| Studies were conducted to determine the response of Begonia x semperflorens-cultorum Hort. to different levels of light, temperature, and CO{dollar}sb2{dollar}. In the first study, young seedlings of begonia 'Scarletta' were grown under ambient light, 45% shade, or 57% shade in a glass greenhouse from October to February. Shoot dry weight, lateral shoot leaf area, total leaf area, and node number increased quadratically over time due to increased irradiance. Ambient light resulted in faster growth over time than 57% shade. Plants grown under ambient light reached visible bud and anthesis 5 wk before those under 57% shade. Histological examination of shoot apices indicated that floral initiation occurred 2-3 wk later in plants under 57% shade than those under 43% shade or ambient light.; In the second study, plug flats of 'Pizzazz Red', 'Vodka', and 'Viva' were provided 0, 50, 125, and 200 {dollar}mu{dollar}mol m{dollar}sp{lcub}-2{rcub}{dollar} s{dollar}sp{lcub}-1{rcub}{dollar} metal halide supplemental light for 16 hr per day in the greenhouse for 0, 2, 4, 6, and 8 wk. Plug grown begonias reached transplantable dry weight (3 mg) and leaf area (1.4 cm{dollar}sp2{dollar}) after 4 wk supplemental light at 125 {dollar}mu{dollar}mole m{dollar}sp{lcub}-2{rcub}{dollar} s{dollar}sp{lcub}-1{rcub}{dollar} while controls required 6-8 wk. Fewest number of days to visible bud and anthesis, fewest node number, greatest final leaf area and final plant height for all cultivars occurred after 2 wk supplement light at 125 {dollar}mu{dollar}mole m{dollar}sp{lcub}-2{rcub}{dollar} s{dollar}sp{lcub}-1{rcub}{dollar}. Additional supplemental light and/or exposure time did not accelerate flowering or vegetative growth.; In the last study, seedlings of 'Scarletta' were grown in plug flats and placed in environmental control rooms under all combinations of 21 (LT) or 27 (HT) C temperature, 112 (LL), 217 (ML), or 321 (HL) {dollar}mu{dollar}mole m{dollar}sp{lcub}-2{rcub}{dollar} s{dollar}sp{lcub}-1{rcub}{dollar} light, and 445 (LC), 970 (MC), or 1495 (HC) ppm CO{dollar}sb2{dollar} for 2, 4, or 6 wk. Seedling under HT, LL, and MC and HC were transplantable 31 days from sowing and had the largest leaf area. However, HT, HL, and MC produced the greatest seedling dry weight and node number after 4 wk treatment. Seedling chlorophyll content was least and anthocyanin greatest at the highest treatment levels. The number of days to visible bud and anthesis was least for plants that received HT, HL and HC for 4 wk averaging 14 wk from sowing. Final dry weight, leaf area, and flower size were only affected after 4 wk at HT. |
