Productivity and Characteristics of 23 Seedless Watermelon Cultivars at Three Missouri Locations in 2011 and 2012 Andrew L. Thomas 1, Catherine A. Bohnert 2, Nahshon A. Bishop 2, Steven Kirk 2, Sarah S. Becker 2, Patrick L. Byers 3, Ryan L. Meeks 1,2, Valen J. Tanner 1,2, and Sanjun Gu 2 1 University of Missouri Southwest Research Center, Mt. Vernon 2 Lincoln University, Jefferson City, Missouri 3 University of Missouri Cooperative Extension Service, Springfield This report summarizes results from seedless watermelon [Citrullus lanatus (Thunb.)] trials conducted at three diverse Missouri locations in 2011 and 2012. A total of 23 cultivars from three seed companies were evaluated over the two years; however, not all cultivars were evaluated at all sites both years. Materials and Methods Field trials of seedless watermelon were established in 2011 at the University of Missouri s Southwest Research Center near Mt. Vernon in southwest Missouri (37.07545, -93.879118), and at three Missouri sites in 2012: Mt. Vernon, plus Lincoln University s Carver Farm at Jefferson City in central Missouri (38.528379, -92.138785), and a private farm (Brian Hays) near Malden in the Boot-heel region of southeast Missouri (36.538704, -89.984379). The soils at the three sites are a Creldon silt loam, Freeburg/Hartville silt loam, and Bosket fine sandy loam, respectively. The site in Missouri s Boot-heel is a well-known watermelon-growing region. Twenty-three seedless watermelon cultivars from Abbott & Cobb, Harris Seeds, and Rogers/Syngenta seed companies were chosen for this trial (Table 1). Accomplice and Gladiator were used as pollenizers for the trials in central and southwest Missouri, while Estrella was used as the pollenizer in the Boot-heel. In all cases, seeds were germinated in a greenhouse several weeks before establishing the field trials with transplants. Seeds were direct seeded in 804 inserts filled with BM7 soilless potting media and placed in a greenhouse where temperature was kept at 22-28 C. In 2012, transplants were started from seeds the first week of April for the southwest location, the third week of April for the central location, and in mid-march for the Boot-heel location. Transplants went through a period of hardening before being planted in the field. Test plots were established May 26-27, 2011, and May 8-9, 2012, at the southwest site; May 21, 2012, at the central site; and May 8-9, 2012, at the Boot-heel site. Plants were spaced 3 feet apart within the row in the southwest trials, 3.5 feet apart in the central trial, and 2.5 feet apart in the Boot-heel trial. Rows were 12 feet apart at the southwest site, and 9 feet apart at the Boot-heel and central sites. Raised beds were covered with black plastic, and a single buried drip line was installed in each row in all trials. One pollenizer was planted for every four seedless vines and at both ends of a row to provide pollen. At the southwest and Boot-heel sites, a honeybee hive was located nearby. Vines were fertilized according to standard recommendations, either by fertigation or by hand, and also by foliar feeding in the Boot-heel trial. Two applications of insecticides and three of fungicides were used in the Boot-heel trial, whereas no insecticides or fungicides were used in the southwest and central Missouri trials.
The experiment was conducted as a completely randomized design at each site, with four replications per cultivar and four plants per replication. Harvests were conducted as fruit ripened at the southwest site, July 26-August 3, 2011, and July 3-12, 2012. Single-day harvests were conducted on August 6, 2012, in central Missouri; and on July 17, 2012, in the Boot-heel. Total fruit yields were not determined at the Boot-heel site; however, fruit were harvested from that site to compare their characteristics with fruit from the other sites. All other watermelon fruits were counted and weighed upon harvest. One fully ripe medium-size fruit from each replication plot was selected to determine fruit characteristics, including fruit diameter, fruit length, rind width, and soluble solids concentration ( o Brix) measured with a hand-held refractometer. In 2011, a fruit sensory evaluation was conducted with ripe fruit harvested directly from the southwest Missouri plots. The judges were attendees at a Watermelon Field Day and were not professionally trained sensory analysts. Participants judged taste, aroma, mouth-feel (including seedlessness), outer fruit appearance, and flesh appearance on a 1 to 5 scale with 5 being the best rating. All data were analyzed with SAS 9.3, using the general linear model for variance analyses, and with means separated by Duncan s multiple range test at the P 0.05 level. Results and Discussion Fruit characteristics from the watermelon trials at all three sites in 2012 are presented in Table 2. The Fruit weight column is not necessarily indicative of fruit yields; this is simply the mean weight of the single medium-size fruits evaluated from each replicated plot (up to 12 fruits most cases). No significant differences in fruit diameter or rind thickness were detected among the 16 cultivars or among the three sites. The cultivars Sweet Delight and WDL9408 produced the longest fruits across all three sites (24.1 and 24.0 cm, respectively), whereas Distinction produced the shortest fruits on average (20.6 cm). Soluble solids were highest in Distinction and 7387HQ (both with 12.0 o Brix), whereas Crunchy Red was the lowest at 10.2 o Brix. The majority of cultivars were not significantly different from each other in terms of soluble solids. When comparing fruit characteristics among sites, few differences were detected except that soluble solids were higher overall at the central Missouri site, with a mean of 11.96 o Brix. Detailed fruit yields among 18 cultivars from the central Missouri site in 2012 are presented in Table 3. Numbers of fruits produced among cultivars were not significantly different. The highest yielders were WDL9408 and Buttercup (65.3 and 64.6 lbs from 4-plant plots, respectively), whereas the lowest yielder was Melody with 24.0 lbs from 4-plant plots. Most other cultivars did not produce yields that were significantly different from each other at this location. Summer King produced fruits that were significantly larger than all other cultivars, averaging 14.0 lbs. The smallest fruits were produced by Melody (6.7 lbs), with the other cultivars producing fruits of intermediate size with varying degrees of differences among cultivars. Table 4 summarizes two years of trials using the same 19 cultivars at the southwest Missouri site. Yields in 2011 were significantly greater than yields in 2012. The plots were established 18 days earlier in 2012. Fertilization, irrigation, and management regimens, as well as very hot and droughty conditions were otherwise similar in both years. The same field site was used both years. We did not experience any noticeable disease or pest pressure possibly resulting from using the same site two years in a row. Thus it is difficult to understand or explain why yields
were so much lower in 2012. The plants in 2012 simply seemed to lack vigor compared with plants in 2011. Among the cultivars grown both years at this site, 5244, 7287HQ, and Crispy Red produced the largest fruit yields (by weight) with 104, 102, and 99 lbs per 4-plant plot. The lowest yielding cultivar, which was significantly lower than all other cultivars, was 7387HQ, with only 44 lbs per 4-plant plot. Numbers of fruits per plot followed similar patterns with 5244, 7287HQ, and Crispy Red producing an average of 9.0, 8.9, and 9.0 fruit per 4-plant plot, respectively, with 7387HQ only producing 5.5 fruits per plot. Average fruit weights were significantly highest for Summer Velvet at 14.9 lbs. The smallest fruit were produced by 7387HQ at only 8.2 lbs. Over the two-year study, 7387HQ fruits were the first to ripen (July 9), with 5244 the last (July 19). Once harvest began during both years, it progressed very quickly due to extreme heat conditions and little additional differences in earliness/lateness were discernible. Results from the sensory evaluation of ripe fruits from the southwest Missouri site in 2011 are presented in Table 5. The cultivars with the highest overall rating among all sensory characteristics were 7197HQ, Troubadour, and Summer Velvet, whereas the lowest rated fruits were from Crispy Red. The same 7197HQ and Troubadour had very high results for taste and mouth-feel, whereas Summer Velvet scored higher in both outer fruit and flesh appearance. Crispy Red tended to score low in nearly all categories. Substantial and consistent differences in the performance of specific seedless watermelon cultivars from this two-year, three-site study are difficult to discern. Different cultivars certainly tend to perform differently at different sites and in different years. For example, while Crispy Red produced high yields and large fruits at the southwest site, the sensory evaluations rated that cultivar very low. Troubadour also scored very high in the sensory evaluations but performed average to low in yields and fruit characteristics overall. Nevertheless, the cultivars 5244, 7287HQ, 7197HQ, Summer Velvet, WDL9408, and Buttercup tend to stand out as very promising seedless watermelon cultivars for Missouri.
Table 1. Cultivars used in Missouri seedless watermelon trials 2011-2012, and seed sources. Cultivar Seed Company 35214 7167HQ 7177HQ 7187HQ 7197HQ 7387HQ Crispy Red SS7267 Summer Velvet 5244 Crunchy Red HR Millionaire HR Troubadour HR Buttercup Distinction Fascination Imagination Melody Palomar RWT8231 Summer King Sweet Delight WDL9408 Pollenizers Accomplice HR Estrella Gladiator =Abbott and Cobb Seeds, =Syngenta Seeds Inc., Rogers Brand, HR=Harris Seeds.
Table 2. Productivity and fruit characteristics of 16 seedless watermelon cultivars grown at three Missouri sites, 2012. Cultivar Fruit Weight (lb) Fruit Diameter (cm) Fruit Length (cm) Rind Thickness (cm) Soluble Solids ( Brix) Crunchy Red 11.1 ab 20.0 23.4 ab 1.13 10.2 c Distinction 9.7 b 20.1 20.6 c 1.17 12.0 a Fascination 11.6 ab 20.7 23.6 ab 1.04 11.5 ab Melody 9.7 b 20.1 21.2 bc 1.13 11.8 ab Millionaire 10.2 b 20.2 22.6 abc 1.00 11.8 ab Palomar 11.4 ab 21.2 21.9 abc 1.05 11.8 ab Summer King 11.4 ab 20.2 23.3 ab 0.94 10.9 bc Sweet Delight 13.0 a 21.1 24.1 a 1.03 11.6 ab Troubadour 9.7 b 19.3 22.0 abc 1.01 11.1 ab RWT8231 10.7 ab 20.6 21.2 bc 0.97 11.2 ab WDL9408 12.1 ab 21.0 24.0 a 1.16 11.3 ab 7167HQ 10.8 ab 19.9 22.5 abc 1.07 11.8 ab 7177HQ 9.9 b 20.3 23.1 ab 1.03 11.4 ab 7187HQ 11.3 ab 20.5 22.9 abc 0.93 11.1 ab 7197HQ 11.9 ab 20.8 23.5 ab 0.94 11.7 ab 7387HQ 11.2 ab 20.4 23.1 ab 1.13 12.0 a Site Boot-heel MO 12.1 a 21.0 23.0 a 0.99 11.34 b Central MO 11.4 a 20.8 22.9 a 1.01 11.96 a Southwest MO 9.9 b 19.6 22.2 a 1.13 11.12 b Means within subcolumns with the same letters are not significantly different according to Duncan s multiple range test (P 0.05).
Table 3. Productivity and fruit characteristics of 18 seedless watermelon cultivars grown at Carver Farm in central Missouri, 2012 (figures are means from 4-plant plots). Cultivar Number of Fruit Total Fruit Weight (lb) Average Fruit Weight (lb) Buttercup 6.5 64.6 a 10.1 bcd Crunchy Red 5.8 47.0 abc 8.4 bcde Distinction 6.0 47.9 abc 7.7 bcde Fascination 6.0 54.8 ab 9.1 bcde Imagination 5.0 38.7 abc 8.1 bcde Melody 3.0 24.0 c 6.7 e Millionaire 5.5 52.5 ab 9.8 bcde Palomar 5.3 57.0 ab 10.7 bc Summer King 4.3 59.2 ab 14.0 a Sweet Delight 5.0 46.5 abc 9.2 bcde Troubadour 4.5 31.4 bc 6.7 de RWT8231 4.0 34.4 bc 8.9 bcde WDL9408 6.3 65.3 a 10.4 bc 35214 6.0 45.4 abc 7.6 cde 7167HQ 4.5 47.2 abc 10.2 bc 7177HQ 6.0 51.9 ab 8.9 bcde 7197HQ 4.3 38.3 abc 9.1 bcde 7387HQ 3.8 41.3 abc 10.9 b Means within a column with the same letters are not significantly different according to Duncan s multiple range test (P 0.05).
Table 4. Productivity, fruit characteristics, and harvest dates of 19 seedless watermelon cultivars grown at the Southwest Research Center in southwest Missouri, 2011 and 2012 (figures are means from 4-plant plots). Cultivar Number of Fruit Total Fruit Weight (lb) Average Fruit Weight (lb) Harvest Date Crispy Red 9.0 a 99 ab 11.1 bcdef July 20 def Distinction 7.5 abcde 78 bcd 10.4 ef July 22 bc Fascination 5.9 de 80 abcd 11.9 bcd July 21 cd Imagination 7.0 abcde 69 cd 9.9 f July 20 def Melody 6.3 cde 68 d 10.8 bcdef July 21 de Millionaire 8.2 abc 86 abcd 10.6 cdef July 19 g Palomar 8.5 ab 89 abcd 10.5 def July 20 efg Summer King 7.8 abcd 94 abc 12.1 b July 20 def Summer Velvet 6.3 bcde 93 abc 14.9 a July 20 def Sweet Delight 6.5 bcde 70 cd 10.8 bcdef July 19 g Troubadour 6.6 bcde 69 cd 10.5 def July 23 b 5244 9.0 a 104 a 11.5 bcde July 27 a 7167HQ 8.4 abc 90 abcd 10.8 bcdef July 19 fg 7177HQ 7.9 abcd 86 abcd 10.9 bcdef July 20 efg 7187HQ 7.6 abcde 82 abcd 10.9 bcdef July 21 de 7197HQ 8.2 abc 83 abcd 10.2 ef July 20 efg 7267HQ 8.9 a 90 abcd 10.2 ef July 19 g 7287HQ 8.5 ab 102 ab 12.0 bc July 23 b 7387HQ 5.5 e 44 e 8.2 g July 9 h Year 2011 9.4 a 115.9 a 12.3 a July 28 2012 5.8 b 51.8 b 8.9 b July 9 Means within subcolumns with the same letters are not significantly different according to Duncan s multiple range test (P 0.05).
Table 5. Watermelon sensory evaluation results from seedless watermelons grown at the Southwest Center in southwest Missouri, 2011. Scale was 1-5 with 5 being the best rating. Sorted by overall best rating. Cultivar Overall Rating Taste Aroma Mouth-feel Fruit Appearance Flesh Appearance 7197HQ 3.84 a 4.21 a 3.57 3.86 a 3.80 abcd 3.79 bcdef Troubadour 3.79 ab 3.70 abcd 3.20 3.74 ab 4.04 abc 4.19 ab Summer Velvet 3.72 abc 3.29 cde 3.30 3.43 abc 4.26 a 4.32 a Sweet Delight 3.67 abcd 3.76 abc 3.59 3.65 ab 3.61 bcdef 3.71 bcdef Distinction 3.64 abcd 3.30 cde 3.08 3.56 ab 4.19 a 4.04 abcd 5244 3.61 abcd 3.95 ab 3.30 3.59 ab 3.55 cdefg 3.64 cdef Imagination 3.59 abcd 3.14 ef 3.04 3.45 abc 4.17 a 4.10 abc 7167HQ 3.49 abcde 3.32 cde 3.33 3.57 ab 3.63 bcdef 3.61 defg Fascination 3.46 bcde 3.18 def 3.15 3.54 abc 3.68 bcde 3.71 bcdef 7287HQ 3.43 bcde 3.92 ab 3.32 3.77 ab 3.08 g 3.11 h 7267HQ 3.40 cde 3.19 def 3.15 3.52 abc 3.55 cdefg 3.59 defg 7177HQ 3.39 cde 3.27 cde 3.25 3.42 abc 3.54 defg 3.46 efgh Millionaire 3.37 cde 3.46 bcde 3.27 3.71 ab 3.18 fg 3.21 gh Melody 3.32 def 2.50 g 3.00 2.82 d 4.07 ab 4.18 ab 7187HQ 3.20 ef 3.19 def 3.02 3.36 abc 3.19 efg 3.26 fgh Summer King 3.14 ef 3.33 cde 2.92 3.22 bcd 3.11 g 3.07 h Crispy Red 2.98 f 2.72 fg 2.96 3.00 cd 3.12 g 3.08 h n = 526 n = 524 n = 500 n = 525 n = 524 n = 525 p < 0.0001 p < 0.0001 NS p < 0.0012 p < 0.0001 p < 0.0001 Means within a column with the same letters are not significantly different according to Duncan s multiple range test (P 0.05). NS = non-significant.