| Sapindus mukorossi Gaertn.is a tall deciduous tree belonging to Sapindus of Sapindaceae,which has high utilization value in the fields of daily chemicals,biomedicine,bioenergy,landscape design and so on.In order to provide scientific basis for breeding Sapindus mukorossi provenances with drought resistance and shade tolerance by studying its growth and physiological characteristics.From June to August,2019,in the experimental forest farm of Hunan Academy of Forestry,drought stress and shading treatment of Sapindus mukorossi(2-year-old seedlings)were carried out.The duration of drought stress is 20 days,sampling and index determination are carried out every 5 days,and the duration of shading treatment is 60 days,sampling and index determination are carried out every 15 days.The measured indexes mainly include net increase height,biomass,leaf growth characteristics,chlorophyll content,MDA content,SOD activity,POD activity,CAT activity and so on.The drought resistance and shade tolerance of Sapindus mukorossi from three provenances were evaluated.The research results are as follows:(1)Drought stress has significant effects on the growth and physiological characteristics of Sapindus mukorossi.In terms of leaf growth characteristics,with the increase of stress duration,the leaf area and fresh weight of the three species of Sapindus mukorossi increased slightly,which were significantly different from those of normal cultivation,with a decrease of 12.8～25.6%and 18.1～50.2%,respectively.The relative water content of leaves gradually decreased,with a decrease of 11.3～19.6%compared with that of normal cultivation.In terms of chlorophyll content,with the increase of stress duration,chlorophyll a,chlorophyll b and total chlorophyll content of three kinds of Sapindus mukorossi decreased gradually,and there were significant new differences compared with normal cultivation,with decreases of 16.7～29.6%,7.7～10.4%and 15.1～25.1%,respectively.In terms of MDA and SP content,with the increase of stress duration,the MDA and SP content of three kinds of Sapindus mukorossi gradually increased by 25.4～46.1%and 6.9～18.3%respectively compared with normal cultivation.In terms of protective enzyme activity,with the increase of stress duration,the activities of SOD,POD and CAT of three kinds of Sapindus mukorossi increased in different degrees,which were significantly different from those of normal cultivation,with the increase rates being 23.8～53.2%,22.1～34.5%and 70.6～95.8%,respectively.(2)Shading stress has significant effects on the growth and physiological characteristics of Sapindus mukorossi.In terms of leaf growth characteristics,under moderate shading stress,the leaf area of the three species of Sapindus mukorossi increased slightly,while the leaf number and leaf water content decreased gradually,with significant differences compared with normal cultivation,with the decreases of 29.3～43.2%,34.8～40.0%and 11.7～20.1%respectively;Under severe shading stress,the leaf area of the three species of Sapindus mukorossi remained basically unchanged,while the leaf number and leaf water content gradually decreased,with significant differences compared with normal cultivation,with the decreases of 36.9～56.6%,51.9～61.5%and 19.0～29.4%,respectively.In terms of chlorophyll content,under moderate shading stress,chlorophyll a,chlorophyll b and total chlorophyll content of three kinds of Sapindus mukorossi gradually increased by 9.1～22.0%,5.1～28.0%and 8.1～20.6%respectively compared with normal cultivation;Under severe shading stress,the chlorophyll a,chlorophyll b and total chlorophyll content of CD and DA Sapindus mukorossi increased gradually,while the chlorophyll content of LL Sapindus mukorossi increased first and then decreased,which were-13.3～33.3%,-9.8～38.5%and-12.4～28.7%respectively compared with normal cultivation.In terms of MDA and SP content,under moderate shading stress,the MDA content of three kinds of Sapindus mukorossi gradually decreased or remained stable,while the SP content gradually increased,which were-9.4～0.5%and 17.6～33.1%respectively compared with normal cultivation;Under severe shading stress,the MDA content of three kinds of Sapindus mukorossi increased gradually,while the SP content increased first and then remained stable,with the increase rates being 6.8～18.9%and 10.4～23.7%respectively compared with normal cultivation.In terms of protective enzyme activities,the activities of SOD,POD and CAT of three kinds of Sapindus mukorossi were enhanced in different degrees under moderate and severe shading stress,among which the activities of the three enzymes under moderate shading stress were higher than those under severe shading stress,but they were all higher than those under normal cultivation,with the increase rates of 2.8～16.2%,22.9～34.9%,59.7～80.3%and 18.5～34.6%、11.1～24.3%、43.3～59.0%.(3)Eight indexes,such as leaf water content,MDA content and SOD activity,were selected.The resistance index of each index was determined by membership function method,and the weight of each index was determined by entropy weight method.The drought resistance and shade tolerance of three Sapindus mukorossi were evaluated.The results were LL(0.998)>DA(0.366)>CD(0.159),and The evaluation result of shade tolerance was DA(0.647)>CD(0.608)>LL(0.359).To sum up,drought or shade had a significant impact on the growth and physiological indexes of Sapindus mukorossi.The evaluation results of drought resistance and shade tolerance showed that LL Sapindus mukorossi had stronger drought resistance and DA Sapindus mukorossi had stronger shade tolerance. |
