Effects of Supplemental Light Quality and Foliar Application with Calcium on Photosynthetic Parameters and Flower Stem Strength of Cut Gerbera (Gerbera jamesonii ‘Bayadere’)

Photosynthetic parameters and stem strength of Gerbera jamesonii ‘Bayadere’ plants were studied after foliar application of calcium chloride (0, 0.5, 1, and 1.5 g l-1) under natural light (NL), red light LEDs (R), blue light LEDs (B) and red + blue light LEDs (RB). Chlorophylls content was increased under LED lights and foliar application of calcium chloride. The maximal quantum yield of PSII efficiency (Fv/Fm) and performance index (PI) reached the lowest value under NL conditions. Photosynthesis rate, stomatal conductance, and transpiration rate (E) showed the highest values using RB lighting. Plants grown under the RB light and sprayed with calcium chloride exhibited the lowest leaf nitrate compared to NL conditions which resulted in the highest leaf nitrate content. The higher the nitrate content, the lower the stem strength is expected. However, calcium content of leaves showed the opposite trend. Sprays of 1.5 g l-1 calcium chloride under RB lighting significantly increased flower stem strength and reduced stem bending compared to non-treated plants. In summary, RB lighting along with foliar application of calcium chloride enhanced growth and flower stem firmness of studied cut gerbera.