Growth control of Lisianthus by photoselective plastic films

Plant response to photoselective plastic films with varying spectral transmission properties was tested using lisianthus (Eustoma,grandiflorum) 'Florida Pink', 'Florida Blue', and 'Florida Sky Blue'. Films were designated YXE-10 (far-red light-absorbing film) and SYCE-4 (red light absorbing film). Light transmitted through YXE-10 films reduced plant height compared to control plants by 10% ('Florida Blue'), and stem dry weight by 19% to 40%, but the response varied by cultivar. Internode length was reduced by 10% to 19% when 'Florida Pink' and 'Florida Sky Blue' plants were grown under YXE-10 films. Leaf and root dry weights were not affected by YXE-10 films, with the exception that 'Florida Sky Blue' plants had a lower leaf dry weight than the control plants. Light transmitted through SXE-4 films increased plant height of 'Florida Pink' plants by 15% but not of 'Florida Blue' or 'Florida Sky Blue.' Regardless of cultivar, dry weight of leaf, stem and root tissue was not affected by SXE-4 films as compared to control films. The average number of days to flower and bud number were not affected by YXE-10 or SXE-4 films, regardless of cultivar. The results suggest that selective reduction of far-red wavelengths from sunlight may be an alternative technique for greenhouse production of compact plants, but the magnitude of the response is cultivar specific.