Mineral nutrition and in vitro growth of Gerbera hybrida (Asteraceae)

The effects of mineral nutrient were examined on in vitro growth of Gerbera hybrida (G. jamesonii x G. viridifolia), specifically Gerbera hybrida cv. Pasadena. Four types of experiments were conducted to quantify the effects of mineral nutrients on four in vitro growth responses (quality, shoot number, leaf number, and shoot height) of gerbera and included groups of mineral nutrients (macros/mesos, micros, and Fe), individual salts (CuSO4 center dot 5H(2)O, MnSO4 center dot 4H(2)O, ZnSO4 center dot 7H(2)O, and Fe/EDTA), and the specific ions NO3 (-), NH4 (+), and K+. Experiments included mixture-amount designs that are essential for separating the effects of proportion and concentration. Highly significant effects were observed in all experiments, but the mineral nutrients with the largest effects varied among the four growth responses. For example, leaf number was strongly affected by the macronutrient group in one experiment and by NH4 (+) and K+, which were in the macronutrient group, in the NO3 (-)/NH4 (+)/K+ ion-specific experiment, whereas quality was strongly affected by the micronutrients ZnSO4 and Fe/EDTA. Because mineral nutrient effects varied significantly with the response measured, defining an appropriate formulation requires a clear definition of "optimal" growth.