| Centipedegrass(Eremochloa ophiuroides(Munro)Hack.)is an important warm-season turfgrass originated from China.It has abundant germplasm resources and tolerance to extensive management,and is widely used as turfgrass for greening lawn.DUS test is an examination of Distinctness,Uniformity and Stability for new varieties of plants,which is technical and authoritative basis for new plant varieties protection.DUS guideline is essential in DUS testing,however,there was no DUS testing guideline for centipedegrass in China at present,which led to chaotic utilization of centipedegrass varieties.Morover the breeders' rights and interests can not be protected.Therefore the development,breeding and utilization of centipedegrass germplasm resources in China are limited greatly.Based on revalant plants DUS testing guidelines,16 centipedegrass were collected and 23 characteristics were meassured for two growth cycles,the DUS testing guideline for centipedegrass had been formulated.'Huanan' and 'I28B' centipedegrass,which have different green period,were selected to assess the response of photosynthesis of centipedegrass for cold stress,relevant fluorescence parameters of PS? and PS? were measured under 5 different temperatures of 25?,20?,15?,10?,5? so as to compare the sensitivity of 2 photosystems to cold stress with different temperatures.These findings will provide evidence to reveal the mechanism of physiological changes during centipedegrass leaf senescence in cold stress.In addition a pot experiment under different lower temperatures was conducted to determine the the effect of iron and calcium on cold resistance.25 m M Ca Cl2,1% iron-containing foliar fertilizer,25 m M Ca Cl2 and 1% iron-containing foliar fertilizer were applied to centipedegrass leaves.Greenness of leaves,chlorophyll content,relative water content,electrical conductivity and proline content were measured to assess cold resistance of centipedegrass.These results could provide references for the management and maintenance of centipedegrass in winter.The main results were as follws:(1)Methods were established for centipedegrass DUS test guideline under the guidance of TGP1/3/7 by Protection of New Varieties of Plants(UPOV)and refernece to centipedegrass DUS test guideline by Japanese Ministry of Agriculture and DUS testing guidelines for other varieties in China.(2)By observing and analyzing of morphological traits of centipedegrass varieties,23 traits were finally selected as characteristics of testing guideline.These characteristics were classified,graded,coded and explained and technology questionnaire were included in the testing guideline.On the basis of the above results,the DUS testing guideline for new varieties of centipedegrass was established.(3)The results of chlorophyll fluorescence characteristics and P700 signal of both centipedegrass varieties indicated that photo-inhibition original site of centipedegrass in cold stress is photosystem ?,which means ? was not sensitive to cold stress,whereas cold stress mainly inhibited the activity of photosystem ?.When temperature dropped to 10°C,the photo-protective mechanism of PS? in centipedegrass mainly relying on Xanthophyll cycle,rapidly weakened.The temperature of 10°C cold stress caused centipedegrass PS? photo-inhibition.However the photo-protective mechanism of PS?,relying on cyclic electron transport,was rapidly activated.Meanwhile,activity of photosystem ? of 'Huanan' centipedegrass was higher than 'I28B' centipedegrass,and 'Huanan' centipedegrass had higher photo-protective and lower photo-inhibition.It was concluded that 'Huanan' centipedegrass has stronger cold resistance than 'I28B' centipedegrass.(4)Based on several physiological indexes,centipedegrass cold resistance was assessed by the membership degree of fuzzy.The result indicated that 1% iron-containing foliar fertilizer was optimal fertilizer to enhance cold resistance of centipedegrass,followed by 25 m M Ca Cl2 and 25 m M Ca Cl2 with 1% iron-containing foliar fertilizer. |
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