Use of photoselective plastic films to control growth of three perennial salvias.

Abstract

Photoselective greenhouse films offer a non-chemical alternative to regulate plant growth. Plant response to a photoselective plastic film with a red (R) or far-red (FR) absorbing property was tested using the three perennial salvias: Indigo Spires sage (Salvia x ‘Indigo Spires’) (Salvia longispicata Martius Galeotti x Salvia farinacea Benth.), Wine sage (Salvia splendens ‘Van Houttei’ Sell x roenen Schultes), and Mexican sage (Salvia leucantha Cav.). Films were designated A FR (FR light-absorbing film), A R (R light-absorbing film) and control (clear plastic film). Solar light transmitted through the A FR film reduced plant height by 17-36%, depending on the species. This correlated with a reduction in internode length and stem dry weight. Light transmitted through the A R film did not significantly affect plant height, regardless of species. Leaf area was not significantly affected by the A FR or A R film as compared to the control film, regardless of species. Leaf dry weight of plants grown under A FR was reduced for indigo spires sage and Mexican sage but insignificant for wine sage. Flower development (days to flower and flower number) was not significantly affected by the A FR or A R film as compared to the control film, with the exception that flower number of indigo spires sage was reduced when grown under A FR film. These results indicate that compactness of three perennial sages can be achieved by selective reduction of far-red wavelengths from sunlight.