Abstract

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.

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