Biostimulant Applications in Watermelon Production Evan Christensen, Milena M. T. de Oliveira, Youping Sun, Grant Cardon, and Dan Drost
Introduction Watermelon is a water-intensive vegetable crop that is sensitive to drought and requires an adequate supply of nutrients for good yield and fruit quality. It is an important vegetable crop grown on 142,000 acres in the United States and 586 acres throughout Utah. Utah experienced its driest year on record in 2020 during a five-year drought (2019 to 2023). This affected local ecosystems, such as the Great Salt Lake, which suffered recordlow water levels. The drought also negatively affected the agricultural sector, including watermelon growers. Higher-than-average fertilizer prices in recent years have also threatened watermelon production. Growing awareness of agriculture's water use and its contribution to nutrient pollution in waterways has prompted investigations into reducing water and fertilizer applications to achieve more sustainable watermelon production in Utah. Plant biostimulants have been shown to increase drought tolerance and enhance nutrient efficiency and may be a novel method to combat these challenges.
What Are Biostimulants? Plant biostimulants are any microorganism or substance applied to seeds, plants, or the soil that stimulates natural processes to enhance or benefit nutrient efficiency or uptake, tolerance to stress, or crop quality and yield (Gedeon et al., 2022). Many substances and microorganisms can be considered biostimulants. Similar substances and microorganisms are grouped into major categories (du Jardin, 2015). These include beneficial bacteria and 1
Highlights • • •
• •
•
•
Producers grow watermelon on 586 acres in Utah. Drought and high fertilizer prices have affected watermelon production. Biostimulants are microorganisms or substances applied to seeds, plants, or the soil. Non-biological biostimulants include seaweed extracts and humic products. Adding biostimulants to seeds, plants, or the soil can enhance nutrient uptake, stress tolerance, and crop quality and yield. Short-term applications may be insufficient to show biostimulant benefits according to trials run in Utah. More research is needed before commercial recommendations for watermelon production.