Articles
EFFECTS OF HIGH TEMPERATURES AND DIF ON POTTED FOLIAGE PLANTS
The plant species were Chrysalidocarpus lutescens, Codiaeum variegatum ‘Norma’, Dracaena deremensis, Dracaena fragrans, Epipremnum pinnatum, Ficus benjamina ‘Cleo’, Ficus elastica ‘Robusta’, Ficus pumila ‘Sonny’ and Radermachera sinica.
Internode length was reduced with increasing (neutral DIF) temperature from 21/21 to 33/33°C in Ficus benjamina and Epipremnum, but was increased in Ficus elastica. In Codiaeum internode length increased from 21/21°C to 25/25°C and decreased markedly at 33/33°C where plants were clorotic and dropped leaves.
The number of lateral shoots was unaffected in Dracaena, Ficus benjamina, but greatly increased with increasing temperature in Ficus pumila and Radermachera.
The number of leaves increased with increasing temperature in Dracaena fragrans, Ficus pumila and Radermachera. In Chrysalidocarpus 25°C produced the most leaves.
Leaf length and leaf width generally decreased with increasing temperature, however leaf length had optimum at 25°C in Codiaeum and at 29°C in Ficus elastica. Production time was markedly decreased with increasing temperature from 21/21 to 29/29 in Chrysalidocarpus, Dracaena fragrans, Codiaeum and Epipremnum. In Ficus elastica and Ficus benjamina production time decreased up to 33/33°C. Conversely production time increased with increasing temperature above 21/21°C day/night in Ficus pumila ‘Sonny’. Minus 6 DIF treatments 23/29 or 27/33°C day/night compared to neutral DIF treatments with same average temperatures had little influence on internode length, number of lateral shoots, number of leaves, leaf length and leaf width.
Only Codiaeum responded with significant shorter internodes or shoot length in the magnitude of 10% compared to neutral DIF with the same average temperature.
Plant production time was either not influenced or prolonged depending on plant species.