2003 Research Study Report
Watermelon (Citrullus lanatus) seeds and leaves have been found in tombs in Egypt dating back thousands of years. In 1850, explorer David Livingston found wild watermelons in the Kalahari Desert, and thus watermelon is believed to originate in Africa. Watermelons made their way to America with traders four hundred years ago, and the first written record of their cultivation in this country was in Massachusetts in 1629. Today, the United States ranks fourth in the world in watermelon production and in 2002 produced 1.86 million tons of watermelon on 15 million acres, and the crop value was $329 million. The primary watermelon producing states are Texas (26%), Florida (16%) and Georgia (14%). Consumption of watermelon in the United States totaled 3.9 billion pounds in 2000, average per capita consumption was 15.1 pounds, and Asian and Hispanic consumers were the strongest consumer groups. Watermelon is consumed as plain fruit, dessert, fruit salad, snack, picnic food, plate garnish and as a fruit drink.
Watermelons are classified into groups according to fruit shape, rind color or pattern, and weight. These groups are often named after a popular variety with those characteristics (Table 1). Until two decades ago watermelon was only a seasonal fruit, but today imports combined with local production ensure a year-round supply. With a rise in interest in local production and direct marketing, farmers are looking to diversify crop varieties to meet these demands. Icebox watermelons, commonly referred to as mini melons, offer farmers in western Washington a means of producing high quality watermelons locally. Icebox watermelons were introduced to the U.S. marketplace only a few years ago from Asia, and several varieties have very recently been developed and released in the U.S. Icebox watermelons are rapidly gaining popularity, as their smaller size is ideal for small families and for storage in home refrigerators. In 2002 we planted three icebox watermelon varieties to test their production potential at the WSU Vancouver Research and Extension Unit, and based on the success of that study we planted an expanded observation study in 2003 that included 9 varieties.
Table 1. Classification groups of watermelons.
|Group||Shape||Rind Characteristics||Weight (lbs)|
|Jubilee||Oblong||Dark stripes on a light background||25–35|
|Charleston Gray||Oblong||Light green||25–35|
|Allsweet||Oblong||Dark green with light yellow stripe||15–20|
|Royal Sweet or Mirage||Blocky|
|Icebox||Round or Oblong||Yellow to dark green (depending on variety)||8–12|
Icebox Watermelon Study
This observation study (non-replicated) in 2003 included 9 varieties of icebox watermelons grown under drip and overhead sprinkler irrigation systems. The study was conducted on certified organic land and was managed accordingly. The study was funded by the Department of Ecology to measure and demonstrate irrigation efficiency of drip systems as compared to overhead systems, to compare weed control needs under the two irrigation systems, and to provide growers with crop production information to help them diversify farm production. This report will focus on the development of production information for new alternative crops in our region. Icebox watermelons are still new to the marketplace, are grown by only a handful of growers in the region, and seed is only now becoming readily available. Studies are needed to determine maturity dates, total yield, and size and weight of melons grown in the region. Some of the varieties grown in this study are new to the United States and growers may need to specially request seed. The primary objectives of this study were to:
- Measure yield and size of icebox watermelon varieties grown in western Washington.
- Investigate the potential of growing icebox watermelons with drip and overhead sprinkler irrigation systems.
- Evaluate local consumer response to eating qualities of icebox watermelon varieties.
Icebox watermelons were planted in the greenhouse on March 24 and transplanted into the field on June 2. Transplanting was delayed due to wet field conditions in May. Other studies have shown that ideally melons should be transplanted 2-3 weeks after seeding. Plots were one row wide and 15 feet long and spacing between plants was 3 feet. Five plants of each variety were evaluated under both drip irrigation and overhead irrigation systems. Soil in the rows was covered with black plastic, and drip tape was laid under the plastic. In the overhead irrigation system, plants were irrigated once a week at the rate of 1-inch per week from June through August. In the drip irrigation system, plants were due to be irrigated twice a week at the rate of 1-inch per week from June through August, however the drip system malfunctioned for the first two weeks, and plants were extremely stressed and took weeks to recover, and in some cases did not recover. As a result, harvest was delayed in the drip system and in many cases yield was depressed. Thus in this report we will only present yield data for the overhead irrigation system as we feel this more closely reflects potential yield of the varieties.
Icebox watermelons were test-marketed through a local farm store and customers were requested to fill out and return a market questionnaire. All customers paid full price for each icebox watermelon they purchased and those customers who returned a completed questionnaire received a $2 coupon for their next purchase at the farm store. Through this market survey, 280 icebox watermelons were purchased and 56 questionnaires were returned.
Results and Discussion
Icebox watermelon harvest began on August 5, 64 days after transplanting, and continued until October 13 (Table 2). In general, varieties that produced the greatest number of icebox watermelons also generally produced the greatest total yield (Table 3). Orchid Sweet and Sugar Baby were the largest icebox watermelons in the study while Fun Belle and Yellow Doll were the smallest. Dark Belle and Smile produced the greatest number of icebox watermelons and were high yielding, while New Queen produced the fewest number of icebox watermelons and was low yielding (Figures 1 and 2). Icebox watermelon varieties differed in shape and Red Delicious and Dark Belle were oblong while all others were round. Varieties also varied in skin and flesh color: Fun Belle was yellow skinned and red fleshed; Yellow Doll, New Queen and Orchid Sweet and were green skinned and yellow fleshed; all other varieties were green skinned and red fleshed. It was difficult to consistently determine when some varieties in this study reached maturity. Growers will need to test fruit periodically throughout the harvest season to make sure fruit are fully mature and have good eating quality.
Table 2. Icebox watermelon varieties, seed suppliers, harvest dates and the number of days after transplanting to first harvest in a study at WSU Vancouver REU in 2003.
|Variety||Seed Supplier||H. Dates||H DAP|
|Sugar Baby||Abundant Life Seed Foundation||8/5–10/13||64|
Table 3. Total number of fruit harvested, total weight (kg) of fruit harvested, and average weight (kg), length and width per fruit of 9 icebox watermelon varieties.
|Variety||Total No. Fruit Hrv.||Total Wt. (kg)||Avg. Wt. Per Fruit (kg)||Avg. Fruit Length (cm)||Avg. Fruit Width (cm)|
We conducted a market survey at Joe’s Place, a farm store in Vancouver. A photo of each icebox watermelon was displayed and each watermelon was labeled so that customers were certain of the variety they purchased (Figure 3). Icebox watermelons were priced at the market price in Portland (59¢ per pound) and each icebox watermelon cost on average $1.80 or approximately half the cost of a regular large watermelon. Customers were asked to rate on a scale of 1–5 (1=Not important and 5=Very important) whether size, color, price, organic production and novelty played an important part in their decision to purchase icebox watermelons. Customers indicated on average that novelty and color were not important in their purchasing decision while price, organic production and size were more important (Table 4). Customers were also asked to rate on a scale of 1–5 (1=Very poor and 5=Excellent) the flavor, texture, juiciness and overall eating quality of the icebox watermelons. Customers indicated that on average all eating quality aspects of the icebox watermelons were very good, however some varieties were rated higher than others (Table 5). Red Delicious, Dark Belle, Smile and Fun Belle were rated the highest in this study while Sugar Baby and Orchid Sweet were rated the lowest. All customers indicated that the icebox watermelons they purchased were either very easy or easy to store in their refrigerator. Also 60% of the customers indicated they would purchase the same variety again. All customers who purchased Red Delicious and 86% of customers who purchased Fun Belle indicated they would purchase these varieties again, while 75% of customers indicated they would not purchase Orchid Sweet or Sugar Baby again.
Table 4. Customers rated on a scale of 1–5 (1=Not important and 5=Very important) the importance of size, color, price, organic production and novelty in the decision to purchase icebox watermelons in a market survey in Vancouver, Washington in 2003.
|1 Sample number refers to the number of customers who completed a questionnaire.|
Table 5. Customers rated on a scale of 1’5 (1=Very poor and 5=Excellent) the flavor, texture, juiciness and overall quality of the icebox watermelons they tested.
|1 Sample number refers to the number of customers who completed a questionnaire.|
Icebox watermelons can be successfully grown in the field in western Washington and customer surveys indicated that icebox watermelons have good eating quality and are easy to store. Of the 9 varieties we tested, Red Delicious, Dark Belle, Smile and Fun Belle were rated the best quality by customers. Fun Belle was the smallest icebox watermelon in the study while Dark Belle and Smile produced the greatest number of icebox watermelons and were high yielding. Although in this study we experienced mechanical difficulty with our drip irrigation system early in the season, it is evident that drip irrigation can be successfully used to produce icebox watermelons. In 2004 we propose to repeat this study as a replicated field trial and to once again compare drip and overhead irrigation systems.