INFLUENCE OF SPECTRAL FILTERS ON GROWTH AND POSTHARVEST QUALITY OF POTTED MINIATURE ROSES

The role of light quality on growth and postharvest characteristics of potted miniature roses (Rosa X hybrida cultivar 'Meijikatar') was eva luated using 6% CuSO4 and water (control) as spectral filters. The CuS O4 spectral filters reduced R and FR wavelengths and increased the R:F R, B:FR and B:R ratios (R=600-700 nm; FR=700-800 nm; B=400-500 nm) and 0 of transmitted light compared with control filter. Light transmitte d through the CuSO4 filter significantly reduced plant height and inte rnode length and increased the number of lateral shoots compared with control plants. However, the degree of response varied with growing se ason. CuSO4 filters slightly accelerated flowering in early spring-gro wn plants but slightly delayed flowering in late spring and summer. To tal number of flowers was not affected by spectral filter but plants g rown under control filter had larger flowers than those grown under th e CuSO4 filter. Light transmitted through CuSO4 filter reduced leaf su crose and starch concentration by 40% and 65%, respectively. Leaf gluc ose and fructose concentrations were not affected by light quality. Po stharvest quality of plants grown under CuSO4 and control filters was reduced and leaf yellowing increased as the shipping temperature incre ased. Light quality in the growing environment did not significantly r educe the overall appearance of plants shipped at 4 degrees C or 15 de grees C. However, plants grown under CuSO4 filter had slightly higher percentage of yellow leaves than the corresponding control plants afte r shipping at any temperature. Alteration of light quality in the gree nhouse can be used to control height of rose plants but extended shipp ing at high temperatures could result in leaf yellowing possibly becau se of reduced carbohydrate status.