Trinexapac-ethyl alters the expression of descriptors for identifying white oat cultivars

Trinexapac-ethyl reduces lodging in white oat, but its use in seed production fields requires knowledge of its impact on the expression of descriptors, under penalty of compromising the identification of cultivars. In this work, six white oat cultivars of different stature classes (Low: Brisasul and URS Taura; Medium: IPR Artemis; High: URS Altiva, URS Brava and URS 21) were evaluated for the state of expression of descriptors in response to the application of 100 g a.i ha-1 of trinexapac-ethyl when the primary stalk had the first visible node and the second perceptible node. Over two years, the experiments were carried out with different rainfall conditions (2017/2018), in a split-plot design, with three replications. The phenotypic variability in response to product application varied according to cultivar and year. Seven out of 23 descriptorschanged the state of expression in response to trinexapac-ethyl, in greater magnitude for plant length, followed by lemma length and panicle branching position, cycle, floral and glume axis lengths, and density of plants panicle. Trinexapac-ethyl reduced plant length, floral axis and glume, anticipated flowering, increased panicle density and lemma length. Regardless of year, the cultivars with the greatest phenotypic stability to the application of trinexapac-ethyl were Brisasul (96%) and Taura (91%), and the least stable was URS Altiva (83%). The stability of the other cultivars was yeardependent, with the greatest change in phenotypic expression in the year of lower water availability.