Abstract
The effect of simulated shipping and other cutting quality factors on rooting and cutting quality of coleus, Solenostemon scuttellarioides (L.) Codd. (also known as Coleus×hybridus Voss) 'Solar storm' was investigated. Coleus cuttings were taken from stock plants and either directly planted in plug trays and placed under an intermittent mist propagation environment or placed under simulated shipping conditions prior to propagation. Three series of experiments were done. The first series was to determine the influence of leaf area on rooting. Thick stem cuttings were selected and all the leaves were retained, half of the leaves removed or all the leaves removed. The second series determined the effects of cutting thickness on rooting. Cuttings of equal length (~5 cm) were grouped in two size classes according to stem diameter: thick stem cuttings and thin stem cuttings. The third series involved placing the cuttings under simulated shipping conditions in the dark at 22C for up to seven days. Chlorophyll content was estimated using a SPAD meter both prior to and post shipping. The results show the coleus root system from cuttings with thick stems had better root systems than thin stems. The amount of foliage retained on cuttings strongly influenced rooting quality. The simulated shipping showed that the control (0 days in shipping) rooted well and as shipping days increased, cutting quality deteriorated and rooting response declined. This result suggests that cuttings cannot survive under shipping conditions for long periods and must be taken out of the shipping environment before 6 days to maintain foliage and produce adventitious roots. The SPAD readings indicate a reduction in chlorophyll as the leaf degrades, and results of shipping are similar to the results when leaves were mechanically removed from cuttings. The results show that high quality cuttings can be shipped for short time periods without serious decrease in quality and rooting, but the breaking point is five days for high quality rooted cuttings.
