775 PB 383 A LEACHING FRAME FOR DETERMINING MEDIA RETENTION OF DRENCH-APPLIED PLANT GROWTH REGULATORS

in HortScience
Authors:
Jesse R. QuarrelsDepartment of Plant and Soil Sciences, Box 9555, Mississippi Agricultural and Forestry Experiment Station, Mississippi State, MS, 39762

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Steven E. NewmanDepartment of Plant and Soil Sciences, Box 9555, Mississippi Agricultural and Forestry Experiment Station, Mississippi State, MS, 39762

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A leaching frame was constructed to detect residual plant growth regulators in media. The table was 0.9 × 1.8 m and designed to hold 40 10-cm diameter by 30-cm PVC cylinders. Each cylinder was cut lengthwise in half and resealed with duct tape. Rooted cuttings of `Freedom' poinsettias were planted into each cylinder using two media combinations: 2 vermiculite: 2 peat moss: 1 pine bark and 2 vermiculite: 1 peat moss: 2 pine bark (by volume). Four growth regulator treatments were applied to the medium two weeks after transplanting: control, 0.25 mg paclobutrazol, 0.25 mg uniconazole, and 0.125 mg paclobutrazol applied as spike. After plant growth was recorded, the cylinders were removed and sliced lengthwise. Snapdragon plugs were then transplanted into the medium along the length of the cylinder to determine if any residual paclobutrazol remained. Paclobutrazol and uniconazole reduced stem length. The presence of pine bark in the media reduced the effect of the plant growth regulators.

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