Poinsettia Irrigation Based on Evaporative Demand and Plant Growth Characteristics

Abstract

Abstract An easy method to estimate water requirements for poinsettia (Euphorbia pulcherrima Willd. ex Kl.) production with practical applications to commercial operations was developed to promote water conservation. A water-requirement prediction equation (P ≥ 0.01, R2 = 0.78) that used pan evaporation along with plant-canopy height and width as input variables was generated. Equation verification was carried out by comparing plant quality of crops irrigated according to the generated water-requirement prediction equation to crops irrigated “on-demand” or with capillary-mat irrigation. Plants irrigated with the prediction equation were smaller than plants grown with capillary mat, but plant quality ratings for ‘Annette Hegg Diva’ and ‘Dark Red Annette Hegg’ were not significantly different. ‘Gutbier V-10 Amy’ plants grown with irrigation on-demand were of higher quality than plants grown using either the capillary mat or the prediction equation. Applied water was significantly lower for plants irrigated with the prediction equation than would normally be applied in a commercial operation using a conservative fixed daily irrigation rate.