Characterisation and potential new uses of palm tree kale (Brassica oleracea L., ssp. acephala DC, var. sabellica L.)

Palm tree "cabbage" is a local kale type, grown in some areas of inland Tuscany and northern Apennines. Its appreciation has recently grown, opening chances for better exploitation. The adaptability of palm tree kale to intensive growing systems was explored in three field trials carried out near Bologna. The experimental treatments were: 10 sowing rates, (target population: 10-280 plants m(-2)), in fall 1996; 3 sowing rates (60, 120, 240 p m(-2)) and 5 nitrogen levels (0-200 kg ha(-1), at 240 p. m(-2)), in spring 1997. In the fall cycle total fresh biomass reached its maximum (over 30 t ha(-1)) at about 85 days from sowing, without differences in the range 160-280 p. m(-2), whereas it further increased during winter at lower densities. Plant survival was unaffected by competition until 65 days from sowing, when stand reduction started at the higher densities. In spring, biomass constantly increased with time, with response to plant density similar to fall cycle. Leaf-stem ratio, leaf dry matter and fibre content decreased as a function of plant density. 200 and 40 p. m(-2) seemed appropriate densities respectively for mechanical harvesting or top picking for the fresh market. Nitrogen increased total and leaf biomass up to the dose of 150 and 50 kg ha(-1) respectively, causing also a linear decrease of leaf thickness and dry matter content, leaf colour improvement and an increase of leaf fibre: with respect to the unfertilised test. Nitrates increased as a function of nitrogen dose, although remaining at acceptable levels in leaf blades. The results indicate good adaptation of palm tree kale to intensive growing systems.