Deficiência de macronutrientes em helicônia "Golden Torch"

Abstract

In order to describe Heliconia psittacorum x Heliconia spathocircinata ‘Golden Torch’ nutritional deficiency symptoms, evaluate macronutrients omission effects on growth, first flower stem characteristics and longevity, greenhouse experiments were conducted under the lacking element technique. The lacking macronutrients treatment reduced growth, shoot tillering and dry weight production compared to the complete nutrient solution treatment. Nutrient symptons occurred as follows: N,K, P, Mg and S. Deficiency symptoms were general chlorosis at – N treatment; slight chlorosis at – P and – S; dark green leaves and necrosis at – K; border chlorosis and necrosis at – Mg. The lack of Ca did not show any visual symptoms.The omission of each macronutrient in the nutritive solution reduced its respective concentration in the plant. Among the evaluated leaves, the concentration tended to a greater reduction in the third leaf. Based on the third leaf macronutrients contents on g kg-1 at the first emitted shoot, the following values were found for complete solution treatment and lacking nutrients treatments, respectively: N =16,28 e 7.87; P = 1,49 e 0, 68; K = 32,68 e 3,26; Ca = 8,76 e 3,38; Mg = 1,75 e 0.70; S = 6,00 e 1,82, at 90 days e N = 24,40 e 5,32; P = 1,32 e 0,46; K = 12,88 e 3,50; Ca = 4,58 e 0,97; Mg = 0,98 e 0,62; S = 4,44 e 1,00, at blooming period. The Heliconia psittacorum x H. spathocircinata ‘Golden Torch’ inflorescence produced under N omission showed a pale orange color and floral stem deformation. N, P and K omission affected stem length, stem diameter, inflorescence length and postharvest longevity, which are considered to be important market characteristics. Macronutrients deficiency reduced floral stem production. Greater postharvest longevity is to be found at higher floral stem dry matter. Carbohydrate ratio in underground parts has positive correlation with floral stem dry matter.