Individual Size Dependence With Twig-leaf Traits And Photosynthesis Of Lavandula Angustifolia In The National Wetland Park On Goldwater Lake,Gansu

Light is the most important environmental factor that affects plant photosynthesis and its survival and expansion.Plants adapt and respond to the heterogeneous light environment by adjusting the external morphology and internal physiological characteristics of their organs.The characteristics of branches and leaves are the result of the long-term interaction between plant genetic genes and natural environment,which can reflect the survival adaptability of plants and the way of resource utilization.In the process of plant growth and reproduction,due to the differences in life cycle length and individual size,the light intensity and light quality of the environment in which the plant is located are different,which have a significant impact on the morphological and physiological characteristics of the leaves.Many scholars have analyzed the formation and physiological process of branches and leaves,leaf photosynthesis and chlorophyll fluorescence characteristics,etc.However,the combination of leaves and branches with photofluorescence still leaves much to be desired.The study area in this paper is the jinshui lake national wetland park in jinchang,gansu province,Lavandula angustifolia was divided into three size grades?grade I:d 60 cm,grade II:60 cm<d 90 cm and grade III:d>90 cm?according to the cube root of plant volume.Using one-way anova analysis,correlation and RDA two dimensional sorting,based on the theories of the relationship between the growth of plant branches and leaves and photosynthesis,the relationship between leaf and branch traits and individual size,leaf and branch traits and photosynthetic characteristics,as well as leaf and branch traits and chlorophyll fluorescence characteristics of Lavandula angustifolia were analyzed,the purpose of this paper is to systematically expound the strategies of plant resource allocation and light environment response,so as to enhance the understanding of plant photosynthetic yield distribution and environmental adaptability.The results show that:?1?There were significant differences in branch length,crown width,branch angle and number of one or two and perennial branchlets between different grades of Lavandula angustifolia,the difference of branch cross-sectional area is not significant.As the size of Lavandula angustifolia increased from grade to grade,the length of crown branches,the cross-sectional area of branches and the number of twigs in one or two years increased gradually,while the branch angle decreased gradually.?2?There were significant differences among the leaf characters of Lavandula angustifolia of different sizes and grades.As the size of Lavandula angustifolia increased from grade?to grade?,the number of LA and leaves of Lavandula angustifolia increased gradually,and the thickness and inclination of leaves decreased gradually,This indicated that the large individual Lavandula angustifolia had a few large and thin leaves extending horizontally,while the small individual Lavandula angustifolia had many small and thick leaves arranged at a certain angle.?3?With the increase of size and grade Pn,Tr,stomatal conductance?Gs?and intercellular CO₂ concentration?Ci?all showed a decreasing trend,the results showed that the living environment of large individual Lavandula angustifolia was relatively humid with low evaporation and Pn.The living environment of small individual Lavandula angustifolia is relatively dry,with large moisture evaporation and high Pn.?4?There was a significant negative correlation between LA and Pn in the three grades?P<0.01?,and a significant negative correlation between LA and Tr?P<0.01?,there was a significant positive correlation between the leaf thickness and Pn of grade I and grade II Lavandula angustifolia,while the positive correlation between the leaf thickness and Pn of grade III Lavandula angustifolia was not significant,and there was a significant positive correlation between the leaf thickness and Tr of grade I Lavandula angustifolia and grade II Lavandula angustifolia,while the positive correlation between the leaf thickness and Tr of grade III Lavandula angustifolia was not significant,The results showed that in order to improve the efficiency of photosynthesis and transpiration,large individual Lavandula angustifolia chose to increase the leaf area,while small individual Lavandula angustifolia chose to increase the leaf thickness.?5?There was a significant negative correlation between branch length and Tr of grade I to grade III Lavandula angustifolia?P<0.01?,indicating that Tr decreased with the increase of individual size and grade.There was a significant negative correlation between branch cross-sectional area of grade I to grade III Lavandula angustifolia and Tr?P<0.01?,indicating that Tr decreased with the increase of individual size and grade.?6?There were significant differences in actual photosynthetic efficiency?Y?II??,non-photochemical quenching coefficient?NPQ?and apparent electron transfer efficiency?ETR?between different grades?p<0.05?,Y?II?and ETR increased gradually from grade I to grade III Lavandula angustifolia,while NPQ decreased gradually from grade I to grade III Lavandula angustifolia.There was no difference in non-regulatory energy dissipation quantum yield?Y?NO??between the three grades of Lavandula angustifolia,there was no difference in regulatory energy quantum yield?Y?NPQ??and photochemical quenching coefficient?Qp?between grade II and grade III Lavandula angustifolia,but there was a significant difference between grade I Lavandula angustifolia,and the the Y?NPQ?of grade II and III Lavandula angustifolia was less than that of grade I Lavandula angustifolia,however the Qp of grade II and III Lavandula angustifolia was more than that of grade I Lavandula angustifolia.Different individual sizes of plants can provide a differentiated environment for the growth of branches and leaves.Large individuals tend to suffer from severe shade,while small individuals are threatened by light.A synergistic relationship will be formed between the growth of branches and leaves and the environment,and it will affect the absorption and utilization of light energy by leaves.By adjusting these changes,plants can choose the construction mode of functional traits beneficial to their survival and reproduction,which is also the embodiment of the self-regulation mechanism of plants under the promotion of individual size...