In the era of rapid climate change, urban farmers are seeking heat-tolerant crops to meet needs of consumers. Tropical crops, such as Hibiscus sabdariffa L., may thrive despite increasing temperatures. Most studies on H. sabdariffa production have been conducted in tropical areas and, to our knowledge, none compared genotypes, determined nutrient profiles, or determined urban production suitability. Therefore, we grew seven genotypes of H. sabdariffa in three production systems (i.e., green roof, field row, and high tunnel) in and near Washington, DC primarily to determine differences in: 1) leaf and calyx yield between genotypes; 2) nutritional content of leaves between genotypes; and 3) susceptibility of genotypes to insect pests. Comparison between production systems was a secondary goal. In year 1 we grew five genotypes of Hibiscus sabdariffa from the USDA germplasm repository (PIs: 256041, 275414, 286316, 267778, 273388) on a green roof and in field plantings. In year 2 we grew a commercial Thai red variety and a green variety, which had been cultivated through a mass selection breeding program in the DC area for over a decade, in addition to the USDA germplasm genotypes. We also added a high tunnel system to extend the growing season.
Results/Conclusions
Two distinct groups emerged when comparing leaf yield on the roof in year 1: PI 273388 outperformed PIs 256041, 275414, and 286316. PI 273388 along with PI 275414 were the highest performers in the field in year 1. In year 2, PI 273388 and the green variety produced the highest leaf yield on the green roof. These two genotypes also produced the highest yields in the field along with PI 275414 and Thai red. In the high tunnel, PIs 273388 and 275414, Thai red, and the green variety were the top performers. The green variety also had the fewest Japanese beetles in the field, which is the main pest of this crop in the mid-Atlantic. Phenolic profiles of different genotypes were marginally different in year 1. The concentration of phenolics and sugars were comparatively higher in leaves grown on the green roof as compared to the farm in year 1. Nutrient analysis of leaves and calyces is ongoing. In conclusion, our results so far indicate that the green variety, shows the most adaptability to a range of growing systems and environmental conditions.