| Camellia oleifera is an important woody edible oil species in China,which is mainly planted in hilly areas in south of China.The temperature is usually higher with little rainfall in these areas during July to October,drought always happen and seriously affect the growth and development of C.oleifera.Nitrogen,as an essential element for plant growth,has a certain effect on the growth physiology and drought resistance of C.oleifera.However,there are few studies on the effects of drought and nitrogen application on foliage growth and physiology of C.oleifera,and the response of foliage growth and physiology to drought and nitrogen application remains unclear.Therefore,this study takes 2-year-old C.oleifera‘Changlin 53’ grafted saplings as the research object,by setting the control(CK),drought(D),nitrogen addition(N),Drought plus nitrogen addition(DN)potted control experiment,the study of drought and nitrogen fertilizer on foliage morphology,physiological and differential of sapling growth,biomass accumulation and allocation,and the effects of nonstructural carbohydrates(NSC)and distribution,To investigate the response of C.oleifera growth and physiology to drought and nitrogen addition in order to provide theoretical basis for scientific management of C.oleifera under drought.The main results are as follows:(1)Both drought and nitrogen addition had significant effects on the growth of young C.oleifera trees.The biomass of fresh foliage and dry foliage of young C.oleifera trees decreased by 18.8% and 20.9% under D treatment.The interaction between drought and nitrogen application had no significant effect on the growth of young C.oleifera trees,but the total foliage surface area,total length,total width,total foliage number,biomass and allocation ratio of young C.oleifera trees under DN treatment were higher than those under D treatment.(2)Drought significantly reduced the chlorophyll content of young C.oleifera foliage.Nitrogen addition significantly increased chlorophyll content in young foliage of C.oleifera.The contents and total amount of chlorophyll pigments in DN treatment were higher than those in D treatment.(3)Drought and nitrogen addition significantly increased the activities of superoxide dismutase,peroxidase and catalase in foliage of young C.oleifera trees.The interaction of drought plus nitrogen addition had no significant effect on the antioxidant enzyme activities of young foliage of C.oleifera,but the activities were higher than those of D treatment.The malondialdehyde content in foliage of young C.oleifera was increased by 20.2% under D treatment,and the malondialdehyde content under nitrogen addition was lower than that under D treatment.(4)Drought significantly increased soluble protein content and proline content,and soluble sugar content of young C.oleifera foliage.Nitrogen addition significantly increased soluble protein content and proline content.The interaction of drought plus nitrogen addition significantly increased soluble protein content and proline content by 2.63 times.(5)Drought significantly reduced the total starch content in foliage and the proportion of total NSC in foliage,and significantly increased the total NSC content in stems.Nitrogen addition significantly increased total starch content in foliage,total starch ratio in shoot and total NSC content in stem.Under drought condition,nitrogen addition reduced the proportion of NSC in foliage.In conclusion,drought and nitrogen addition have certain effects on the growth and leaf morphology of young C.oleifera trees.C.oleifera saplings responded to drought by increasing antioxidant enzyme activity,osmotic regulation substance content and regulating NSC allocation.Nitrogen was applied to regulate the activity of antioxidant enzymes and osmotic regulation to promote the growth and development of young C.oleifera trees.Nitrogen application can alleviate the effect of drought on young C.oleifera trees to a certain extent. |
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