Effect Of Shading On Photosynthetic Physiological Characteristics Of Six Lotus Flowers And Evaluation Of Shade Tolerance

In recent years,the development of ornamental flower industry has gradually grown,lotus is one of the ornamental flowers commonly used in plant landscaping in the past,and it is also one of the national essences of China,in order to promote the diversification and industrialization of lotus germplasm resources;To enhance the ecological benefits of ornamental lotus flowers,increase economic benefits,develop flower composite business model,tourism development,meet the needs of the home horticultural market,etc.,it has important scientific and practical production significance to carry out resistance research on ornamental lotuses,and the research on the shade tolerance of ornamental lotuses is worth exploring and practicing.In this paper,three processing levels are set by shading net（shading rate:T1:18%～25%;T2:45%～55%;T3:65%～75%）,and control group T0,6 kinds of ornamental lotus flowers’pink Lingxiao’,’Xinghong’,’Hongmudan’,’Dahongyun’,’Daziyu’,’Tongshuai’were selected as the experimental materials for research,after 45d shading treatment,the morphological indicators,photosynthetic parameters,chlorophyll fluorescence parameters,physiological and biochemical indicators of 6 ornamental lotus flowers were determined.The main conclusions are as follows:1.The plant height,flowering period and leaf area of 6 ornamental lotus flowers were changed after shading treatment.Compared with the control,the plant height and leaf area of the six ornamental lotus flowers under different shading treatments increased.The’Tongshuai’has the largest growth in full light,which is 27.7cm,indicating that it needs to be light;Under the 45%-55%shading treatment,the leaf area and plant height of’Xinghong’increased the most,which increased by 140%and 57.10%respectively compared with the control,and under the 65%-75%shading treatment,the plant height growth of’Daziyu’was the largest,which was 50.5cm.The leaf area of’Pink Lingxiao’increased the most,by 132.96%compared with the control;The time delay and flowering amount of 6 ornamental lotus flowers entering the budding stage under different shading treatments is reduced;And the budding period is delayed by 20 to 29 days under 45%to 55%shading treatment;Under the treatment of 65%to 75%shade,some varieties can flower such as’Xinghong’and’Daziyu’.2.The photosynthetic parameters and fluorescence parameters of 2.6 ornamental lotus flowers were changed after shading treatment.With the increase of shading rate,the maximum net photosynthetic rate(P_nmax),light saturation point（LCP）,light compensation point（LSP）,and dark respiration rate（R_d）of the six ornamental lotus flowers showed a decreasing trend,and the changes in P_nmax and R_d were significant.Among them,’Xinghong’has a higher light saturation point and a lower light compensation point,and under moderate and severe shade,the use of light is significantly reduced by reducing R_d,indicating that its shade tolerance is strong.The’Tongshuai’has the largest AQY decline under T2 and T3treatment,and the light compensation point is higher,indicating that the lack of light of the’Tongshuai’is not conducive to his growth.With the increase of shading rate,Fv/Fm and q P decreased in the PSII system of 6 ornamental lotus leaves.The difference in F₀changes is not significant,NPQ is reduced first and then increased or decreased first and then decreased,ETR is increased first and then decreased,of which’Tongshuai’has the largest decline under T2 and T3 treatment,which is the most damaged by weak light,and the most intolerant;Under the three shade treatments,the variations of Fv/Fm,q P and NPQ of’Xinghong’were not obvious,indicating that the shade had less effect on its PSII system and strong shade tolerance.3.The physiological characteristics of 3.6 kinds of ornamental lotus flowers changed significantly after shading treatment.The stomata density of six kinds of ornamental lotus flowers decreased under different shading treatments;With the increase of shading rate,the contents of chlorophyll a,chlorophyll b and total chlorophyll continued to increase and the content of chlorophyll a/b decreased;Gradual decrease in soluble sugar content;MDA content decreased first and then increased;POD and SOD activity rises first and then falls.4.The comprehensive evaluation of the six ornamental lotus flowers by the membership function method shows that the order of the negative tolerance of the six ornamental lotuses is from strong to weak:lotus cultivar’Xinghong’>’pink Lingxiao’>’Hongmudan’>’Daziyu’>’Dahongyun’>’Tongshuai’,The more significant correlation indicators with the negative tolerance were Pnmax,LCP,leaf area,SOD activity,flowering number,and non-photochemical quenching coefficient.In summary:This paper found that 6 kinds of ornamental lotus flowers can grow and flower in an environment with a shading degree of 45%to 55%,and some varieties can grow and flower in an environment of 65%to 75%,which in turn shows that the adaptation range of ornamental lotus flowers to light is still relatively wide,and some varieties can be cultivated in a complex operation under thinning forests,and it is possible to develop a new flower tourism model.