ISHS Acta Horticulturae 631: XXVI International Horticultural Congress: Issues and Advances in Transplant Production and Stand Establishment Research
EXCLUSION OF FAR RED LIGHT BY PHOTOSELECTIVE GREENHOUSE FILMS REDUCES HEIGHT OF VEGETABLE SEEDLINGS |
| Authors: | N.C. Rajapakse, S. Li |
| Keywords: | plant growth regulation, photomorphogenesis, greenhouse covers |
| Abstract:
The effectiveness of two types of far red (FR) light absorbing greenhouse films in reducing stem elongation of cucumber, tomato, and bell pepper seedlings was investigated. A clear film (control) and two FR light intercepting films (Afr1 and Afr10) with R:FR ratios of 1.04, 1.99, and 1.66, respectively, were used as the covering materials of experimental chambers. Photosynthetic photon flux (PPF) was adjusted to be the same in all chambers with cheesecloth. Both FR light absorbing films were effective in reducing stem elongation and producing compact of cucumber, bell pepper, and tomato seedlings. Although the R/FR ratio was lower, Afr10 film was more effective than Afr1 film in reducing stem elongation rate suggesting that R/FR ratio is not a good indicator for gauging the effectiveness of films. Cucumber seedlings were more responsive to filtered light than the tomato or pepper seedlings. Number of leaves was not affected by the light transmitted through photoselective filters, indicating that the height reduction was mainly caused by the reduction in internode length. Photoselective films reduced total shoot dry matter but the reduction was mainly due to the smaller plants because specific leaf or stem dry weights were not affected. Significant reduction in stem elongation could be achieved by the exclusion FR light at the end of the day by covering west and south facing walls of the chambers or by exposing plants to photoselective films at the end of the day. However, this was not as effective as the continuous exposure. Using photoselective films as an end of day (EOD) curtain allows growers to make use of high light during the day and eliminate elongation stimulating FR light in the evening. Further research should evaluate the effectiveness of photoselective films as an EOD curtain in other crops. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
