Manipulation of light environment to produce high-quality poinsettia plants

Abstract

The phytochromes, a family of photoreceptors that maximally absorb red (R) far-red (FR) light, play an important role in defining the architecture of the plant and its value in the market. In this work, we evaluated the manipulation of light as an alternative to the use of plant growth regulators (PGRs) to produce plants (Euphorbia pulcherrima Willd. ex Klotzsch) without affecting commercial parameters. 'Freedom Red' poinsettia plants were cultivated in two light characterized by different R/FR ratios in combination with or without one of PGR. We used a photoselective film that significantly reduced the FR of the light and a transparent film to obtain high and low R/FR ratios (5.7 and .1, respectively). Plants cultivated under a high R/FR ratio were shorter and more than those grown under transparent film. Other quality characters like bract leaf area, dry weight, stem diameter, number of lateral branches, and plant width did differ significantly between light treatments. Flowering time was slightly del yed in grown under a high R/FR ratio compared with those cultivated under the control . Additive effects were detected between light quality and PGR factors that light quality manipulation is an alternative strategy to reduce or to the use of PGRs in commercial production systems that usually require several PGR applications.