EUPHORBIA CYPARISSIAS AS A LOW TEMPERATURE FOLIAGE PLANT

The more important cultural techniques for the production of E. cyparissias as a low temperature indoor ornamental foliage plant were investigated. During the rooting phase a 30°C basal temperature resulted in an increased rate of rooting compared with 24° and 18°C, but the beneficial effects diminished with time. The use of rooting hormone (0.2% IBA) significantly improved the rate of rooting and increased root number and the effects were still evident at the end of the experiment. Supplementary lighting during rooting had a slight beneficial effect, but would not be commercially feasible.

Plants grew best in low to medium pH range of 4.5–5.5 in peat compost and in 5.0–6.0 in loam-based compost. Growth and development was far superior in the peat compost.

In a comparison of a range of light regimes (8 and 16 hour photoperiods in combination with 6,500 and 13,000 lux), best visual appearance and highest plant dry weight were produced in the highest integral (208 klux-hrs). At the intermediate light integral of 104 klux-hrs growth was more satisfactory at the 16-hour photoperiod. Dry matter production at the highest light integral was 10 times greater than at the lowest light integral (52 klux-hrs).

In a comparison of three growth retardants, applied at a range of spray and drench concentrations, Amcymidol was the most effective at a drench concentration of 5–10 mgl^-1. Higher spray levels of Chlormequat and Daminozide produced phytotoxic foliar symptoms and neither significantly reduced plant size.