Leaf Tissue Nutrient Sufficiency Ranges of Four Heuchera Cultivars by Chronological Age

Abstract

<jats:p>Coral bells (<jats:italic>Heuchera</jats:italic> sp.) are popular herbaceous perennials grown for their colorful foliage and venation and their aesthetic appeal in mixed containers and landscapes. Commercial coral bell production requires greenhouse or nursery growers to optimize production inputs such as managing mineral nutrition, thereby maximizing plant growth potential and foliage color. The objective of this study was to determine the optimum fertilizer concentrations, identify leaf tissue nutrient sufficiency ranges by chronological age, and to expand leaf tissue nutrient standards of coral bells grown in soilless substrates during container production. Coral bells (<jats:italic>H. hybrida</jats:italic> ‘Black Beauty’, ‘Cherry Cola’, ‘Marmalade’, and ‘Peppermint Spice’), varying in leaf color, were grown under one of six constant liquid fertilizer concentrations [50, 75, 100, 200, 300, or 400 mg·L<jats:sup>−1</jats:sup> nitrogen (N)] with a constant level of water-soluble micronutrient blend in a greenhouse. Fertilizer concentrations for optimal plant growth and development were determined by analyzing plant height, diameter, growth index, and total dry mass, and were found to be 50 to 75 mg·L<jats:sup>−1</jats:sup> N after a nine-week crop cycle. Recently mature leaf tissue samples were collected and analyzed for elemental content of 11 nutrients at 3, 6, and 9 weeks after transplant (WAT) from plants fertilized with 50 to 75 mg·L<jats:sup>−1</jats:sup> N. The black- (‘Black Beauty’) and red- (‘Cherry Cola’) colored-leaved cultivars contained higher total N, phosphorus (P), potassium (K), calcium (Ca), sulfur (S), zinc (Zn), and boron (B) than the orange- (‘Marmalade’) and green- (‘Peppermint Spice’) colored-leaved cultivars. For instance, in mature growth, total N concentration for ‘Black Beauty’ and ‘Cherry Cola’ ranged between 3.45 to 3.63% and 3.92% to 4.18% N, respectively, whereas for ‘Marmalade’ and ‘Peppermint Spice’, ranges were between 2.98% to 3.25% and 2.78% to 3.23% N, respectively. Optimal leaf tissue concentration sufficiency ranges determined in this scientifically based study were narrower and often times higher than previously reported survey values for coral bells.</jats:p>

Establishment of Leaf Tissue Nutrient Sufficiency Ranges of Two Perovskia Selections by Chronological Age

“…Sufficiency ranges for both Perovskia selections were used to determine recommended leaf tissue concentrations of 11 elements by chronological age. Similar to the results found by Owen (2019aOwen ( , 2019b, lower and upper limits of recommended leaf tissue concentration ranges were defined by analyzing data for each Perovskia selection grown at 100 to 200 mg • L -1 N over a 6-week crop cycle. Although only one record (Biernbaum and Morrison, 2000) (Table 2) of recommended leaf tissue values for common Russian sage grown in soilless substrate exists, previous work did not establish leaf tissue concentration limits.…”

“…Increasing leaf tissue concentrations by chronological age of all macronutrients, specifically, P and K, may indicate that plants were supplied with more nutrients than needed for their metabolic requirements (luxury consumption); therefore, the recommendations may be lower than observed in the current study for the two Perovskia selections. Increased Ca concentrations over the 6-week crop cycle may be attributed to increased amounts of NO 3 --N (13.1%) compared to NH 4 + -N (1.9%) provided by the fertilizer (Owen, 2019b), because NO 3 usually increases Ca uptake (Bryson and Mills, 2014). Increasing tissue Mg concentrations may likely be attributed to the consistent volume of MgSO 4 applied, as suggested by Owen (2019a;2019b).…”

“…is a popular ornamental herbaceous perennial grown for its fragrant blue flowers, drought and salt tolerance, deer resistance, and use as a pollinator plant (personal observation); its reported wholesale value was $3.8 million in 2014 (U.S. Department of Agriculture, 2015). To produce high-quality containerized plants, greenhouse growers must optimize production inputs such as fertilization (Owen, 2019a(Owen, , 2019b. To date, mineral nu-trition recommendations for commercially grown Perovskia do not exist.…”

“…Generally, growers of herbaceous perennials will provide crops with water-soluble fertilizer applications of 50 to 250 mg • L -1 nitrogen (N) on a continual basis or 150 to 700 mg • L -1 N applied weekly (Pilon, 2006). The philosophy of this approach involves monitoring the inputs to the crop and, as long as the substrate inputs are within the recommended range, e.g., substrate pH and electrical conductivity (EC), it is assumed that the fertility requirements of the crop are being met (Krug et al, 2010;Owen, 2019b). However, these fertility recommendations vary greatly, are not species-specific, and may result in deficient or excessive fertility levels provided to crops.…”

“…Leaf tissue nutrient sufficiency ranges by chronological age for herbaceous perennials have only been reported for perennial hibiscus (Hibiscus hybrid L. 'Mocha Moon' and 'Starry Starry Night';Owen, 2019a) and coral bells (Heuchera hybrida L. 'Black Beauty', 'Cherry Cola', 'Marmalade', and 'Peppermint Spice';Owen, 2019b). For annual bedding plants, leaf tissue nutrient sufficiency ranges by chronological age have been reported for coleus [Plectranthus scutellarioides (L.) Codd 'Broad Street', 'Stained Glass Eruption', and 'Wall Street';Henry et al, 2019], gerbera (Gerbera jamesonii Bolus ex Hook.…”