Physiological Response Of Ornamental Gardenia To Different Shading Treatments

Gardenia jasminoides belongs to the genus Gardenia in the Rubiaceae family.It is suitable for warm and humid environment,and can withstand cold and shade.In order to compare and analyze the suitable light intensity environment which is beneficial to the growth and development of Gardenia jasminoides under the forest,we hope to provide reference for the rational utilization of different Gardenia jasminoides varieties and the corresponding high efficiency and quality cultivation.In this study,Gardenia jasminoides var.grandiflora,Gardenia jasminoides var.radicans and Gardenia jasminoides var.variegata were treated with different gradients,compared with natural light and natural shading treatments.Analyzed the morphological growth,nutrient elements,photosynthetic characteristics and protective enzyme activities of leaf,and the following main research results were obtained:Ⅰ)Under 60% shading rate,Gardenia jasminoides var.grandiflora and Gardenia jasminoides var.radicans showed excellent performance in plant height,crown width,stem diameter,flowering number and root length.Under natural light,the stomatal density of gardenia microphylla was higher.Gardenia jasminoides var.variegata grows well in natural light and natural shade.The palisade tissue thickness of Gardenia jasminoides var.radicans and Gardenia jasminoides var.variegata Mosaic decreased gradually with the increase of shading intensity,and the difference was significant among different treatments.Shading had little effect on the biomass allocation of Gardenia jasminoides var.grandiflora,but under 90% shading rate,the biomass was more allocated to leaves and stems,and the R/C was smaller.Under natural light and 60%,70% shading rate,the biomass will be more allocated to the root,the R/C is larger.The biomass allocation of Gardenia jasminoides var.radicans and Gardenia jasminoides var.variegata was significantly affected by light intensity.Under excessive shading,the biomass would be more allocated to leaves.Under moderate shading,more biomass will be allocated to the stem.Under natural light,more of the biomass is allocated to the root,which has a larger R/C.However,Gardenia jasminoides var.variegata accumulated the most biomass under natural shading.Ⅱ)The three Gardenia jasminoides had higher nitrogen content under natural shading.Under 90% shading rate,Gardenia jasminoides var.grandiflora and Gardenia jasminoides var.radicans microphylla accumulated more N and K,while P content was higher under moderate shading.The N content of Gardenia jasminoides var.variegatawas higher under excessive shading,the P content was higher under natural light,and the K content was lower under 60% shading rate.The contents of N and K in the organs of the three Gardenia jasminoides were in the order of leaf,root and stem,the contents of P in the organs of the Gardenia jasminoides var.variegata were in the order of leaf,stem and root,and the contents of P in the organs of the other two Gardenia jasminoides were in the order of root,stem and leaf,but there was little difference in the contents.Ⅲ)Under natural shading and 60% shading rate,APX and SOD activities of Gardenia jasminoides var.grandiflora and Gardenia jasminoides var.radicans were significantly enhanced,while POD activity was the highest under natural light,and MDA activity reached the maximum under 90% shading rate.The soluble protein content in Gardenia jasminoides var.Grandiflora decreased with the decrease of light intensity,while the soluble sugar content increased first and then decreased with the decrease of light intensity.The soluble protein and soluble sugar contents of Gardenia jasminoides var.radicans also increased first and then decreased with the decrease of light intensity.Ⅳ)The results showed that with the increase of shading degree,the content of chlorophyll also increased gradually,and the net photosynthetic rate,transpiration rate,light compensation point,light saturation point,transpiration rate and other indexes of Gardenia jasminoides var.radicans and Gardenia jasminoides var.variegata decreased gradually,while stomatal conductance and water instantaneous utilization rate reached the maximum under 60% shading rate.The maximum net photosynthetic rate and apparent quantum efficiency of Gardenia jasminoides var.grandiflora were significantly increased under shading treatment.The chlorophyll fluorescence parameters were also different with the increase of shading intensity.Fo and Fm of the three Gardenia jasminoides increased gradually,while Qp and Qn decreased gradually,and there were significant differences among different treatments.The light energy conversion efficiency of the three Gardenia jasminoides was basically between0.75 and 0.85。In conclusion,60% shading rate is beneficial to the morphological growth,antioxidant enzyme activity,soluble sugar and soluble protein content of gardenia grandis and gardenia microphyllum.It is beneficial to the growth of gardenia jasminoides under natural light.90% shading rate was beneficial to the morphological growth of three gardenia leaves.Different light intensity will have different effects on the contents and distribution of N,P and K of the three Gardenia jasminoides.The regularfound in this study can be applied to the actual curing process.The three Gardenia jasminoides had certain plasticity in response to light intensity,moderate shading was beneficial to the improvement of photosynthetic efficiency and Light energy conversion efficiency,among which Gardenia jasminoides var.grandiflora was the most obvious.