Chlormequat chloride and ethephon affect growth and yield formation of conventional, naked and dwarf oat

Abstract

Plant growth regulators (PGRs) are not usually applied to oat (Avena saliva L.) crops. This study was designed to test whether the antigibberellin chlormequat chloride (CCC) and ethylene-releasing ethephon sprayed on to oat foliage represent potential agents for manipulation of yield formation under northern growing conditions. Effects of these PGRs on yield components and tiller growth and productivity were examined in detail. This study included a long-strawed landrace, a modern standard height cultivar, two naked (A. sativa ssp. nuda L.) and two dwarf oats. Field experiments were conducted at Viikki Experimental Farm, University of Helsinki, in 1995 and 1996. Chlormequat chloride was sprayed at the two-node stage and ethephon when the flag leaf ligule was just visible on the main shoot. Various traits characterizing growth and yield formation were assessed. Chlormequat chloride increased grain yield by 0% to 13% depending on cultivar and year, while ethephon most often decreased it by up to 17%. No lodging occurred and the recorded increase in grain yield of CCC treated plants was not therefore due to prevention of lodging. However, CCC treatment resulted in more panicles per square meter and in 1995 tillers contributed more to grain yield. Ethephon treated plants had less grains per main shoot panicle, lower panicle filling rate (PFR) and parallel decreased harvest index (HI). Stem elongation of dwarf oat was enhanced by CCC, in contrast to that of conventional and naked cultivars.