Plant Height and Yield Responses of Rice to Paclobutrazol1

Abstract

AbstractLodging of rice decreases speed and efficiency of mechanical harvest of rice (Oryza salivaL. ‘Starbonnet’). A 3‐yr field study was conducted at Stoneville, MS, on a Sharkey clay soil (Vertic Haplaquept) to determine if rice height and lodging could be reduced with a growth regulator. Paclobutrazol [(2RS,3RS)‐1‐(4‐chlorophenyl)‐4,4‐dimethyI‐2‐1,2,4‐triazol‐1‐yl‐)penta‐n‐3‐ol)] was applied at 0.14 and 0.28 kg a.i./ha 2 weeks before or 2 weeks after panicle initiation, and at 0.07, 0.14, and 0.28 kg a.i./ha at panicle initiation. Application of 0.28 kg a.i./ha of paclobutrazol 2 weeks after panicle initiation reduced rice height each year and increased rough rice yield in 2 of 3 yr. Lodging, which occurred in only 1 of 3 yr, was significantly decreased with 0.28 kg a.i./ha of paclobutrazol applied either at panicle initiation or 2 weeks after panicle initiation. Increasing preflood N rates to 168 kg N/ha plus applications of paclobutrazol did not consistently increase yields