Effects Of Different Fertilization Treatments On The Growth And Leaf Physiology Of ’Qi-Nan’ Agarwood Seedlings From Aquilaria Sinensis

’Qi-Nan’ agarwood,originating from Aquilaria sinensis(Lour.)Glig,is a kind of agarwood with fast formation,good quality and excellent performance,with high application value and economic value.In this study,pot trials and field trials were set up using grafted seedlings of ’Qi-Nan’ agarwood as test material,from the potted seedling cultivation stage to the young forest nurturing stage of transplanting to the field.In the pot experiment,seven fertiliser gradients ranging from 0 g/plant to 23 g/plant were applied at different fertiliser levels.In the field experiment,four fertiliser types and four fertiliser gradients were set up in an orthogonal Latin square design to explore the seasonal changes in the growth and physiological characteristics of ’QiNan’ under different fertiliser types and fertiliser levels.The main results are as follows:(1)Pot experiment results showed that: within a certain range,with the increase of the application amount of organic-inorganic complex fertilizer,the growth amount and physiological activity of ’Qi-Nan’ agarwood had increased effect,but this effect formed a turning trend when the application amount was too high,some seedlings appeared "burning" or even dying.At 7g/plant,the seedling height,diameter and chlorophyll content increased more;at 11g/plant,the soluble protein content and POD activity increased more;and at 19-23g/plant,the soluble sugar content and SOD activity increased more.Membership function analysis showed that organic-inorganic complex fertilizer had significant effects on the growth of ’Qi-Nan’ agarwood,and the optimal level of single application of organic-inorganic complex fertilizer was about 7-11g/ plant.(2)The base fertilizer test results showed that the single application of organic fertilizer as the base fertilizer promoted the growth of the height and ground diameter of ‘Qi-Nan’ agarwood seedlings.The main factors affecting seedling height and ground diameter of ‘Qi-Nan’ were free proline,chlorophyll,total nitrogen and total potassium.The membership function analysis showed that the growth effect of ‘Qi-Nan’ agarwood seedlings was the best under the treatment of vermicompost,followed by microbial organic manure and sheep manure.(3)The topdressing test results in the field test showed that the morphological index of ‘Qi-Nan’ agarwood seedling under the topdressing condition was better than that of base fertilizer alone,but too high topdressing amount would also reduce the growth of the seedling.Among them,the fertilization treatment of vermicompost(base fertilizer)+ 150 g organicinorganic complex fertilizer(top fertilizer)was more conducive to the growth of seedling height,ground diameter and chlorophyll content,and the fertilization treatment of microbial organic fertilizer(base fertilizer)+ 300 g organic-inorganic complex fertilizer(top fertilizer)was more conducive to the growth of soluble protein,soluble sugar content and SOD activity.Sheep manure(base fertilizer)+ 300 g organic-inorganic complex fertilizer(topdressing)was more conducive to the increase of POD activity.Membership function analysis showed that the optimal formula combination was microbial organic fertilizer or vermicompost(base fertilizer)+ 150 g organic inorganic compound fertilizer(topdressing).In conclusion,considering the economy of seedling growth and fertilization,the most suitable fertilization mode for ‘Qi-Nan’ agarwood is: pot planting with organic-inorganic complex fertilizer of 7g/ plant;After transplanting in the field,microbial organic fertilizer or vermicompost was used as base fertilizer,and 150 g organic-inorganic complex fertilizer was used as topdressing fertilizer.Under this fertilization mode,the growth and physiological state of ‘Qi-Nan’ agarwood seedlings were the best.