Optimization of paclobutrazol dose for mitigation of water-deficit stress in rice (Oryza SativaL.)

Abstract

The objective of the present study was to assess and optimize the paclobutrazol (PBZ) dose for mitigation of adverse effects of water deficit stress in rice. Paclobutrazol (PBZ), a triazole compound, has been proven to protect plants against abiotic stresses. As a result, an experiment was conducted with three rice varieties, namely N22, IR64 DTY1.1, and IR64, to identify the optimal dose under both mild and severe water deficit stress (WDS) at both vegetative and anthesis stages. Exogenous PBZ (30, 60, 90, and 120 ppm) was applied to plants just before imparting water deficit stress. The highest augmentation of relative water content (RWC), membrane stability index (MSI), total chlorophyll, chlorophyll stability index (CSI), and abscisic acid (ABA) was observed at 90 ppm of PBZ. Based on a curve-fitting analysis of the physiological responses of three rice cultivars to PBZ, the optimum dose was estimated to be around 100 ppm.