Growth and plant morphology of Cucumis sativus and fuchsia x hybrid are influenced by light quality during the photoperiod and by diurnal temperature alternations

摘要

The impact of different light qualities during the photoperiod (day) on plant growth and morphology by selective screening of daylight in combination with alternating day (DT) and night temperature (NT) was investigated in cucumber (Cucumis sativus) and Fuchsia x hybrida cv. Beacon. In addition, the effect of different lamp types on Fuchsia morphology was studied in growth cabinets. Modification of the daylight by screening light through light quality selective plastic films from Mitsui Chemicals, Ltd., Japan, which created a high red (R)/far-red (FR) ratio (1.6) (film type YXE-10), resulted in 45-50% shorter stem length of cucumber compared to a control film (R/FR ratio = 1.1). Plants grown under a plastic film with a R/FR ratio of 0.75 (SXE-4), showed an enhancement in length of 21 and 41% under negative (DTNT) treatments, respectively. The response to a change in R/FR ratio was almost similar under low and high light intensity. In contrast to cucumber, the effect of a high R/FR ratio of the daylight had a rather small effect in Fuchsia. However, a lower DT than NT (negative DIF) reduced plant height significantly in both species. Experiments with Fuchsia grown at a PPF of 200 mumol m(-2) s(-1) in growth cabinets showed that the plant height was reduced about 20% when the R/FR ratio in the light spectrum was changed from 1.1 to about 8, while a combination of high R/FR ratio and additional blue light reduced plant height about 30%. However, this light combination resulted in a delay of flowering. A high R/FR ratio resulted in less accumulation of dry matter in the plant and more dry matter distribution to the leaves than to the stem compared to plants grown under a low R/FR ratio.