PLANT HEIGHT FORMATION IN DIFFERENT CULTIVARS OF KALANCHOE

The control of plant height is of great importance in pot plant production. In the present work, data from greenhouse experiments and from a grower were used to evaluate plant height in several kalanchoe cultivars and to study the seasonal pattern in plant height. Plant height could be separated into a vegetative stem length, with all internodes of a similar length, and a generative stem length. The generative stem length consisted of one or two internodes, significantly longer than the vegetative internodes, and the peduncle of the top inflorescence. For 20 cultivars, varying in plant height between 10 and 32 cm, it was observed that plant height correlated with average vegetative internode length (r²=0.86) and not with internode number (r²=0.15). The ratio between vegetative and generative length was found to be cultivar specific and it varied between 0.4 and 3.0 for the studied cultivars. Stem elongation rate was reduced for plantings in the second half of the year and it showed a positive correlation with average temperature and average incident PAR during the short-day period. It seems likely that the light effect is mainly caused by the higher temperatures co-incident with the higher light integrals. The importance of these findings for modelling plant height in kalanchoe is discussed.