Drought reaction and rooting characteristics in response to plant growth regulators on Poa pratensis cv. Barimpala

Kentucky bluegrass (Poa pratensis cv. Barimpala) is the most widely used turfgrass in Iran. Two studies were conducted to evaluate the effects of plant growth regulators (PGRs) and drought on turf performance and to assess the measuring of root characteristics. Kentucky bluegrass seeds were cultivated on sandy-loam soil, and then three levels of irrigation (at 2, 5, 10 days interval) were performed until PGR application. After 7 weeks, soil was removed and root characteristics were measured by two methods. Results indicated that trinexapac-ethyl (TE) enhanced turfgrass performance. Reduction of total clipping yield was 47% and 58% in concentration of 0.2 kg ha(-1) TE and 0.4 kg ha(-1) paclobutrazol, respectively, TE didn't show,my inhibiting effect in the first measuring of root characteristics. Application of paclobutrazol resulted in significant decrease in root length density (RLD). In the second method, TE concentration of 0.2 kg ha(-1) significantly decreased RLD. Meanwhile, paclobutrazol had no considerable effect on root characteristics.