Winter cereal responses to dose and application timing of trinexapac-ethyl

Abstract

Trinexapac-ethyl (TE) is a plant growth regulator commonly used in cereal production systems. It retards plant growth by inhibiting gibberellin (GA) biosynthesis, thereby reducing the risk of stem lodging. Lodging at the latter stages of crop development can compromise grain yield and quality. Thus, application of TE may protect yield and quality in winter cereals. A field study was conducted from 2014 to 2017 across the Canadian Prairies to determine the effects of TE dose and application timings on lodging, canopy architecture, grain yield, and quality of winter cereals. Trinexapac-ethyl treatments consisted of 0.6× (60 g a.i. ha−1) and 1× (100 g a.i. ha−1), which were applied to two winter wheat (Triticum aestivum L.) cultivars, 'Flourish’ and ‘Moats’, and a fall rye (Secale cereale L.) cultivar ‘Hazlet’, at Feekes 5 and 7 growth stages. Compared with the control, TE application increased grain yield by 3–8%, reduced plant height by 5–10%, and shortened internode length. Plant height reductions were most notable when TE was applied at the 1× rate at Feekes 7. The most responsive crop was fall rye, which could be expected given its tall stature relative to the wheat cultivars. Most of the tested environments, including irrigation, did not induce heavy stem lodging; therefore, observations of positive yield responses in the absence of lodging were unexpected. Our findings suggest that there is a role for TE in winter cereal production systems, provided the magnitude of crop responses justifies the added input costs.