Studies On The Seedling Physiological-biochemical Characteristics In Different Camptotheca Acuminata Provenance Under Drought Stress

Drought stress, the most severe abiotic stress detrimental to plant growth and development, not only restricts plant growth and yield, but also can cause the spatial and temporal change of the vegetation structure and function. In order to solve problems such as the frequent water shortages in non-arid areas and vegetation restoration in semi-arid and semi-humid region, it is of great importance to study and explore the drought-resistance mechanism and select the drought-resistant and adaptable species. With the aim of laying a solid foundation for breeding drought-resistant Camptotheca acuminata and offering scientific basis for its promotion and application, one-year-old seedlings from 8 different provenances were studied on the effects of physiological-biochemical characteristics on drought stress. Through the determination and analysis of morphological and physiochemical indexes in the experiments, the main results are as follows:(1) The seeding height increment, ground diameter increment and total biomass of all seedlings from different Camptotheca acuminata provenances decreased under drought stress, while their root/shoot ratio increased with the decreasing soil moisture content. These 4 indexes had significant differences amongst provenances and soil moisture levels (p<0.05).(2) Under the drought stress, the whole trend of SOD, POD, and MDA of seedlings increased, but the tendency and extend of these three indexes were not very consistent in different provenances. Variance analysis indicated that SOD, POD, and MDA had significant difference among each provenance and each level of soil moisture (P<0.05).(3)Under drought stress, indexes such as RWC, Chl, Car, Fv/Fm, Fv'/Fm', Pn, Gs and Tr all decreased while WUE and RWC significantly increased among each provenance and each level of soil moisture (P<0.05). Ci was not very consistent among each provenance and different treatments.(4)With decreasing of soil moisture, CPT content of leaves increased first and then decreased broadly. HS provenance had the highest CPT content, which was 1.23 times as high as the average under the light drought stress, while under the severe drought stress GY provenance was the highest, 1.53 times as high as the average and 3.03 times as high as the lowest (NJ provenance) respectively.(5)According to the comprehensive evaluation of drought-resistance for 8 provenances, the results showed that: under light drought stress the range of drought resistance from strong to weak could be: KM> CX> GY> LQ> SY> NJ> HS> NC, but under severe drought stress the range could be: GY> CX> NJ> KM> NC> LQ> SY> HS.(6) Considering all the above, here are some suggestions: Provenances GY, CX and NJ are good options in arid regions, but provenances KM, CX and GY are good option in semi-arid and semi-humid regions; With the aim of having higher levels of CPT in leaves, the water stress for the seedings of Camptotheca acuminata can be a consideration in the cultural management.