Researchers at the University of Florida succeeded in using plant grafting to grow seedless watermelons that are more resistant to many soil-borne diseases, even as they retain the fruit quality and flavor. The research will lead to future studies that ensure the fruit will remain resistant in areas of high disease pressure.
Who doesn’t love a juicy watermelon on a hot summer day? Florida is one of the country’s top producers of watermelons, and its business has received a major boon from the research of Xin Zhao, a University of Florida Institute of Agricultural Sciences associate professor. Zhao and her co-authors on a study published in the Journal of the Science of Food and Agriculture used a technique known as plant grafting to produce seedless watermelons that resist common soil-borne diseases while retaining both a strong quality and flavor.
This horticultural technique joins two plants so that they seem to grow as one: the “scion,” or top plant, is grown on top of the “root stock,” or root system, of an entirely different plant.
Seedless watermelons are in high demand, but seedless cultivars appear to be more susceptible to common diseases present in soil, such as fusarium wilt. Using the plant-grafting technique, researchers joined seedless watermelons with squash rootstocks, which are more resistant to many soil-borne diseases. This process carries with it the risk of diminishing the quality and taste of the fruit. However, Zhao’s study revealed no loss in flavor through the use of panels of blind taste testing.
The grafted fruit also did not lose markers of quality, such as total soluble solids – including natural sugars and organic and amino acids – and lycopene content – the naturally occurring chemical that gives watermelons their red color. The total soluble solid content is one of the factors most commonly used in assessing the quality of this fruit. In fact, grafted watermelons had an even higher level of flesh firmness than their non-grafted cousins.
These results are exciting for growers of watermelons. Zhao commented, “We are continuing our grafted watermelon research to optimize management of grafted watermelon production, maximize its full potential and seek answers to economic feasibility.”
Further studies will investigate whether the grafted plants resist fusarium wilt in areas of high disease pressure. Zhao pointed out that there are additionally some challenges with this method of plant grafting: watermelons grafted onto squash rootstocks are more susceptible to root-knot nematodes, roundworms that prey on roots. These nematodes are present in Florida, and they may pose a hurdle to the implementation of the plant grafting technique.
Another team of researchers at UF/IAS is currently addressing these issues. For now, growers may employ the grafting technique in areas plagued by fusarium wilt but relatively low in root-knot nematodes.
This exciting new technique and its developments may well increase yield and raise quality of seedless watermelons in the years to come. While some may be skeptical of these findings as watermelons do not naturally come in seedless form, the research here is clear. If this specific scientific technique can result in fruit that is even better for the system than how it may naturally occur, this is something that we should continue to keep our eye on, and be well aware of.