Effect of a biostimulant on bermudagrass fall color retention and spring green-up

[EN] Field research was conducted in 2017-2019 on "Princess 77" bermudagrass (Cynodon dactylon (L.) Pers.) to determine whether an amino acid based biostimulant program applied in the late season (October-November) and early season (March-April) could extend fall color retention (FCR) or hasten the spring green-up (SGU), respectively. Bermudagrass was treated with the biostimulant under five different managements: non-treated; 6 times at 5 L ha(-1) weekly; 3 times at 5 L ha(-1) in a 14-day interval; 6 times at 10 L ha(-1) weekly; and 3 times at 10 L ha(-1) in a 14-day interval. Normalized difference vegetation index (NDVI) and visual ratings (turf green color and percentage of green coverage in the subplot) were determined weekly, and turf clipping dry weight for the SGU studies. At the end of the FCR studies (2017 and 2018), there was no effect of the biostimulant; although, some isolated positive effects were detected during the experiment in 2017 on bermudagrass treated weekly at 10 L ha(-1) for NDVI. However, there was a slight positive effect on SGU when this physiological process occurred slowly (year 2018) and the biostimulant was applied weekly at 10 L ha(-1) (4.4 kg N ha(-1)), compared to another performed management and warmer years (2017 and 2019).