EFFECTS OF NITRATE AND CYTOKININ ON CREEPING BENTGRASS UNDER SUPRAOPTIMAL TEMPERATURES.

Heat stress reduces creeping bentgrass performance in temperate to sub-tropical climates. The research objective was to characterize effects of nitrogen (N) and cytokinin (CK) on creeping bentgrass under heat stress. In a 38°C/28°C chamber, grasses were treated with two nitrogen (2.5 and 7.5 kg N ha−1) and three CK rates (0, 10 and 100 μM) biweekly. Grass grown at high N had better turf quality, higher photochemical efficiency (Fv/Fm), normalized difference vegetation index (NDVI), and chlorophyll concentration at d15 and 28 than low N. CK increased NDVI at d15, with Fv/Fm of the CK100 treatment being 18% higher than that of CK0 at d28. Under high N with 100 μM CK, roottrans-zeatin riboside (tZR) and isopentenyl adenosine (iPA) were 160% and 97% higher than under low N without CK, respectively. These results demonstrate positive impacts of N and CK on creeping bentgrass under heat, with N playing a dominant role. [ABSTRACT FROM PUBLISHER]