Date of Award
2025
Degree Type
Thesis
Degree Name
Master of Science in Biological and Environmental Sciences (MSBES)
Department
Biological Sciences
First Advisor
Rebecca Brown
Abstract
In the United States, broccoli is a popular vegetable, important for its nutrition and economic contributions alike. However, its future production is at risk as broccoli prefers cooler climates, with an optimal temperature range of 15 - 23°C (59 - 73°F) for growth, especially in the weeks leading up to harvest. Temperatures above this threshold lead to failure to develop, damage, and unmarketability. There has also been an emphasis on bringing broccoli production back to the East coast from California, as climate events threatened Californian agriculture and local food has become popular, necessitating outside of season broccoli production during times like the summer to meet demand. We conducted variety trials of 12 recently developed heat-tolerant broccoli cultivars using a randomized block design and staggered planting dates throughout the summer of 2024. We aim to determine a subset of heat-tolerant broccoli varieties that perform the best, using standard measures of quality and yield, in Rhode Island’s microclimate. A subset of varieties (SVBL-2159 and Tlaloc) fare worse than others (EXP-3622, Eastern Crown, Eastern Magic, and Green Magic) in a warm environment.
A comparative multi-location study was also conducted during summer 2024, with locations in Kingston, RI from succession 1 from the previous experiment; Riverhead, NY; and Melrose, NY to account for diversity of climatic conditions and lack of summer broccoli trials throughout the Northeast. A subset of eight varieties was used for analysis, with slight differences in production methods and schedules (most notably, transplant in Kingston on June 5th, in Riverhead on May 29th, and in Melrose on July 5th). All production systems used a randomized complete block design. As expected, varietal performance varied by location, as genotype x environmental effects proved significant. Percent marketable, survival, and heat tolerance tended to be higher at more inland sites, suggesting that the varieties trialed are less well-suited to extremely coastal locations. Generally, yields and head sizes in Melrose were lower than in the other two locations, but had high rates of survival and survival, while Riverhead showed the opposite pattern, suggesting a potential tradeoff between yield and quality depending on environment. Castle Dome, Eastern Magic, and to a lesser extent, Imperial and Millennium, were generally poor performers in these areas and are not recommended for summer production in the Northeast. Eastern Crown and Emerald Crown, with consistent quality and earliness, are recommended for Northeastern summer production based on this trial. EXP-3622 also performed reliably well, though it took longer to mature. The results emphasize the importance of multi-location trials to inform varietal recommendations for summer broccoli production in the Northeast. Recommendations from both trials will help ensure the future of the crop to meet nutritional needs and demand of the population, as well as economic needs for farmers by preventing yield loss, especially for small-scale, diversified farms that grow and distribute on a local level in Southern New England.
Recommended Citation
Pederson, Calla, "EVALUATING YIELD AND QUALITY OF HEAT-TOLERANT BROCCOLI VARIETIES FOR RHODE ISLAND FARMERS" (2025). Open Access Master's Theses. Paper 2663.
https://digitalcommons.uri.edu/theses/2663