Optimization of Water and Nutrient Supply during Stock Plant Production and Propagation of Vegetative Cuttings

Adventitious root formation is a complex physiological process affected by anatomical, physiological, and environmental factors and by their interactions. Factors typically manipulated to improve rooting include stock plant cultural practices, storage and shipping conditions, propagation environment, growth regulator applications, and mineral nutrition.;We investigated the potential interaction between storage duration (simulated shipping) and propagation environment on the rooting response of zonal geranium, New Guinea impatiens, and poinsettia. In addition, we investigated whether low cost tent or reemay propagation environments could replace the commonly used mist and fog systems for these three major floriculture species. Of the species tested, zonal geranium cuttings are the most sensitive to storage (simulated shipping) and should be propagated first upon receipt of cuttings. Zonal geranium cuttings stored for 0 d or propagated under mist had the most roots and the highest shoot and root dry weights. New Guinea impatiens may be safely stored in their shipping container overnight if they cannot be propagated on the day of arrival. All tested propagation environments produced similar root counts and chlorophyll fluorescence measurements in New Guinea impatiens cuttings, indicating they can be propagated in any environment. Poinsettia cuttings can be propagated under mist, fog, or tent environments, but should not be propagated under reemay due to reduced survival, root counts, fresh weight, shoot dry weight, and quality.;The effects of water soluble fertilizer application rates and timing during propagation on the adventitious rooting response of zonal geranium and petunia cuttings were investigated. Adventitious root development in zonal geranium cuttings occurred faster and resulted in more fully rooted cuttings with less chlorosis, necrosis, and/or leaf abscission when provided with 50-100 mg˙L-1 N throughout propagation. Petunia cuttings had less chlorosis, necrosis, and/or leaf abscission when provided with 50-100 mg˙L -1 N during the root growth stage. Soluble carbohydrate levels in the leaf, with the exception of sucrose in petunia, accumulated during rooting. Nutrient concentrations, with the exception of boron (B) and zinc (Zn) in zonal geranium cuttings, declined as rooting stage progressed due to dilution. Higher concentrations of magnesium (Mg) during root initiation and early root expression, B during root expression and root growth, and Zn during all stages of adventitious rooting suggest that these nutrients are essential to adventitious rooting in zonal geranium cuttings.;We characterized the adventitious rooting response of zonal geranium cuttings provided a complete nutrient solution or nutrient solutions with either 10% or 0% of B, calcium (Ca), or B & Ca, but including all the other nutrients at the same level as the complete solution. Adventitious rooting was not affected by Fe deficiency, but was affected by B and/or Ca deficiency. Cuttings deficient in B and/or Ca were less likely to survive propagation, rooted slower, and had lower root and shoot dry weights than non-deficient cuttings. Our results indicate that B and Ca are essential to the adventitious rooting of zonal geranium and should be applied to the stock plant at recommended concentrations.