Study On Influence Of Appling Plant Growth Regulators On Growth And Nitrogen Requirement Of Kentucky Bluegrass And Tall Fescue

Three types of new PGRs, Trinexapac-ethyl, Paclobutrazol and Ethephon. trade name used:Primo. Trimmit and Proxy, had been adopted in this experiment. The mode of action of these growth-inhibiting compounds are inhibiting cell elongation by reducing production of gibberellic acid, and consequentially reduce mowing frequency. Each type of chemical was applied at three concentrations to potted cold-seasonal lawn of Kentucky bluegrass and tall fescue(Pixie and Nuglade ), and the height, clipping weights, chlorophy 11 content and the total N of the turfgrass clipping in this experiment.Primo could inhibit the growth of Kentuchy bluegrass and tall fescue, and the highest conentrations showed the best effect. There wrer some differences of Primo's growth regulating effect on Kentuchy bluegrass and tall fescue. Growth suppression of Kentuchy bluegrass occured at 21 days after application and lasted for 30 days. However, the growth suppression of tall fescue could be obviously discovered after 7 days of application(P<0.05), and the duration of activity could last 40 days. Therefor, Primo's effect on tall fescue was better than on Kentuchy bluegrass, and the duration of activity was much longer. Trimmit had no evident effect on Kentuchy bluegrass and tall fescue. Proxy had good effect on Kentuchy bluegrass, but it had no evident effect on tall fescue.Primo were highly effective in reducing clipping weights of Kentuchy bluegrass and tall fescue, and the highest conentrations had the best effect. Clipping weights treated with the Proxy highest rate were reduced to some extent, but it had little effect on tall fescue. Trimmit have no evidently effect on clipping weights of Kentuchy bluegrass and tall fescue.chlorophy 11 content of Kentuchy bluegrass treated with the 3 types of chemical was higher than CK, but chlorophy11 content of tall fescue treated with the 3 types of chemical was lower. Chlorophy11 content treated with low and high rates of Primo and high rate of Trimmit was evidently higher than CK, but Primo was the only that did not decrease the chlorophy11 content of tall fescue(P<0.05). Only Proxy increased the chlorophy11 a/b value of Kentuchy bluegrass, but Primo had best effect on tall fescue.Primo,Trimmit and Proxy all had some effect on Kentuchy bluegrass's total N of the turfgrass clipping. But which all had no effect on tall fescue's total N of the turfgrass clipping.