Influência da distribuição da solução nutritiva na produção e no teor em fenóis totais e poder antioxidante em Spinacia oleracea cultivada em coco.

Abstract

Leafy vegetable production in substrate has been increasing in Portugal. The advantage of using cocopeat is that it is a biodegradable and renewable resource that allows reaching high yields in different vegetable crops. The objective of this study was to evaluate the influence of nutrient solution distribution on the yield, phenols content and antioxidant power (FRAP) in spinach grown in cocopeat. The experiment was carried out with two treatments, four and eight water emission points per Styrofoam box, in a randomized block with five replicates boxes by treatment. Soil blocked spinach seedlings (five per soil block, 160 plants m-2) were transplanted at 18 days after emergence into Styrofoam boxes filled with cocopeat and placed in a greenhouse. The plants were irrigated daily with a nutrient solution. The yield (fresh weight, FW) increased with the number of water emission points, reaching 3.55 kg m-2. The total phenol content and FRAP of leaf-blade decreased with the water emission points 23% and 25%, respectively. The phenol content of the petiole (15 mg eq. gallic ac/100 g FW) was much lower than that of the leaf-blade and was unaffected by the treatment. The antioxidant power of leaf- blade was positively correlated with total phenol content of the leaf-blade (r = 0.79, p <0.01).