| Perennial ryegrass is a important cool-season turfgrass with many advantages, such asdeveloped root system, strong tillering ability, quick establishment speed, good wear toleranceand so on. But it’s cold resistance is very poor and regarded as the most sensitive cool-seasonturfgrass to low-temperature stress. Therefore, it has enormous economic and social benefits toimprove the winter hardiness of perennial ryegrass and increase it’s useable range. Thematerials of this research are nineteen mutagenic lines from one seed of perennial ryegrass‘Derby’ and one perennial ryegrass variety ‘Pinnacle’ with good winter hardiness. We havecarried out two-years investigation of their winter hardiness and gain five well-behaved lines.Besides, we also have conduct two experiments under artificial and field low-temperaturestress, and measured some indexs related to cold resistance, such as LWC, RMP, MDA, Pro, SP,SS, RS, SOD, POD, CAT, Chl, Fv/Fm and so on. By principal component analysis andmembership function calculating, we have made comprehensive assement of all experimentmaterials in two low-temperature stresses. The study is aimed at acquiring mutagenic lines withgood cold resistance, and providing basis for mutation breeding of plants and cold resistanceresearch. The main research results are as follows:1. The investigation results of winter hardiness show that: the experiment materialstransplanted in autumn have similar wither period, returning green period, winter survive rateand so on. While the experiment materials transplanted in summer display differently.‘Pinnacle’ has the longest green period and the highest winter survive rate, while CK14-3weighs against it with strong tillering rate and perform the best in five mutagenic lines; G16-1also has longer green period and highest winter survive rate behave well; G3-2and G10-5withshort green period and low winter survive rate perform poor.2. The LWC of all experiment materials decrease with the decrease of temperature bothunder indoor and field experiments. There is a negative correlation between LWC and cold resistance of perennial ryegrass underartificial low-temperature stress, but no relation is found in field experiment.3. Both under indoor and field experiments, RMP enlarge and MDA content increase withthe temperature decrease. The perennial ryegrass with small RMP and low MDA content hasexcellent cold resisitance.4. All the osmotic adjustment substances increase under artificial experiment; in fieldexperiment, SP content decrease and other substances increase. Pro and RS content arenegatively related to perennial ryegrass’s cold resistance both under indoor and fieldexperiments; under artificial low-temperature stress, perennial ryegrass with good coldresisitance has great change rate of SP content and small change rate of SS content, but thereare no relations under field low-temperature stress.5. Under artificial low-temperature stress, the activity of SOD and CAT enhance,perennial ryegrass with good winter hardiness has low enzymatic activity and large change rate;but under field natural low-temperature stress, the activity of SOD increase, while the activityof POD and CAT decrease. The material with good winter hardiness has large increase rate ofSOD, large decrease rate of POD and small decrease rate of CAT, and all the enzyme activitiesof good cold resistance are low in the whole process.6. Fv/Fm decrease along with the temperature decrease both under indoor and fieldexperiments, the experiment material with small change rate has strong cold resistance. Underfield low-temperature stress, Chl content present the same trend.7. By principal component analysis and membership function calculating, we have madecomprehensive assement of all experimental materials. In two low-temperature stress,‘Pinnacle’ has the highest comprehensive evaluation value, CK14-3takes the second place,G3-2perform the worst. Comprehensiving the above study, CK14-3displays excellent and ispromising to develop as new germplasm with good cold resisitance. |
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