Effect Of Seed Dormancy Broken,Paclobutrazol And Trinexapac-Ethyl On The Turf And Physiological Characteristics Of Poa Pratensis

The study of low temperature, H2O2、H2SO4and breaking lemma treatments on breaking seed dormancy of the cultivar Best of Poa Pratensis, and influences of paclobutrazol and trinexapac-ethyl on its turf characters were conducted. The turf character and the cell membrane permeability of Best after spraying paclobutrazol and trinexapac-ethyl were explored under the effects of high(40℃),low(-20℃) temperature and physiological characteristics under drought (72h) stresses conditions, respectively.The result of different treatments on breaking dormancy of BEST seeds showed that the treatment of breaking lemma was better than the other3treatments considering the cost and establishing turf speed. The germination potential was84.67%, and the germination rate was90.67%, which were significantly higher than that of the control(P<0.05). We should pay attention to not damage the seed embryos when breaking lemma, otherwise the germination rate was decreased because the seed embryos was broken.The height and leaf width of Poa Pratensis were significantly inhabited springing Paclobutrazol and trinexapac-ethyl. The heights of P1, P2and P3theatments respectively lowered7.81、9.48、9.05mm than that of control, and The heights of T1, T2and T3were lowered18.1、16.54、11.39mm than that of control.The leaf widths of P2, T2and T3treatments decreased0.63mm,0.71mm and0.75mm than that of control, which was significantly narrower than that of the control (P<0.05) on the40th day. Turf color of P1and T3treatments presented light green, which made the turf not to be beauty. The root/shoot ratio of P1, P2, and P3increased by51.50%,66.10%and49.40%, respectively. The root/shoot ratio of T1and T2had no difference to the control (P>0.05). The root/shoot ratio of P2was significantly higher than that of the control.Under the low or high temperature stress, the cell membrane permeability of all theatments were increased compared with that under the room temperature. The cell membrane permeability and damage rate of P1, P2, P3,T1and T2were different, which were significantly lower than that of the control at the same temperature. Under the low temperature stress, the effect of spraying paclobutrazol on decreasing the cell membrane permeability was better than that of trinexapac-ethyl, but under the high temperature stress the result was opposite.The effect of drought stress on physiological characteristics of ’Best’ after spraying paclobutrazol and trinexapac-ethyl was studied. The result showed that on the10th and40th day, POD activity of P2treatment was higher than other treatments, and POD activity of T1, T2and T3treatments was significantly higher than that of the control, but lower than that of P1and P2treatments. Malondialdehyde (MAD) content was descending gradually. The descending speed of MAD content of trinexapac-ethyl was higher than that of paclobutrazol. On the40th day, MAD content of T2and T3treatments was the most lower. The content of P1, P2and T1treatments was no significant difference. During the whole experiment, proline content was rising first, then was descending, and the effect of P1and T2treatments was stronger than that of others.Considering plant height and leaf width, leaf color, cell membrane permeability and physiological characteristics of Poa Pratensis, the concentration (200mg/L) of paclobutrazol and the concentrations (100μl/L and140μl/L) trinexapac-ethyl were recommended in practice in order to relieve the stress caused by high temperature, low temperature or drought.