Phenotypic plasticity and nutritional quality of three kale cultivars (Brassica oleracea L. var. acephala) under field, greenhouse, and growth chamber environments

Comparative analysis of the physiological and biochemical characteristics of three kale cultivars ('Toscano', 'Redbor', and 'Winterbor') in different agricultural systems was performed. High biomass yield was observed in the plants grown in the field and greenhouse systems likely due to the higher light intensity (sunlight) and lower planting density during growth. The highest relative growth rate was observed in the field for 'Redbor' (104 mg g-1 d-1) and 'Winterbor' kale (115 mg g-1 d-1), while the highest growth rate for 'Toscano' kale was found in the greenhouse system (109 mg g-1 d-1). For all three cultivars, the smallest growth rate (72 - 78 mg g-1 d-1) and leaves with the highest specific-leaf area (295 - 378 cm2 g-1) were observed in the growth chamber environment. However, the highest concentration of phytochemicals (lutein, violaxanthin, chlorophyll a, and chlorophyll b) was detected in kale leaves from the growth chamber. The macular pigment, zeaxanthin, was detected in leaf samples harvested from the field and greenhouse grown kale primarily during high light conditions (PPFD > 1000 mu mol m-2 s-1). Based on interaction study, cultivar type (genotype), growth stage at harvest, and farming system were identified as primary factors that determine nutritional quality in kale.