MACRONUTRIENT EXTRACTION AND GROWTH OF MEXICAN NATIVE SUN POINSETTIA VARIETIES

Abstract

Sun poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) is a Mexican native genetic resource of great economic importance in the ornamental market. Since published information about poinsettia nutrition is limited, in this study the main objective is to measure the total demand of plant macronutrients and the nutrimental absorption dynamics, for determining the main macro-nutriments in sun poinsettia, and for assisting in generate technological guides, to reduce production costs and reduce pollution of natural resources. Two sun poinsettia varieties, Valenciana and Rehilete, were grown under greenhouse conditions with an open hydroponic system with red volcanic rock as substrate. The Steiner nutrient universal solution under -0.072 MPa osmotic potentials was used. The total nutrient extraction (mg/plant) obtained at the end of cycle (240 d) was higher in var. Rehilete than in var. Valenciana: N 1269 vs. 947; P 137 vs. 115; K 433 vs. 390; Ca 234 vs. 192; y Mg 153 vs.143, respectively. The sequence of nutrient extraction in both varieties was: N > K > Ca > Mg > P. The maximum rates of N and K absorption in Valenciana was during the vegetative stage, while for P, Ca and Mg was at the inductive stage, with values of N, P, K, Ca and Mg of 12.1, 1.3, 4.4, 1.7 and 1.4 mg/plant per day, respectively. In Rehilete, the maximum rates of all nutrient absorption were in the vegetative stage, with values of N, P, K, Ca and Mg of 13.6, 2.1, 6.0, 3.0, and 2.0 mg/plant per day, respectively.