Paclobutrazol persistence dynamics in mango (Mangifera indica) orchard soil using HPLC and LC-MS/MS analysis

Abstract

Paclobutrazol, a plant growth regulator, is used commercially in soil application to counter the alternate bearing habit of mango (Mangifera indica L.) all over the country. The experiments were conducted during 2020–21 and 2021–22 at ICAR-Central Institute for Subtropical Horticulture, Lucknow, Uttar Pradesh to study the persistence of paclobutrazol in soil and its subsequent uptake in mango fruits using HPLC and validated by LC-MS/MS after its application to tree basin soil of mango cv. Dasheri @2, 4, 6, 8 and 10 g a.i./tree. The residues of paclobutrazol dissipated in soil from its initial values of 10.33, 17.25, 25.71, 50.80, and 62.36 µg/g soil at 0 days to 0.14, 0.30, 0.47, 1.32 and 2.38 µg/g soil after 300 days of application. The dissipation rate in soil followed first-order kinetics with half-life values ranging between 57.75 and 77.00 days. Residues of paclobutrazol were not detected in fully mature fruits harvested after 85 days of fruit set. LC-MS/MS analysis confirmed that the sample peaks corresponded to paclobutrazol residues in mango fruit and soil. Thus, HPLC and LC-MS/MS analysis clearly showed that the paclobutrazol persisted in the soil for longer, but the mature fruits harvested from treated trees were free from its residue even at higher doses and safe for consumption. The response of paclobutrazol to the quality of fruits in terms of phenolic content was also assessed. The paclobutrazol was more responsive in altering phenolic acid composition than the control.