Effect of Paclobutrazol Application Time on Growth, Yield and Starch Content of Two Cassava Cultivars under Rainfed Conditions of Northeastern, Thailand

Abstract

The purpose of the present study was to investigate the effect of paclobutrazol (PBZ) application time on growth, yield and starch content of cassava under rainfed conditions. A split-plots design was set up with four replications. The main-plot consists of two cassava cultivars (CMR and RY-7) and three PBZ application times (90, 135 DAP and two combined 90 and 135 DAP) in comparison with no paclobutrazol application (control) assigned as sub-plots. The study showed that all PBZ application times reduced plant height. PBZ single application at 135 DAP or two combined application at 90 and 135 DAP increased leaf number per plant and leaf area index. The maximum storage root yield was obtained when PBZ applied at 135 DAP over without PBZ application (control) by 46% in the present study. PBZ application at 90 DAP combined with 135 DAP produced the highest starch content of the storage roots. In the present experiment, two cassava cultivars did not show a significant difference on growth, yield and starch content in storage root.