Plant growth regulator effects on red fescue seed crops in diverse production environments

Abstract Strong creeping red fescue ( Festuca rubra L. spp. rubra Gaudin) is a cool‐season perennial turfgrass widely used in temperate and subalpine regions around the globe. Although creeping red fescue turf is tolerant of shade, low fertility acidic soils, and drought conditions, creeping red fescue seed crops grown in optimal growing environments can lodge, ultimately reducing yield in regions where this important turfgrass is grown for seed. To address this issue, we investigated the effects of two plant growth regulators (PGRs), chlormequat chloride (CCC) and trinexapac‐ethyl (TE), on plant height, lodging, and seed yield of strong creeping red fescue over 9 site‐years in the Peace River region of western Canada. The study encompassed 6 site‐years with first‐year stands and 3 site‐years with second‐year stands. The PGRs were applied alone and in a TE + CCC mixture at the two‐node (BBCH 32–33, where BBCH is Biologische Bundesanstalt, Bundessortenamt and Chemische Industrie) and early head emergence (BBCH 51–52) growth stages in first‐ and second‐year stands, respectively. The application of TE, CCC, and their mixture resulted in a differential decrease in lodging and an increase in seed yield in first‐year stands. However, PGRs applied at BBCH 51–52 on second‐year stands had no effect on seed yield but reduced plant height and lodging. This study found a negative correlation between seed yield and lodging. Among the PGR treatments, the CCC + TE mixture was the most effective in reducing lodging and increasing seed yield of strong creeping red fescue.