DAY/NIGHT TEMPERATURE ENVIRONMENT AFFECTS CELL ELONGATION BUT NOT DIVISION IN LILIUM-LONGIFLORUM THUNB

Lilium longiflorum Thunb. cv. 'Nellie White' plants were grown in different day/night temperature (DT/NT) environments to determine the anatomical basis for differential responses of stem elongation to DT and NT. Lilium plants were forced in 1986 and 1987 under 25 and 12 different DT/NT environments, respectively, with temperatures ranging from 14 to 30 degrees C. Parenchyma and epidermal cell length and width were measured in stem tissue (1987) and epidermal cell length and width were measured in leaf tissue (1986). Total cell number per internode and vertical cell number per internode were calculated. Stem parenchyma and stem and leaf epidermal cell length increased linearly as the difference (DIF) between DT and NT increased (DIF = DT - NT), i.e. as DT increased relative to NT. DIF had no effect on stem parenchyma width, stem and leaf epidermal cell width, or cell number per internode. Data suggested that stem elongation responses to DIF are elicited primarily through effects on cell elongation and not division.