Effects Of Three Plant Growth Regulators On The Growth Of Kentucky Bluegrass (Poa Pratensis L.) Under Salt Stress

To explore the effects of exogenous gibberellin (GA3), salicylic acid (SA) and chitosan (Cs) interaction of three plant growth regulators on salt tolerance of Kentucky bluegrass (Poa pratensis L.) in this experiment, a variety of Kentucky bluegrass (Midnight) was used as study material. After the treatment of three the concentration of P1 (GA310 mg/L+SA 30 mg/L+Cs 100mg/L), P2 (GA330mg/L +SA 60 mg/L+Cs 250mg/L), P3 (GA360mg/L+SA 90mg/L+Cs 500mg/L), Some physiological indexes including the leaf relative water content, electrical conductivity (EL), malondialdehyde (MDA), proline, soluble sugar, soluble protein, hydrogen peroxide (H2O2), antioxidant system (SOD, POD, CAT, APX) were measured. The results and conclusions are as follows:1. Under salt stress, P2, P3 pre-treatment significantly increased relative water content of Kentucky bluegrass leaves and later only P2 treatment was significantly higher than that of RWC only salted. Impact on the electrical conductivity, the whole process of P1 treatment, P2 treatment were significantly (P<0.05) inferior to only NaCl treatment, indicating that it could decrease electrolyte leakage, maintain the stability of the cell membrane structure and function under salt stress. Impact on MDA and electrical conductivity were similar, and its content were significantly (P< 0.05) lower than that of NaCl treatment group alone in the whole stress period, especially P2 treatment group having a maximum reduction. Throughout the stress period, H2O2 contents of P2, P3 and P1 treatment group were significantly lower (P< 0.05), and P2 treatment had the greatest reduction degree, thus reducing the oxidative damage of cell membrane.2. Plant growth regulators also had different degrees of increase in the content of osmotic substances, and improved the osmotic adjustment ability of cells. Under salt stress, proline, soluble sugar, and soluble protein contents of P1, P2, P3 treatment group had varying degrees of increase, but P2 treatment increased the maximum degree, reached a significant level (P< 0.05).3. Plant growth regulators significantly improved antioxidant system activity under salt stress, and P2, P3 treatment made a big difference to enzyme activities of POD, APX, and CAT, significantly enhancing the three enzyme activity and achieving significantly (P< 0.05) level, in which the P2 treatment reached the maximum degree. PI and P2 significantly enhanced the enzyme activity of SOD (P< 0.05), and showed the large effects of growth regulators with low concentration on the activity. To sum up, in the three treatment groups, P2 treatment was conducive to improving the activity of anticxidant enzymes of Kentucky Bluegrass under salt stress, thereby improving the salt tolerance of turfgrasses.