We would like to acknowledge Semillas Dalmau SL for seeds and Biotecnolog ıa del Mediterr aneo SL for providing biostimulants.

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).

Field research was conducted to compare the effect of different nitrogen (N) fertilization strategies on an established tall fescue (Schedonorus arundinaceus 'Braveheart') turf for 1 year to study the possibility of maintaining an acceptable quality at a low N rate. Treatments were: mineral fertilizer (MF), urea (U), amino acid-based biostimulant (B-200), all applied at 200 kg N ha -1 yr -1 ; osmoregulator glycinebetaine (GB) and the same biostimulant (B-20), applied at 20 kg N ha -1 yr -1 ; mixtures B-20 and GB, and both combined with MF (B20+MF and GB+MF), applied at 100 kg N ha -1 yr -1 . Turf quality and color, and the NDVI, were determined weekly, while dry clipping weight was obtained monthly. All the N fertilization programs benefitted tall fescue in all the evaluated characteristics compared to B-20. GB was beneficial when applied alone (20 kg N ha -1 yr -1 ) or combined with MF. The reduction from 200 to 100 kg N ha -1 yr -1 in the two combination programs (GB+MF and B20+MF) resulted in statistically similar turf quality compared to mineral fertilization.

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