Effect of a red to far red light filtering plastic film on growth of gardenia (Gardenia jasminoides)

Abstract

The aim of this study was to determine the influence of a light filtering plastic film (red to far red ratio modification) on gardenia (Gardenia jasminoides) growth and to investigate the possibility to use this film as a greenhouse cover material for compact gardenia pot plant production in a greenhouse. Experiments were carried out on gardenia cuttings and plants grown under low tunnels covered by a) a light filtering (light modification within the range of 600 to 750 nm) plastic film, b) a plastic film with low radiation transmission or c) a common plastic film. The energy flux entering the low tunnels, within the range of 400 to1100 nm, and the climate parameters, along with plant growth parameters (shoot length, leaf area, number of lateral shoots, number of nodes, leaf and root dry weight) were measured. Cuttings rooted under the light filtering plastic film, receiving light with high R/FR and B/R ratio, were found 68% shorter, and had 21% and 29% lower leaf area and dry weight, respectively, compared to cuttings grown under common plastic film. Developed plants grown under the light filtering plastic film were found 59% shorter, produced no lateral shoots, and had lower leaf area, dry weight and node number compared to plants grown under common covering material. So, light filtering plastic films with high R/FR and B/R ratio, could be promising for greenhouse covering, as an alternative method to chemical growth regulator use, for compact gardenia pot plant production. The effect on lateral branching though, may become a serious problem to the final compact plant formation. For this reason photoselective plastic films with different R/FR and B/R ratios must be tested.