Mowing height, nitrogen rate, and biostimulant influence root development of field-grown 'TifEagle' bermudagrass

Abstract

As golfers demand higher quality golf green putting surfaces, researchers continue to seek improved turfgrass cultivars. One such improved cultivar is 'TifEagle' bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy], which is an improvement over traditional bermudagrass cultivars such as 'Tifgreen' and 'Tifdwarf' due to its ability to tolerate mowing heights of ≤3.2 mm for extended periods. One observed disadvantage of 'TifEagle' is its lack of a deep, dense root system compared to previous bermudagrass cultivars. This field study measured mowing height, N rate, and biostimulant product effects on 'TifEagle' rooting. Three mowing heights (3.2, 4.0, and 4.8 mm), three N rates (12, 24, and 48 kg N/ha/week), and two cytokinin-centaining commercial biostinaulant products (BIO1 and BIO2) were examined. Plant responses measured were root length density (RLD), root surface area (RSA), thatch layer depth (TLD), and turf quality (TQ). Increasing mowing height from 3.2 to 4.0 mm increased RLD by >11%, RSA by >11%, and TQ by >17%. Increasing N rates from 12 to 24 kg N ha-1 week-1 increased RLD by >17%, RSA by >26% and TQ by >16%. No effect on RLD was observed after the first year of biostimulant use, however, after the second year, BIO1 increased RLD by >11% when applied with the lowest rate of N (12 kg N/ha/week). Higher mowing heights (4.8 and 4.0 mm) increased TLD >6% compared to the lowest mowing height (3.2 mm), and higher N rates (48 and 24 kg N/ha/week) increased TLD >3% compared to the lowest N rate (12 kg N/ha/week). Overall, a mowing heights ≥4.0 mm, N rates ≥24 kg N/ha/week, and long-term use of a cytokinins-containing biostimulant had a positive effect on 'TifEagle' rooting.