Influence of Cultural Practices on Triploid Watermelon Yield and Quality

Author

Kaitlyn Lamaster, Southern Illinois University CarbondaleFollow

Date of Award

5-1-2020

Degree Name

Master of Science

Department

Plant and Soil Science

First Advisor

Walters, Alan

Abstract

Triploid watermelon (Citrullus linatus) has gained a significant market share within the United States over the last two decades, and since they require specialized cultural practices compared to seeded types, understanding the influences of these cultural practices on fruit yield and quality is important to maximize production to meet consumer demand. A study was conducted in 2018 and 2019 at the Southern Illinois University Research Center in Carbondale (SIUC HRC) to determine the effect of different cultural practices (e.g., cultivar, pollinizer ratio, water, and nitrogen inputs) on triploid watermelon fruit yield and quality characteristics. Seeded pollinizer ‘Ace Plus’ was inter-planted at 14% and 28.5% pollinizer ratios in two triploid cultivars, Charismatic and Captivation. Neither high nor low water or nitrogen levels evaluated influenced triploid watermelon yields or quality characteristics. Triploid watermelon cultivar influenced fruit size and quality. Both fruit length (P ≤ 0.001) and fruit width (P =0.0055) were influenced by the cultivar used. However, there were no differences for total fruit weight (kg) between the cultivars used. For internal fruit quality, the cultivar used also influenced hollow heart incidence (P = 0.0042). The high cost of triploid watermelon seed and transplants also provide a need to better understand the ratios required to maximize revenue. A field study was conducted in 2018 and 2019 at the SIUC HRC. The objective was to evaluate the influence of different pollinizer ratios on fruit quality, yield, and revenue. ‘Belmont’ triploid watermelon was inter-planted with the diploid pollinizer ‘Ace Plus’ at different diploid to triploid ratios (10%, 20%, 30%, or 40% pollinizer). Our results indicated a linear plateau model between pollinizer ratio and watermelon fruit yield, optimizing at 30% diploid plants in the field. Thus, this study indicated that the highest triploid watermelon yields and revenue were obtained at 30% diploid pollinizer frequency. The identification of an optimum pollinizer ratio for triploid watermelon production can increase grower profits. Low pollinizer ratios can result in low yield and revenue in contrast to higher pollinizer ratios that could result in increased yield production along with decreased input costs. Our results indicated that high fruit number and increased revenue was obtained at an optimal 30% diploid pollinizer inter-planting ratio. This indicates that standard ratios used that are below 30% may not be as economical.