| High temperature is the major factor limiting growth of cool-season turfgrass in transitional zones. The optimum temperature for cool-season turfgrass ranges from 15*C to 24*C for shoot growth and 10°C to 18°C for root growth. It can be evergreen year round in cool climate zone. In Yangtze River transitional zones it has a long green period. But in summer, it can hardly survive because of heat stress. A cool-season turfgrass (Festuca arundinecea Schreb.cv.Huntdog 5), which has strong invasion , heat-tolerance and high quality.is introduced to study heat-resistance in the potted experiment in the experimental farm of Fujian Agriculture and Forestry University in septemper ,2003.The re-split plot design with three factors and three levels was employed to study the effect of different treatments with different of Phoshorus,potassium, plant growth retardant (PP333) applicated rates on the activities of protective enzymes including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT),permeability of plasma membrane (PMP),contents of malondialdehyde (MDA), chlorophyll(Chl), carotenoids , ascorbic acid(AsA),proline (Pro),soluble protein(SP),soluble sucrose(SS),total Phenols,flavonoid, as well as,N,P and K in the leaves of Festuca arundinecea, The main result abtained from this experiment were as follows:It showed that Festuca arundinacea possessed different heat-resistance and their own physiological and biochemical mechanisms in 27 different treatments with different phosphorus, potassium and PP333application rates during the heat stress. The best treatment , showing heat-resistance, is the treatment P2K3C2(P2=60 kg/hm2,K3=140 kg/hm2 ,C2=250 mg/L).By which the protective enzyme activities(SOD,POD,CAT) and the antioxidants.AsA were the highest, leading to decreased of MDA content and PMP. The result also indicated that the contents of carotenoid ,Pro, soluble sucrose(SS) and soluble protein(SP) in Festuca arundinacea were the highest. This implied that Festuca arundinacea had the strongest ability resistant to the heat stress in the treatment. It was also indicated that Festuca arundinacea contained higher amounts of chlorophyll in leaves and absorbed more N^ P> K elements in P2K3C2 treatment as mentioned above compared with other treatments in Festuca arundinacea ,which were attributed to its higher root activity and photosynthesis .It therefore suggested that Festuca arundinacea was the stronger heat-resistant cultivar when pretreated with P2K.3C2 in summer. It was also found that the contents of the total Phenols and flavonoid were increased by the heat stress. Which are favorable to decrease the free radical contents and in turn reinforced the stability of protective membrane in Festuca arundinacea.Conse<\\ient\y, it strengthened the resistant ability of Festuca arundinacea to heat stress in summer.Therefore ,the treatment with P2K3C2 was the better practice to significantly increase heat-resistance and postpone the senescence of Festuca arundinacea plants under the stress of high - temperature environment.Finally, in the premise of successfully over aestivating regulated by cutivative practice, the comprehensive use of fertilizer and plant growth retardant was recommended. By which it is expected to extend the green time of Festuca arundinacea and offer some reference for the cool-reason turfgrass to... |
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