Growth of Six Begonia Species Under Shading

The Ornamental Plant Germplasm Center (OPGC) conserves begonia species. Limited cultural information is available concerning the effect of light intensity on the growth of begonia species other than cultivated hybrids in green- houses. The objective of this study was to evaluate the response of begonia species to different shade levels and to identify light intensities that favor the production and maintenance of quality begonia plants in greenhouses during summer. Plants of six begonia species, (Begonia albopicta, B. cucullata var. cucullata, B. echinosepala var. elongatifolia, B. holtonis, B. foliosa var. miniata, and B. 'Fuchsifoliosa' (B. fuchsioides x B. foliosa)), were grown in a greenhouse in Columbus, OH (lat. 40 N, long. 82.53 W) for 12 weeks (starting 23 July) either in full light (1000 - 1800 μmol·m -2 ·s -1 ) or shade-cloth tents providing three levels of shade (41, 62, and 76% of full sunlight in the greenhouse). Each plant was evaluated for the number of inflorescences, leaf greenness (SPAD readings), shoot length, leaf area, and shoot dry weight. Visual observa- tions of plant quality (chlorosis, necrosis, sunburn, deformed leaves, and plant mortality) were also recorded. Shade per- centage for optimal growth and quality of B. albopicta, B. echinosepala var. elongatifolia, B. holtonis, B. foliosa var. miniata, and B. 'Fuchsifoliosa' plants was 62% and 76 % for B. cucullata var. cucullata plants.