S06 - Session P2 - Comparative performance of hydroponically grown broccoli and cauliflower cultivars in different growth seasons

Authors: Helena Hartley, Martin Maboko, Retha Slabbert *

A study was conducted to evaluate the growth, yield, quality and nutrient content of four broccoli cultivars ( Brassica oleracea L. italica; cultivars Diamond, Majestic, Parthanon & Star 2204) and four cauliflower cultivars ( Brassica oleracea L. botrytis; cultivars Crenique, Sierra Madre, Telergy & Star 4418) over four seasons (autumn, winter, spring and summer) in an NFT hydroponic system. Growth season had a pronounced effect on the growth, yield, quality, nutrient content and yield parameters of the broccoli and cauliflower cultivars tested. Leaf number, leaf area and plant height were higher during the seasons with a higher ambient temperature for both crops. General plant appearance and general plant colour was not affected by season. Both fresh and dry weight of broccoli was higher during spring (cooler season) while curd fresh and dry weight for cauliflower was higher during the summer (warmer season). Broccoli head rejections were mainly due to deformed heads and open florets during summer and spring, while cauliflower curd rejections were mainly due to riceyness during winter and curd discolouration during spring, and was associated with cultivar choice and season. The total number of days from transplant to maturity was in general the shortest during summer for broccoli, although the marketable yield was also the lowest in the warmer season, compared to autumn and spring where maturity took longer but the marketable yield was the highest. For the cauliflower cultivars tested, the days to maturity was shorter during summer, and the highest marketable yield was also obtained during the warmer season. The highest harvested yields with shortest days to maturity were obtained in autumn and spring for broccoli cultivar Star 2204 (87.0 to 100%) with 78 to 87 days to maturity and a head weight of 292.7 to 514.9 g. The highest harvested yields with shortest days to maturity were obtained in summer for cauliflower cultivar Crenique (95.0%) with 66 days to maturity and a curd weight of 1067.7 g. Mineral content (Ca, Mg, P, Fe, Zn, B & Cu) varied over the seasons and between cultivars. The Ca an Mg content of broccoli was the highest in cultivar Diamond and the lowest in cultivar Parthenon of all cultivars tested over all four seasons, while cultivar Parthenon had the highest B content. Ca content was the highest for cauliflower cultivar Crenique.