UC Davis

In this study, a pilot scale slow sand filtration system was evaluated for biodegradation of the plant growth regulator paclobutrazol from recaptured irrigation leachate in a simulated greenhouse environment. Generated irrigation runoff containing 0.05 mg·L-1 paclobutrazol passed through 1-meter-deep slow sand filter sand beds for a period lasting 120 days. Evaluations through a broccoli hypocotyl length bioassay proved acutely sensitive to low concentrations of paclobutrazol, which is an affordable indicator of paclobutrazol presence in nursery runoff that can be utilized by nursery professionals. The SSF system proved ineffective in complete removal of PBZ as the bioassay indicated similar hypocotyl lengths grown with leachate before and after filtration.