Evaluating The Turf Landscape Quality And Study On Cold Resistance Of Native Dichondra Repens In The Southwest Of China

In this paper,23 wild samples of Dichondra repens which are collected from different areas in Sichuan,Guizhou,Yunnan province have been assessed the turf landscape quality. Then, we selected 10 wild samples with higher turf landscape quality to be researched the cold resistance. The main purpose of this experiment was to select excellent D.repens resource with high turf landscape quality and good cold resistance. The results showed that:1. Combining results of eight assessment index such as leaf area, uniformity, leaf color, green period, turf height, establishing velocity, leaf flat degree, pubescence, we can know GD200503 (7.97score),SD200513(7.925score),GD200502(7.28score),SD200308(7.26score),SD200303 (7.255score) list on the top five for the great landscape quality because of their suitable leaf area, uniformity surface, wonderful leaf color and flatly outspreading leaves. They can be used as ornamental turf in the city. SD200407 (4.898 score) get the lowest score for its oversize leaves, uneven leafstalk which lead the turf looking in clutter, short green period and long time to establishment.2. The 23 wild samples of D. repens can be classed to four types: The first type included SD200301,SD200302,SD200405,SD200406,SD200407,SD200309,SD200411,YD200502, which have less landscape quality and list on 17 to 24. The second type included SD200512,GD200501,GD200502,GD200504,YD200505, which list respectively on 13,6,3,11,15. The third type included SD200308,SD200310,SD200513,YD200501,YD200503,YD200504,YD200506,GD200503. Except the YD200506(list on 10), the others are the most landscape quality samples in all the samples; The fourth type included SD200303(list on 5),SD200304 (list on 16),CK(list on 4). 3.Though the correlation analysis between the index of landscape quality and the outcome, we can find that the outcome is extremely significant positive correlation with the uniformity, green period, establishing velocity and leaf flat degree and the correlation coefficient are 0.78,0.82,0.65,0.53 respectively. The outcome is significant positive correlation with leaf area, turf height and pubescence and the correlation coefficient are 0.43,0.41,0.48 respectively. That means the different index make a different contribution to the outcome and the over half index decided the outcome, which means the chosen index are logical and scientific for assessing the landscape quality of D.repens turf.4. During the temperature drop from 10℃to -10℃slowly, the relative electrical conductivity rate will changed like "S" figure. LT₅₀ can be classed to three grade. The first grade is from -0.241℃to-3.98℃, includingSD200308,SD200310,YD200501,GD200501,GD200502; The second grade is from-7.91℃to-8.66℃, including SD00513,YD200503,YD200504,GD200503; The third grade is from-10.19℃to -12.54℃, including SD200303,CK.5.The activities of SOD of D. repen increased then decreased gradually as the temperature drop from 10℃to -10℃. YD200501 has achieved the peak at 5℃, but SD200308,SD200310,GD200501,GD200502 have achieved the peak at 0℃,SD200513,YD200503,YD200504,GD200503 have achieved the peak at-5℃in the end.6.Under the intimidating of low temperature, the MDA content of the D. repen increased like "s" figure with different degree. From the analysis of variance we can find that changes of MDA content of samples are extremely significant(P＜0.01) as the temperature changes. That means the D. repen samples from different areas have different sensitivity to the low temperature. When the temperature drop from 10℃to -10℃, the soluble sugar of most D. repen samples drop, the rise and finally drop, the free praline content rise and then drop.7. Based on the fuzzy subordinate function value of five cold resistance indexes, we can divided the 11 D. repen samples into three types. The first type included five samples: SD200308,SD200310,YD200501,GD200501,GD200502, and they have worst cold resistance; The second type included four samples: SD200513,YD200503,YD200504,GD200503, with medium cold resistance; The third type included two samples: SD200303,CK, with the best cold resistance. We can know the relative electrical conductivity rate,the activities of SOD,the content of MDA,soluble sugar and free proline have the equivalent reliability as estimating on cold resistance of D.repens based on the proportion of their average accounting for the summation of fuzzy subordinate function are not significant.