| As one of the most important warm-season turfgrasses, bermudagrass(Cynodon dactylon) was widely distributed in tropical, subtropical and temperate regions, but also has a wealth of genetic variation. In China, Cynodon dactylon was usually used to establish turf for different purposes in the south region, but it was rarely used to establish turf in the north area. Its primary reason is the lack of varieties which have high cold resistance and adaptability to climate and ecological conditions of this region. This research included three main parts. Firstly, the growth habits, ecological adaptability and turf characteristics of ‘Baoding’ bermudagrass and ‘Handan’ bermudagrass selected from 52 germplasms were evaluated and the cultivar ‘Riveria’ released in America was used as the control by regional experiments. Secondly, the genetic diversity and relationships of 34 wild bermudagrass accessions from Hebei province were analyzed by using molecular markers. Thirdly, the study on techniques for the turf establishment and maintenance of the two excellent varieties selected from wild germplasm resources was carried out. The main results were as follows:(1) Compared with the control, two varieties provided better turf characteristics and quality than the control variety, which were named ‘Baoding’ and ‘Handan’ bermudagrass respectively.‘Baoding’ bermudagrass was the lowest natural growth height and was only 9.7 cm in average because of it’s strongly stolonious habit which resulted in the least clipping yields among the tested materials. It provided high density and highest turf quality with an average rating of 7.0. ‘Baoding’ bermudagrass represented excellent turf characteristics such as lower height, better texture, dark green color and few mowing frequency.‘Handan’ bermudagrass represented the significant characteristics such as longer green period, rapidly vegetative growth, higher capability of pest resistance and recovery. Its plants were semi-stolonious and spreaded rapidly at an average lateral growth rate of 2.52 cm per day in July. Among the tested materails, ‘Handan’ bermudagrass regreen earlier in spring and went dormancy latest which resulted in the longest green period of 210 days in Baoding region.(2) SSR were used to detect the genetic diversity of 34 wild accessions of Cynodon dactylon collected from Hebei Province and two other varieties(Riviera and ‘Chuannan’ bermudagrass). The results showed that 33 primer pairs produced a total of 351 bands, among which 295 bands were found to be polymorphic, averaged 10.64 bands per primer pair. The percentage of polymorphic bands in average was 84.05%. The Nei’s genetic similarity coefficient(GS) of the tested accessions ranged from 0.479 to 0.969, and the average GS was 0.677. The accessions were divided into four groups based on cluster analysis when the GS was 0.67.(3) SRAP and TRAP were employed to analyze the genetic diversity and relationships of 36 bermudagrass(Cynodon dactylon) accessions montioned above. Ten primers pairs of SRAP and TRAP produced a total of 186 and 161 bands, including 156 and 132 polymorphic bands, averaged 15.6 and 13.2 polymorphic bands per primer pair, and the percentages of polymorphic sites were 83.44% and 81.02% in average, respectively. Combined the both markers with cluster analysis, the GS among all accessions ranged from 0.519 to 0.983 and was 0.7 in average. When the GS was 0.68, the 36 accessions were classified into four distinct clusters.(4) The clustered result based on SSR markers and the clustered result based on combining SRAP and TRAP markers were similar, but there are also obvious differences. The results indicated that the accessions from the same origin frequently were clustered into one group, but some accessions from the different origin were also crossed and separated. Combined above-mentioned markers with cluster analysis, the 36 accessions were classified into five distinct clusters.The three clustered results indicated that there was substantial genetic diversity among the Cynodon dactylon germplasms in Hebei province. The correlation between two markers among three molecular markers was remarkable, but the correlation coefficients were different, and the correlation between SSR and SRAP was higher.(5) Under the atmospheric conditions of Baoding region, the critical stage to bermudagrass turf was the middle of July in order to establish successfully and guard against winter injury. During mid-may to mid-july, bermudagrass turf could form a complete cover within 30 to 40 days by stolonizing at the rate of 100 to 200 gram stolons per square meter or plugging at the rate of 50 to 200 gram stolons per square meter with the cuitivar ‘Baoding’ and ‘Handan’ bermudagrass without water stress and nutrient deficiency.(6) After application of paclobuturazal during the robust growth period, the natural growth height and vertical growth rate of ‘Handan’ bermudagrass were reduced up to 48.8% and 87.8% as compared with the control, respectively. As a result, the clippings and mowing frequency were reduced up to 88.3% and 66.7%, respectively. At the same time, paclobuturazal improved color, density and turf quality of bermudagrass. Based on a comprehensive performace of three years, the application of paclobuturazal at the rate of 300 to 400 mg per square meter on ‘Handan’ bermudagrass in summer was advisable.(7) Close mowing at about 2 cm in combination with proper thatching before green-up in spring or the use of protective covers such as plastic films, non-woven fabrics, felt and black net in winter promoted the soil temperature and improved the green up date was earlier 5 to 12 days than the uncovered plot. As a result, the turf green period was prolonged.(8) During bermudagrass growing season, balanced and sustained fertilization with NPK ratio and rate of 5:3:3 maintained the normal growth of bermudagrass, but also improved turf color, density, and turf quality. The green period of bermudagrass was prolonged. The days of acceptable turf quality increased 73 d, 23 d, 16 d and 114 d than N-deficiency, P- deficiency, Kdeficiency and unfertilized treatments, respectively. |
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