Evaluation of Pre- or Postharvest Application of Some Minerals and Organic Agents on the Growth, Flowering and Vase Life of Rudbeckia hirta, L

The experiments were carried out during 2014 and 2015 summer seasons at the greenhouses of the Experimental Farm of Faculty of Agriculture, Kafr El-Sheikh University. The experiments were conducted in two phases- First one (pre-harvest)- Rudbeckia hirta seedlings were transplanted during the first week of May to 30 cm diameter plastic pots filled with a soil mixture of clay and sand (1-1, v-v). Pots were divided in two equal groups, the first one, plants were foliar sprayed with one of the following-- Distilled water for the control treatment, CaCl2 (125, 250, 375 mg·L-1), NiSO4 (30, 45, 60 mg·L-1), CoCl2 (50, 75, 100 mg·L-1), K2SiO3 (100, 150, 200 mg·L-1) and SA (100, 150, 200 mg·L-1) at 60, 45, 30 and 15 days before harvest. The second group was without pre-harvest application assay (untreated plants).Second phase (postharvest) was conducted in two different methods as follows- First method, flower stems resulted from each pre-harvest treatment were preserved in 250 mL graduated test tube filled with 200 mL of standard holding solution consists of sucrose (4%) + 8-Hydroxyquinoline citrate (250 mg·L-1). The second method, flower stems resulted from plants without pre-harvest application preserved in holding solution consists of a constant sucrose (4%) and 8-Hydroxyquinoline citrate (250 mg·L-1) beside one of the following additives- Distilled water for the control treatment, CaCl2 (125, 250, 375 mg·L-1), NiSO4 (30, 45, 60 mg·L-1), CoCl2 (50, 75, 100 mg·L-1), K2SiO3 (100, 150, 200 mg·L-1) and Salicylic acid (100, 150, 200 mg·L-1). Results showed that, pre harvest spraying plants with higher levels of K2SiO3 or CaCl2 recorded the highest values for all plant vegetation characters. K2SiO3 followed by SA excelled on others in most flowering aspects. At the post harvest stage, SA, K2SiO3 and CaCl2 exchanged the excellence between them for most vase life measurements. Flowers resulted from plants that preharvest treated was better than those that did not preharvest treated.