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Penelope F. Measham, Audrey G. Quentin, and Nicholas MacNair

Orchard management practices have the potential to influence carbohydrate supply to storage organs, including buds. This study was designed to assess if bud carbohydrates could be manipulated by orchard practices in sweet cherry (Prunus avium). Additionally, we investigated the impact of any such changes on subsequent bud burst and fruit quality the next season. We examined the effect of pruning at different fruit growth stages and cropload on summer and winter bud non-structural carbohydrates (NSCs) and on fruit quality at harvest the next summer in two cultivars. Buds were collected postharvest in summer and after the onset of dormancy in winter, and individual soluble sugars and starch were extracted. The next growing season, flower number and fruit set were recorded. When fruit reached full maturity, fruit were harvested for quality assessment. We observed qualitative changes in NSCs from buds collected in summer and winter. Pruning significantly reduced available NSCs in late summer buds but made little difference by winter; only early pruning showed slight changes in sucrose and glucose. However, early pruning positively influenced the next season’s fruit grade. High cropload resulted in higher NSCs in winter buds than the low cropload. Significant changes in sucrose from summer to winter were observed, and levels of sucrose in the buds differed between cultivars. Different levels of winter bud sucrose between cultivars corresponded to different rates of bud burst. Although pruning was able to manipulate NSCs in buds within a few weeks, these changes were not sufficient to influence the rate of bud burst within a cultivar, but pruning did influence fruit quality in the next season.

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S. Alan Walters

Mini triploid (seedless) watermelons (Citrullus lanatus) are a growing segment of the U.S. watermelon market due to their small, one-serving size. Although mini triploid watermelons were first released and commercially grown about 6 years ago, little information is available for optimum planting densities that are needed to achieve the greatest percentage of marketable fruit in the 3- to 8-lb range. In 2006 and 2007, the fruit grade distribution response to six plant densities (2489, 3111, 4149, 6223, 8297, and 12,446 plants/acre) of four mini watermelon cultivars (Betsy, Petite Treat, Valdoria, and Vanessa) was measured at the Southern Illinois University Horticulture Research Center in Carbondale. ‘SP-1’ was used as the in-row pollenizer at 25% of the total planting. Although all cultivars responded similarly to the plant densities evaluated, ‘Vanessa’ provided the greatest fruit number and weight per acre, and percentage of fruit in the mini grade, compared with the other cultivars. Marketable mini triploid watermelon yield dramatically increased with closer in-row spacings. At lower plant densities (wider in-row spacings), a greater proportion of icebox-sized fruit (>8 lb) was produced, and the amount of marketable, mini-sized fruit (3–8 lb) declined. The grade distribution of mini triploid watermelon numbers and weights were the greatest at the highest plant density evaluated [0.5 ft in-row spacing (12,446 plants/acre)], with about 80% of the total yield in the mini grade. The greatest net revenues were also obtained at this high density. This study indicated that it is critical for producers of mini triploid watermelons to recognize the dramatic impact that plant density has on marketable fruit yield (3–8 lb). Growers of mini triploid watermelons will see a drastic improvement in revenues with closer in-row spacings compared with the approximate 2 ft in-row spacings currently used (about 4000 plants/acre). The increased cost of higher plant densities are more than offset by the greater return on investment.

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Stephen S. Miller and George M. Greene II

In many years, apples grown in the mid-Atlantic region fail to exhibit a high percentage of the dark red color that buyers and consumers desire. In 1996, we initiated studies to examine the use of a metalized silver low-density polyethylene reflective groundcover (RGC) to improve red color on several apple cultivars under several training systems. A RGC placed in the orchard drive middle of 8-year-old `Delicious' apple trees trained to a “Y” trellis increased the percent surface red color and resulted in darker, more red-colored apples at harvest. A RGC increased surface red color on `Empire' apples on a “Y” trellis, but on central leader-trained semi-dwarf and standard size `Empire' showed no effects on color. Central leader-trained `Fuji'/EMLA.7 apples with a RGC had more red color than untreated fruit at harvest. In 1997, RGC placed under the canopy of 3-year-old `Fuji' trees trained to a “Y” trellis increased the full sunlight on the underside of the canopy by 28%. Ambient air temperatures within the RGC illuminated canopy averaged 2.1 °C higher than the non-RGC canopy. The level of percent full sunlight was increased within the canopy of well-pruned 32-year-old `Miller Spur Delicious' apple trees 4- to 8-fold with RGC placed in the row middle or under the canopy in a commercial orchard in 1998. Position of the RGC to the canopy affected fruit red color response differently between the lower and upper part of the canopy. Bins of fruit graded with a commercial color sorter showed no difference in fruit color; however, there was a strong trend toward increased red color where the RGC material was applied.

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Mathieu Ngouajio, Rafael Auras, R. Thomas Fernandez, Maria Rubino, James W. Counts Jr, and Thitisilp Kijchavengkul

Removal and disposal of polyethylene mulch in vegetable production represents a high economic and environmental cost to society. This study was conducted in 2006 and 2007 at Michigan State University to test the field performance of new biodegradable mulches using ‘Mountain Fresh Plus’ tomato (Solanum lycopersicum) as a model crop. Treatments included two biodegradable mulches (black and white), each with two thicknesses (35 and 25 μm). A conventional low-density polyethylene (LDPE) mulch of 25 μm was included as a control (a mulch commonly used by vegetable growers). Data loggers were installed 2 cm into the soil under the various mulches to record soil temperature. The experiment used a randomized complete block design with four replications. The mulches were used on a raised bed, drip irrigation system. Mulch degradation, soil temperature, tomato growth, weed density, and biomass were assessed during the seasons. Tomatoes were harvested at maturity and were fruit graded according to market specifications. Results indicate that soil temperature under the biodegradable mulches was greater than that under the LPDE mulch during the first week. Starting the second week, soil temperature dropped gradually under all the biodegradable mulches. The drop in temperature was greatest with the white mulch. Due to premature breakdown of the white mulches, weed pressure was high, resulting in smaller plants with low yield in 2007. Tomato growth, yield, and fruit quality from the black mulch was equivalent to that in the LDPE mulch. Future studies will optimize biodegradability of the mulches and test mechanical laying of the black mulch under commercial production.

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

immature fruit (grade size 1a-2b) indicated that orange color hue varies depending on greenhouse-growing conditions (unpublished data). The mean and se of mesocarp β-carotene content of mature EOM 402-10 greenhouse-grown fruit is 2.72 μg·g −1 ± 1.15 of

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Matt A. Rudisill, Bruce P. Bordelon, Ronald F. Turco, and Lori A. Hoagland

Tukey adjusted least-square means when the ANOVA F-test was statistically significant ( P ≤ 0.05). Results Yield and fruit grades. In 2011, chard yield was greater in the open field than the high tunnel ( Table 1 ), and yield was greater in the urea

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Qi Sun, Xingnan Zhao, Lei Wu, Jimin Zhao, Yunfei Yang, and Yanwen Zhang

positively correlated with the seed number, single fruit weight, and fruit grade of ‘Bluecrop’ blueberry ( Burd, 1994 ; Dogterom, 1999 ; Dogterom et al., 2000 ; Hoffman et al., 2018 ). For example, a positive relationship between the seed number per fruit

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David H Suchoff, Frank J. Louws, and Christopher C. Gunter

samples (n = 8 data points for each mean); RM = ‘Red Mountain’ nongrafted, CG/RM = ‘Red Mountain’ on ‘Cheong Gang’ rootstock, R/RM = ‘Red Mountain’ on ‘RST-04-106-T’ rootstock, S/RM = ‘Red Mountain’ on ‘Shield’ rootstock. Fruit grade sizes are based on on

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-wire cucumber system that reduced start-up costs. This system achieved similar plant growth, fruit yield, and fruit grades as conventional single-head systems on four seedless cucumber varieties/breeding lines. Since transplant costs for the twin-head system are

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Carolina Font i Forcada, Gemma Reig, Christian Fontich, Ignasi Batlle, Simó Alegre, Celia M. Cantín, Iban Eduardo, Joaquim Carbó, Arsène Maillard, Laurence Maillard, and Joan Bonany

electronic fruit grader (MAF RODA, Iberica, Spain). Under our conditions, all seven peach cultivars stood out for their high productivity and good fruit size, regardless of their harvest season ( Table 1 ). Fruit quality. Fruits of all seven cultivars