP marker analysis grouped accessions as to their geographical origin. AFLP marker analysis detected a greater genetic variability among American than among Spanish accessions. This is likely due to a genetic bottleneck that may have occurred during the introduction of squash into Europe. The disparity of the results obtained with the two markers may be related to the different genome coverage which is characteristic of each particular marker type and/or to its efficiency in sampling variation in a population.

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Yang Chen, Xianzhi Zhou, Yongsheng Lin, and Yucan Zhang

area of 400,000 hm 2 and yielding more than 700 million tons. Furthermore, China is the world’s largest producer of pumpkins ( Yang et al., 2016 ; Zhao et al., 2009 ). Cucurbita moschata , Cucurbita maxima, and C. pepo are the main species in

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Rosa Marina Arvayo-Ortiz, Sergio Garza-Ortega, and Elhadi M. Yahia

Winter squash is grown in the Northwest of Mexico for export to distant markets with risk of produce loss. A study was conducted to investigate its postharvest behavior as affected by hot water (50°C) for 0, 3. 6, 9 and 12 min, and stored at 10 or 20°C with 75% RH for 4, 8, and 12 weeks. The highest weight loss (11.35%) was in fruits without hot water treatment stored at 20°C for 12 weeks; at this temperature the weight loss was 3.65, 7.18, and 10.19% in the 4, 8 and 12 week storage period, respectively. At 10°C the weight loss was 3.41, 6.83 and 7.56% for the same period. Chlorophyll content decreased as temperature and storage period increased. β-carotene content showed no change at 10°C, but slightly increased after 8 and 12 weeks at 20°C. Fruits showed decay by Rhizopus and Aspergillus. Weight loss, chlorophyll content, and decay were not affected by length of hot water treatment. General appearance was better in fruits stored at 10°C than at 20°C.

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Donald E. Irving, Paul L. Hurst, and Jonathan S. Ragg

During this study, we divided the developmental growth pattern of buttercup squash into three phases: 1) early growth, from flowering up to 30 days after flowering; 2) maturation, from 30 days until 60 days after flowering (or harvest); and 3) ripening, from 60 days (or harvest) until ≈100 days after flowering. Harvest occurred at 48 days after flowering. Fruit growth (expansion), starch, and dry matter accumulation were largely completed during early growth, and there was a progressive decline in the respiration rate. Extractable activities of acid and alkaline invertases, sucrose synthase, alkaline α-galactosidase, and sucrose phosphate synthase (assayed with saturating substrates) were high initially but declined markedly during this phase. Glucose, fructose, and low concentrations of raffinose saccharides were present, but no sucrose was detected. During maturation, starch and dry matter remained nearly constant and sucrose began to accumulate. During ripening, starch was degraded, sucrose synthase activity was significant but relatively constant, sucrose phosphate synthase activity increased, and sucrose continued to accumulate.

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M. Ozores-Hampton, H.H. Bryan, B. Schaffer, and E.A. Hanlon

The effects of municipal solid waste (MSW) materials on growth, yield, and mineral element concentrations in tomato (Lycopersicon esculentum Mill.) (1991 and 1992) and squash (Cucurbita maxima Duch. Ex Lam.) (1992 and 1993) were evaluated. Agrisoil compost (composted trash), Eweson compost (co-composted trash and sewage sludge), or Daorganite sludge (chemically and heat-treated sewage sludge) were incorporated into calcareous limestone soil of southern Florida. The control had no MSW material added to the soil. The effect of MSW on crop growth, yield, and mineral element concentrations varied considerably between years for tomato and squash. In 1991, tomato plants grown in soil amended with Eweson or Daorganite had a greater canopy volume than plants in the control treatment. Tomato plants grown in Daorganite had greater total fruit weight (1991) than plants in Agrisoil and more marketable fruit (1992) than control plants. In both years, tomato plants in Agrisoil had higher root Zn concentrations than plants in the other treatments. In 1992, tomato plants in Eweson had lower root Mn concentrations than plants in the other treatments, whereas Mg concentrations in the roots were higher in the Daorganite treatment than in Eweson. Tomato plants in Agrisoil had higher Pb concentrations in the roots than plants in all other treatments. In 1991, leaves of tomato plants in Agrisoil had lower Ca concentrations than leaves of plants in the control treatment. In 1992, leaf Zn concentrations were greater for tomato and squash in Agrisoil than in the control or Daorganite. In 1992, canopy volume and yield of squash were greater for plants in Daorganite than for plants in the control and other MSW treatments. Although canopy volume and total squash fruit weight did not differ among treatments in 1993, plant height was greater for squash plants in the MSW treatments than for those in the control. In 1993, leaf Mg concentrations were greater for squash grown in Daorganite than for plants in the control or Agrisoil. In 1993, fruit Cd concentration was higher for plants with Eweson than for plants in the control or Agrisoil. However, the fruit Cd concentration in squash grown in Eweson compost (1.0 mg/kg dry weight) was far below a hazardous level for human consumption. Our results indicate that amending calcareous soils with MSW materials can increase growth and yield of tomato and squash with negligible increases in heavy metal concentrations in fruit.

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Harry S. Paris and Rebecca Nelson Brown

Pumpkin and squash (Cucurbita L. spp.) are important cucurbit crops and are grown in almost all arable regions of the world. The three economically important species, Cucurbita pepo L., Cucurbita moschata Duchesne, and Cucurbita maxima Duchesne are highly polymorphic in fruit characteristics, inspiring much research into their inheritance. A comprehensive list of genes for Cucurbita was last published more than a decade ago. This new gene list for pumpkin and squash includes descriptions of gene interactions and the genetic background of the parents that had been used for crossing to allow easy confirmation of previous work and provide a sound foundation for further investigation. This gene list includes 79 loci for phenotypic/morphological traits and 48 polymorphic allozyme loci. Linkage and mapping are discussed.

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Anthony P. Keinath and Virginia B. DuBose

Twenty-six cultivars and two numbered selections of Cucurbita pepo L. pumpkin and four cultivars of C. maxima Duchesne pumpkin were evaluated in field experiments in 1996 and 1997 in Charleston, S.C. The four C. maxima cultivars (`Mammoth Gold', `Big Max', `Rouge Vif d'Etamps', and `Lumina') and three C. pepo cultigens (HMX 6686, HMX 6688, and Magic Lantern) had lower powdery mildew [Sphaerotheca fuliginea (Schlechtend.:Fr.) Pollacci] severities than did the other C. pepo cultivars. Overall, C. maxima cultivars also had less foliage showing virus symptoms and less downy mildew [Pseudoperonospora cubensis (Berk.& M.A. Curtis) Rostovzev] than did C. pepo cultigens. Mid- and long-season cultigens of both species (≥100 days to maturity) produced a greater number of marketable-quality fruit than did short-season cultigens. Cucurbita maxima and C. pepo produced similar numbers of marketable fruit; however, more potential marketable yield was possible in C. maxima since most fruit were affected by virus. The C. pepo cultigens Spookie, HMX 6686, and Spooktacular produced the greatest numbers of marketable fruit. In general, no cultigens were well-adapted to the growing conditions of the humid coastal plain of the southeastern United States.

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Rosa Marina Arvayo-Ortiz, Sergio Garza-Ortega, and Elhadi M. Yahia

Winter squash are grown in northwestern Mexico for export to distant markets. During transport, fruits deteriorate and develop fungal rots. Squash (Cucurbita maxima Duch. `Delica') was given hot-water dips at 50C for 0, 3, 6, 9, and 12 min and stored at 10 and 20C with 75% RH for 4, 8, and 12 weeks. The highest weight loss (11.3%) was in fruits without hot water treatment stored at 20C for 12 weeks—weight losses were 3.6%, 7.2%, and 10.2% in the 4-, 8-, and 12-week storage periods, respectively. At 10C, the weight losses were 3.4%, 6.8%, and 7.6% for the same periods, respectively. ß-carotene content increased from 36.2 to 54.2 mg/100 g after 4 and 8 weeks of storage, respectively, but declined to 42.8 mg/100 g after 12 weeks. Chlorophyll content decreased as temperature and storage period increased, changing from 16.7 to 10.8 mg·liter-1 at 10 and 20C and from 16.9 to 15.8 mg·liter-1 and 8.8 mg·liter-1 at 4, 8, and 12 weeks, respectively. Fruits had decay caused by Rhizopus and Aspergillus. Weight loss, ß-carotene and chlorophyll contents, and decay were not affected by length of hot-water treatment. General appearance was better in fruits stored at 10 than at 20C.