Primary Research On Membrene Fatty Acids And Osmotic Adjustment Of Turfgrasses In Response To Water Deficit

With the social development and urbanization for 30 years in China, lawn is an important part in modern cities. But irrigation water for turf is more and more incompatible with the water supply in cities as increases in green area. Because of Water resources deficit, the beautiful lawn was often under drought stress, which always caused the decrease in turf quality, even the death of it. It has become a bottleneck problem to limit the lawn quality in cities. Therefore, to do the research on the mechanism of drought resistance and select more drought resistant breed is a fundamental way to solve the problems of the contradictory use of water and improvement of lawn quality. Bermuda grass (Cynodon dactylon) and Kentucky bluegrass (Poa pratensis) are widely applied in leisure places and sport fields like gardens and golf courses. The primary research was carried on membrane fatty acids composition and osmotic adjustment in different turfgrasses in response to drought stress. The results were as follows:1. The first study was investigated the genotypic variation in fatty acid composition and unsaturation levels in Bermuda grass('C299', drought susceptible;'Tifway', drought resistant) associated with leaf dehydration tolerance. There was no significant difference on Linoleic acid (C18:2) content in drought resistant'Tifway'between well-watered control and drought stressed treatment under water deficit, but C18:2 content in drought susceptible'C299'decreased significantly under water deficit compared to well-watered control. However, the linolenic acid (C18:3) content declined significantly in both Bermuda grasses.2. Considering the results of Bermuda grass under drought stress, the second study was determined the genotypic variation in fatty acid composition and unsaturation levels in Kentucky bluegrass ('Brilliant', drought susceptible;'Midnight', drought resistant) associated with leaf dehydration tolerance and following water recovery. It showed that no significant difference was detected on C18:2 content in drought resistant'Midnight'between well-watered control and drought stressed treatment under water deficit, but C18:2 content in drought susceptible'Brilliant'decreased significantly under water deficit compared to well-watered control, which was the same changes as that in Bermuda grass. Meanwhile, after re-watering, C18:3 content in drought resistant'Midnight'recovered, but C18:3 content in drought susceptible'Brilliant'continue to decline.3. The third study was to compare the differences of osmotic adjustment (OA) capacity between two cool-season turfgrasses ('Brilliant', drought susceptible;'Midnight', drought resistant) in response to water deficit. The results showed that drought resistant'Midnight'had better OA capacity than drought susceptible'Brilliant', and the proline and water soluble carbohydrates (WSC) were the main contributors to OA. Meanwhile, the increase of WSC in drought resistant'Midnight'could be one of the main reasons for its better drought resistance than'Brilliant'.