Effects of Fertilizer Application and Photosynthetic Photon Flux Density on Chrysanthemum and Begonia Cuttings Acclimated Indoors

The objective of this study was to evaluate the effect of fertilizer application and photosynthetic photon flux density (PPFD) on shoot and root growth of chrysanthemum ( Chrysanthemum indicum ) and begonia ( Begonia × hiemalis ) cuttings. During an acclimation phase indoors, unrooted cuttings were treated with a complete fertilizer solution (15N–2.2P–12.5K with micronutrients) that provided 100 mg·L −1 nitrogen or with tap water. Cuttings were placed under PPFDs of 70 or 140 µmol·m −2 ·s −1 provided by broadband white light-emitting diode fixtures. A finishing phase in a greenhouse was conducted to evaluate carryover treatment effects. Fertilizer application had minimal effects on cuttings during both the acclimation and finishing phases. However, the higher PPFD increased shoot dry weight (DW) in both species and produced shorter chrysanthemum cuttings with almost double the root DW and higher chlorophyll concentration than those under the lower PPFD. During the finishing phase, chrysanthemum cuttings that had been acclimated under the higher PPFD produced 9% and 14% more shoot and root DW, respectively, than those under the lower PPFD, but no treatment differences were measured for begonia. Overall, our results suggest that when there is a fertilizer starter charge present in the substrate, additional fertilizer application during indoor acclimation will not affect shoot and root growth of chrysanthemum and begonia cuttings under conditions similar to those used in our study. Furthermore, cuttings of high-light-requiring species such as chrysanthemum are more likely to benefit from higher PPFD during indoor acclimation than those that require less light such as begonia.