| Cunninghamia lanceolata is widely cultivated in southern China.It is one of the fine afforestation and timber species,with the characteristics of fast growth and high output.The normal growth of Chinese fir is affected by many ecological factors,among which the water factor is an indispensable part of the life activities of Chinese fir,and it is an important medium for nutrient absorption and material transport of Chinese fir.With the global warming,the impact of drought on the main Chinese fir production areas in southern China severely restricts the yield and wood quality of Chinese fir plantations.However,the research on drought resistance of Chinese fir started late,especially the research on the screening and evaluation of specific drought-tolerant Chinese fir provenance and related hydraulic structural characteristics.Therefore,in-depth development of high-yield and high-quality drought-tolerant Chinese fir provenance and cultivation,study the hydraulic structure specificity of different drought-tolerant Chinese fir,is important for the drought-resistant fine Chinese fir directional cultivation and the yield per unit area of Chinese fir plantation.In this study,40 excellent Chinese fir clones collected from the fir engineering research center of the National Forestry and Prairie Bureau of Fujian Agriculture and Forestry University were used as materials,and the drought stress experiment was carried out under the natural conditions of potted water control method to carry out the growth and plant drought resistance-related physiology.The biochemical index was determined by the membership function method.The drought resistance of all tested Chinese fir clones was evaluated.The different drought-tolerant Chinese fir clones were screened.Finally,the hydraulic characteristics of main stems and lateral branches of different drought-tolerant Chinese fir clones were different.Analysis,the research results provide an important basis for the selection and directed cultivation of drought-tolerant Chinese fir.The main findings are as follows:(1)Under drought stress conditions,the relative water content of 40 different Chinese fir clones showed a decreased trend,and the decline range among different clones was different.Among them,the Chinese fir clones with the largest decrease in leaf relative water content were 26-5and 13-22,respectively,48.98% and 47.29%,and the smallest declines were 34-4 and 40-3,respectively,2.77%.And 3.10%.(2)Under drought stress conditions,the water retention capacity of40 Chinese fir clones decreased in different degrees,and the decline of different Chinese fir clones varied.The Chinese fir clones with strong water retention capacity were 15-31 and 15-1,showing strong drought resistance;the Chinese fir clones with fast water retention decreased were6-36 and 13-20,showing poor drought resistance.(3)Under drought stress conditions,the relative conductivity of the leaves of 40 Chinese fir clones increased,and the MDA content of leaves increased.Among them,the Chinese fir clone with the largest increase in conductivity was No.13-1,which was 7.8 times higher than that before stress.The clone with the smallest increase was 13-32,which was 2.3times higher than that before stress.The most uplifting MDA clones were No.67-34,which was 2.8 times higher than that before the stress.The clone with the smallest increase was 61-10,which was 1.1 times higher than that before the stress.(4)With the deepening of drought stress,the activities of antioxidant enzymes SOD,POD,PPO and CAT in 40 Chinese fir clones were different.Drought stress decreased the SOD activity of most Chinese fir clones,and the SOD activity of a few Chinese fir clones increased.The variation of SOD activity among different Chinese fir clones was different.The most uplifted Chinese fir clones were 13-10.No.,No.13-20 and No.46-38,respectively,were 8.44%,6.69% and5.14%,and the largest declines were 13-1,10-5 and 48-7,respectively,18.02%,10.68% And 9.38 %;drought stress decreased the POD activity of Chinese fir clones,and the POD activity of different Chinese fir clones decreased differently.The most declined Chinese fir clones were 48-7,15-1 and 40-3.60.00%,56.40% and 54.04%,respectively,the smallest declines of Chinese fir clones were 38-1,13-1 and 49-10 were 1.70%,1.96% and 3.54% respectively;drought stress made most of the Chinesefir The PPO activity of the clones decreased,and some of them showed an upward trend.The variation of PPO activity of different Chinese fir clones was different.The largest decline of Chinese fir clones were 40-3,6-36 and 13-20,respectively.72.78%,64.74% and 59.57%,the largest increase of Chinese fir clones is 64-6,69-2 No.3 and No.34-4 were81.63%,63.27% and 56.52% respectively;drought stress increased the CAT activity of most Chinese fir clones,and some of them showed a downward trend.The CAT activities of different Chinese fir clones varied differently.The most uplifted Chinese fir clones were 13-32,17-4,and6-23,98.93%,92.78%,and 82.05%,respectively.The largest decline of Chinese fir clones was 64-20,61-No.10 and No.34-4 were 78.28%,52.86% and 52.14% respectively.(5)The study found that drought stress significantly reduced the Fv/Fm values of 40 Chinese fir clones,and the variation range of different Chinese fir clones was different.The clones with smaller Fv/Fm values in drought stress were 13-10,70-17 and 5-7,respectively,9.39%,9.79% and 9.98%,and the clones with larger decline were 69-23,41-1and 13-22,27.20%,23.31% and 23.00% respectively.(6)This experiment tested 9 physiological and biochemical indexes closely related to plant drought resistance by comprehensive analysis of membership function method.According to the calculation,the drought resistance of each Chinese fir clone was 64-6>13-10>64-33>13-12>49-10>38-40>5-7>13-32>69-23>6-23>70-17>1-11>13-9>15-31>25-28>15-1>10-5>12-7>13-20>5-1>34-4>29-24>46-38>6-1>25-15>40-3>41-1>64-20>29-28>61-10>67-34>64-24>48-7>17-4>39-6>13-1>38-1>6-36>13-22>26-5.(7)In this study,the hydraulic structure characteristics of the main stems and lateral branches of 10 patience type and 10 susceptible Chinese fir clones were compared.The results showed that the water conductivity of the main stems of two drought-tolerant Chinese fir clones,the specific conductivity,leaf specific conductivity and Huber value are larger than the water conductivity,specific conductivity,leaf specific conductivity and Huber value of the lateral branches;the water conductivity of the main stem and lateral branches of the patience type Chinese fir clones,The specific conductivity,leaf specific conductivity and Huber value are larger than the water conductivity,specific conductivity,leaf specific conductivity and Huber value of the sensitive main stem and lateral branches of the Chinese fir,indicating that the main stem has high water delivery efficiency compared with the lateral branches,the water transport efficiency of the patience type Chinese fir clones is higher than that of the sensitive Chinese fir clones. |
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