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  • Author or Editor: Kate Cassity-Duffey x
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Industrial hemp (Cannabis sativa) cultivars used for flower, fiber, or seed production are usually considered short-day plants and flower in response to photoperiod. However, some cultivars of hemp are day-neutral, where flower induction may be independent of daylength. Day-neutral cultivars of hemp were planted before recommended dates and studied in field experiments conducted in Watkinsville, GA, in Spring 2020 and 2021. Day-neutral cultivars (Pipeline and Maverick) and photoperiod-sensitive cultivars (Von and Whitehouse Cherry) were planted on 9 and 25 Apr and 11 and 28 May to determine the impact of planting date on hemp flower yield and quality. Planting date did not impact yield of the photoperiod-sensitive cultivars, but yields of day-neutral cultivars decreased as planting date progressed. Average yields of photoperiod-sensitive plants were greater than the day-neutral cultivars in both study years. Cannabinoid concentrations in flowers were affected by cultivar and study year but were not impacted by planting date. Cannabidiol was the most prevalent cannabinoid in flower tissue with concentrations ranging from 6.5% to 10.5%. Flower biomass yields suggest that the spring hemp planting season may be extended using day-neutral cultivars in the southeastern United States.

Open Access

Georgia is a leading fresh market cabbage (Brassica oleracea var. capitata) producer. Current recommendations for bare-ground cabbage grown in the Coastal Plain of Georgia indicate 175 to 225 lb/acre nitrogen (N). Approximately one-third of N fertilizer is recommended at planting, with two or three additional side-dress applications during the season. Growers have begun banding liquid fertilizer between four and six times during the season to reduce N leaching and enhance productivity. To determine the validity of current recommendations as well as the efficacy of applying periodic liquid fertilizer throughout the growing season, field experiments were conducted in Tifton, GA in Fall 2016 and 2017 with the cabbage cultivar Cheers. Fertilizer N rates were 175, 200, 225, and 250 lb/acre N applied using equivalent preplant fertilizer (50 lb/acre N) with two posttransplant applications of a granular fertilizer (27–0P–0K–5Ca) or six applications of a liquid fertilizer (9N–0P–0K–11Ca). A factorial, randomized, complete block design was used. There were no interactions among fertilizer program, N rate, or year for cabbage yield or nutrient concentrations. Total yield was unaffected by the N rate. However, plants fertilized with the lowest N rate (175 lb/acre N) had the lowest yields from the first two harvests compared with the other N rates. Nutrient concentrations were affected by year, with 2017 having greater concentrations of most macronutrients compared with 2016. In conclusion, the application of 175 lb/acre N led to a potential delay in harvest, but all other N rates were equal. The application method did not impact yield or earliness, suggesting that current recommendations for fertilizer applications after planting cabbage in Georgia are adequate.

Open Access