Effects Of Shading And High Temperature Treatments On The Morphology And Physiology Of Three Aromatic Plants

In this study,through the determination of Cymbopogon citratus,Melissa officinalis,and Rosmarinus officinalis ‘Severn Sea’,three aromatic plants in CK(full light treatment),T1(50 % shading treatment),T2(70 % shading treatment)and T3(85 % shading treatment)four different shading treatment and high temperature(35 °C)under the condition of morphological and physiological changes,to explore the influence of light and high temperature on the growth morphology and physiological and biochemical characteristics of three aromatic plants.The principal component analysis and membership function analysis were used to comprehensively evaluate the adaptability of the three plants,which could provide a theoretical basis for the popularization and application of vanilla plants in gardens in the future.The main results are as follows:(1)With the increase of shading intensity,the plant height,leaf length of C.citratus,M.officinalis and ‘Severn Sea’ increase,but leaf width decreased;the nutrient content of N,P and K in the leaves of C.citratus,M.officinalis and ‘Severn Sea’ were higher than CK.The total biomass of the three plants under T1 and T2 were higher than CK,while the total biomass of T3 decreased.Through observation and analysis,C.citratus grows best under T2,M.officinalis grew better under T1 and T2.‘Severn Sea’ grew slowly under each treatment,and there was no significant difference among the treatments.(2)With the increase of shading intensity,the content of chlorophyll a,chlorophyll b and total chlorophyll of the three plants increased;SOD activity and soluble protein content increased,while MDA content,POD activity and soluble sugar content decreased.The results showed that T1 and T2 treatments promoted plant growth,CK and T3 treatments inhibited plant growth.(3)Under high temperature ttreaments,the content of chlorophyll a,chlorophyll b,total chlorophyll and carotenoid of C.citratus showed a downward trend,while M.officinalis showed an upward change,and that of ‘Severn Sea’ increased first and then decreased.The relative electrical conductivity,MDA content,soluble sugar and soluble protein content of C.citratus and M.officinalis increased,and SOD activity decreased.The relative electrical conductivity,MDA content and SOD activity of ‘Severn Sea’ changed little.The results showed that the heat resistance of C.citratus was worse under high temperature treatment.M.officinalis and ‘Severn Sea’ have better heat resistance.Comprehensive analysis,the negative tolerance of the three fragrant plants is C.citratus > M.officinalis > ‘Severn Sea’;the high temperature tolerance of C.citratus is weaker than that of M.officinalis and‘Severn Sea’.