Postharvest applications of polyamines reduced chilling injury of McIntosh apples and zucchini squash. McIntosh apples developed brown core, a symptom of chilling injury, after 5 months of storage at 0°C. However, this disorder was absent in fruit infiltrated with putrescine, spermidine, or spermine. Polyamine treatments also reduced softening of fruit tissue. Pressure infiltration of zucchini squash with spermine immediately after harvest reduced the severity of surface pitting during subsequent storage at 2.5°C. The elevation of spermidine and spermine levels and the augmentation of S-denosyl-methionine decarboxylase activity in squash by temperature preconditioning was also correlated with increased resistance of the squash to chilling injury.
C. Y. Wang and G. F. Kramer
S. Alan Walters and Jeffrey D. Kindhart
Various tillage systems were evaluated in summer squash (Cucurbita pepo) production in southern Illinois to observe the influence of these systems on yellow and zucchini squash production during 1998, 1999, and 2000. For squash production, suppression of a cover crop such as tall fescue (Festuca arundinacea) or winter ryegrass (Secale cereale) must be accomplished to obtain the greatest possible yields. However, once the cover crop is killed via herbicides, squash yields tend to be similar among tillage, strip tillage, and no-tillage treatments. Previous studies indicated that early yields may be reduced when using a no-tillage production system, especially if direct seeding is the method of planting and would not be beneficial to growers seeking early production. This study found that squash growers can use transplants in a no-tillage system and not compromise early yields. No differences were observed for soil bulk densities between tillage and no-tillage treatments and may partially explain why similar yields were obtained between these treatments. Effective systems for weed control must be developed in no-tillage squash production before wide acceptance will occur. Observations from this study indicated that the success of no-tillage squash production depends on the availability of effective herbicides; however, few herbicides are currently labeled for use in summer squash. Future studies need to address the problem of weed control in no-tillage squash production.
to vary according to production region and management strategy. This trial was conducted to evaluate the performance of four readily obtainable papers compared with traditional black plastic with a short, warm-season crop (yellow squash) in the
J. M. Schalk, C. S. Creighton, R. L. Fery, W. R. Sitterly, B. W. Davis, T. L. McFadden, and Augustine Day
In field tests, the most effective film mulch in deterring insects and reducing insect damage to fruits was aluminum. The insects affected were aphids, brown stink bugs, aphid parasites, and Diabrotica spp. Mosaic virus diseases were reduced among aluminum-mulched squash (Cucurbita pepo L.) and cucumber (Cucumis sativus L.) plants. Plant growth, flowering, and fruiting were delayed in tomatoes (Lycopersicon esculentum Mill.) and southernpeas (Vigna unguiculata (L.) Walp.).
George F. Kramer and Chien Yi Wang
Prestorage temperature conditioning of zucchini squash (Cucurbita pepo L. cv. Ambassador) at 10 or 15C was effective in delaying the onset of chilling injury (surface pitting) during storage at 2.5 or 5.0C. Intermittent warming in cycles of 2 days of chilling followed by 1 day at 20C was also effective in minimizing surface pitting. One-half of the preconditioned squash stored at 5C still was marketable 16 days after harvest, as compared to only 8 days for the chilled control. Due to its simplicity, temperature preconditioning may have potential to become a commercially important technique for extending the shelf life of zucchini squash.
Oved Shifriss and Harry S. Paris
Data from a cross between ‘Table King’, B +/B +, bearing green fruits, and ‘Precocious Small Sugar’, B/B, bearing yellow fruits, revealed the existence of 2 independent modifier genes, designated Ep-1 and Ep-2, each of which can extend the boundaries of precocious fruit pigmentation conditioned by gene B. The effect of these modifiers of B is cumulative, but the dosage of B plays an important role in controlling the extent of precocious pigmentation. Some commercial hybrids are B/+ and these tend to produce bicolor fruits, an undesirable feature in squash. The present findings suggest that B/+ hybrids can produce yellow fruits exclusively, provided they carry 2 or more Ep genes.
J. Brent Loy
Acorn squash (Cucurbita pepo L.) is one of the three major classes of squash consumed in North America. Breeding improvements over the past 30 years have focused on more compact cultivars, earlier maturity, darker rind color, and powdery mildew tolerance (PMT). Our observations from sampling acorn squash from local supermarkets at different times during the year show that eating quality is highly variable, and most often, not acceptable. Our taste tests indicate that for acceptable eating, quality acorn squash should have °Brix of 10 or higher, flesh %DW above 16, and a smooth, nonfibrous texture. Most commercial cultivars fail to meet the above minimum criteria for quality. Proper harvest time is a major determinant of squash eating quality. To obtain adequate °Brix levels, squash should not be harvested until at least 50 days after pollination (DAP). If squash are harvested between 25 to 40 DAP and then stored for two or more weeks, °Brix levels may increase to acceptable levels, but some mesocarp reserves will be remobilized to developing seeds, reducing mesocarp %DW and lowering eating quality. A major goal of the squash breeding efforts at the University of New Hampshire has been to increase mesocarp %DW for obtaining more consistent eating quality. We have evaluated several experimental PMT hybrids during the past 5 years, and in some of these, flesh DW has averaged 17% or higher, and eating quality has been rated consistently very good. The adoption of better quality acorn cultivars together with implementing proper harvest times and storage conditions could appreciably increase per capita consumption.
Shawna L. Daley and Richard L. Hassell
commonly used in Asia and Europe, bottle gourd ( Lagenaria sicereria cv. Emphasis) (Syngenta Seeds, Boise, ID) and interspecific hybrid squash ( Cucurbita maxima × Cucurbita moschata cv. Carnivor) (Syngenta Seeds), were sown in 72-cell, TLC polyform
Yellow nutsedge (YNS) can be a serious problem where vegetables are grown on polyethylene mulch. YNS will rapidly cover the row and become a nuisance. This study was conducted to determine the effect of various population densities of YNS on the yield response of yellow squash grown on black polyethylene. Presprouted YNS tubers were planted at densities of 0, 10, 20, 40, and 50/m2 the day after `Superpik' yellow squash was planted. In 1996 the YNS did not produce tubers. Top growth increased up to 40/m2, but root growth increased to 50/m2. In 1997 top and root growth increased up to 20/m2. Tuber production increased up to 40/m2. In 1998 top, root, and tubers dry weight increased as the YNS density increased to 50 tubers/m2. There were no differences in weight of the squash plants or fruit yields any year. In experiments over three growing seasons, YNS at the densities tested did not interfere with the yield of yellow summer squash grown on black polyethylene mulch. The rapid growth of the squash and its dense canopy provide too much shade for the YNS to grow competitively. The yield of the YNS was greater in wet years than in dry years. The increased supply of YNS tubers could cause squash yield reductions in future plantings because of potential densities greater than those use in this study. YNS competition could also be a problem in rotational crops that are less competitive.
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.