CARBOHYDRATE FLUCTUATION DURING DEVELOPMENT OF POINSETTIA (Euphorbia pulcherrima Willd) IN TWO LOCALITIES

Abstract

Reducing and total soluble sugars as well as starch were evaluated in leaves from two plant positions (upper and lower), in three poinsettia (Euphorbia pulcherrima Willd) cultivars: ‘Freedom marble’, ‘Supjibi’ and ‘Gutbier V-17 Angelika’, from plants grown at two locations, Cuautla, Morelos and Texcoco, State of México. Artificial flower induction by long nights were applied in Texcoco. Leaf samples were taken at 84, 114, 140 and 155 d after transplant. In Cuautla the average concentration of total soluble sugars was of 27.5 mg g^-1 FW, while in Texcoco was 17.7 mg g^-1 FW. These differences are associated to higher temperature and radiation in Cuautla, Mor. Cultivars ‘Gutbier V-17 Angelika’ and ‘Supjibi’ showed the highest mean concentration of soluble sugars (25.4 mg g^-1) (FW). Upper leaves exceeded lower leaves by 20 to 37 % in total, reducing sugars, and starch. Starch represented the highest proportion of non structural sugars in poinsettia leaves. Thus, the environmental conditions and flower induction by artificial long nights affect carbohydrate behavior in poinsettia leaves.