Abstract
Nutrient uptake during adventitious root formation is not clearly understood, resulting in variable fertilization strategies in propagation and increased potential for nutrient deficiency or nutrient runoff. The objective was to quantify rooting response to fertility treatments and tissue nutrient concentration changes in response to basal or apical nutrient supply during three rooting phases in propagation of Petunia ×hybrida ‘Supertunia Royal Velvet’ and ‘Supertunia Priscilla’ stem tip cuttings. One of two treatments [a complete fertilizer solution (in mg·L−1) 56 NO3-N, 19 NH4-N, 13 phosphorus, 88 potassium, 39 calcium, 28 magnesium, 20 sulfur, 11 sodium, 1.1 iron, 0.5 manganese, 0.5 zinc, 0.25 copper, 0.29 boron, 0.1 molybdenum, and 0.01 aluminum] or clear tap water was applied to the cuttings. Tissue N–P–K concentrations declined as plant development increased from Stage 0 to 3 regardless of fertilizer treatment or location applied. Foliar application of N–P–K during propagation maintained tissue nutrient concentration at higher levels before Stage 2 (initial root emergence) compared with plants that received clear water only; however, overall, a decline in concentration was measured from Stage 1 to Stage 3. Measurable N–P–K uptake occurred during root development from the foliar and basal portions of the cuttings. Basal fertilizer applications resulted in increased root length and root number compared with plants treated with clear water. These results emphasize that nutrient uptake occurs from both the stem and foliar portion of Petunia cuttings, and nutrient availability at the stem base at root emergence improves root development.
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