Study On Water Physiology And Intergration Characteristics Of Phyllostachys Edulis Seedling

Phyllostachys edulis?P.edulis?is an important economic and ecological bamboo species in China and a typical clonal plant..In the context of global climate change,extreme climate disasters occur frequently,combined with factors such as artificial logging,topography,soil,and spatial and temporal distribution patterns of precipitation.During the growth process of P.edulis,it is often affected by seasonal drought or heterogeneity of soil moisture.Water has become one of the important factors affecting the cultivation of high quality and high yield of P.edulis.Under this background,mastering the water physiological and integration characteristics of P.edulis can provide a theoretical basis for efficient water use and scientific fertilization in P.edulis cultivation.In this study,the P.edulis sprouting seedlings are used as the test materials.The relationship between water and P.edulis photosynthesis yield,efficiency and productivity was discussed by establishing a regression model.Propose the high yield and high efficiency water content range and drought stress threshold of P.edulis;Using laser confocal microscopy and non-invasive micro-technologyto study the Ca²⁺response characteristics and spatial distribution of P.edulis,further determine the role of Ca²⁺signal in ABA and H₂O₂signaling networks under drought stress;Combined with ¹⁵N isotope tracing techniques,the physiological integration phenomenon of P.edulis growth and cultivation was explored.The water physiological integration characteristics of P.edulis were analyzed by heterogeneous water stress treatment,and the beneficial effects of rhizome on the whole plant were determined.The main findings are as follows:1.The photosynthesis and water physiological characteristics of P.edulis sprouting seedlings showed obvious regular changes under different soil water contents.It can be used as an important basis for the classification of soil water productivity and the division of water stress threshold based on“production”and“effect”of P.edulis.The soil relative water content?RWC?of high-yield and high-efficiency water of P.edulis ranged from 44.69%to 94.32%.When the soil RWC between 34.25%and 44.69%is the middle-class high-efficiency water of P.edulis.When RWC greater than 94.32%is the high-yield medium-efficiency water,and when the RWC less than 17.41%is the non-productive water;The water stress of P.edulis are 17.41%?RWC?44.69%and RWC?94.32%,and the RWC was more than 17.41%,which was the endangered death threshold of three-year-old P.edulis sprouting seedlings.2.Ca²⁺plays an important role in the response to drought stress in P.edulis sprouting seedlings,mainly reflected in the Ca²⁺flux rate and Ca²⁺spatial and temporal distribution.When P.edulis sprouting seedlings are subjected to drought stress,the different parts of root tip have different Ca²⁺absorption capacities.The ability to absorb Ca²⁺are as follows:Pileorhiza>Meristem region>Elongation region>Mature region;And the absorption intensity of Ca²⁺signal is related to the degree of drought stress of P.edulis sprouting seedlings;Extracellular Ca²⁺can enter the cytoplasm through the calcium channel of P.edulis cells;Exogenous application of ABA can promote the absorption capacity of Ca²⁺in the pileorhiza of P.edulis.That is,ABA may have the role of activating plasma membrane calcium channels,and can induce the burst of reactive oxygen species H₂O₂in leaf guard cells.On the time and space distribution of Ca²⁺,with the increase of drought stress time,the concentration of Ca²⁺in almost all living cell cytoplasm increased except for the tethered cells in P.edulis leaves.Among them,the concentration of Ca²⁺in long cells increased significantly.3.Rhizome is the“hub”for the integration of material resources of different clones of P.edulis.The ¹⁵N mark integration effect is manifested as a process of transporting ¹⁵N labeled bamboo through rhizome to each cloned ramets.The P.edulis sprouting seedlings can cause nitrogen transfer between cloned plants through rhizome.Regardless of the ¹⁵N-labeled or cloned ramets,the ¹⁵N uptake of the labeled bamboo is the largest,and the absorption of ¹⁵N in each organ of the distantly labeled bamboo is small.This is the result of physiological integration of P.edulis.The ¹⁵N isotope tracer found that the ¹⁵N partition rate in bamboo leaves is 33.07%.In turn,it is stalk?26.25%?,branch?22.83%?,rhizome?13.91%?,root?3.93%?.The ¹⁵N utilization and absorption in various organs of P.edulis showed large to small are as follows:leaf,stalk,branch,rhizome,root.The strong photosynthetic function and developmental stage of the leaves lead to higher ¹⁵N utilization and absorption;Ndff showed:branch?0.45%?,stalk?0.40%?,leaf?0.38%?,root?0.26%?,and rhizome?0.18%?.4.In a heterogeneous water environment,the P.edulis clonal ramets can cause a series of physiological"cascade"reactions by rhizome.P.edulis initiates a series of physiological cascades through physiological integration in a heterogeneous water environment.Under drought stress,the content difference of endogenous hormones jasmonic acid?JA?,abscisic acid?ABA?,auxin?IAA?and osmotic adjustment substances Proline?Pro?and betaine?Bet?in the clonal ramets of the connected rhizome?physiological integration?was less than that of the disconnected rhizome treatment,preventing the physiological integration;At the same time,the difference of antioxidant enzyme activities such as superoxide dismutase antioxidant enzyme activities?SOD?,peroxidase?POD?and catalase?CAT?between allowing integration of the clonal ramets is also smaller than that of disconnected rhizome treatment.The Ca²⁺absorption capacity of pileorhiza,leaf and rhizome cut surface of P.edulis was also different under physiological integration.Physiological“cascade”responses indicate physiological integration characteristics in clonal ramets of P.edulis.The physiological characteristics of the clonal clones are more conducive to improving the drought tolerance of the whole clonal system,which relieves the environmental pressure of the sink clone ramet and realizes the sharing of resources and nutrients.In-depth study on the physiological and integrated characteristics of water and nutrients under the water physiology and heterogeneous water conditions of P.edulis,providing theoretical basis for the technical measures and practice for reference of high-efficiency cultivation of P.edulis,such as water stress diagnosis,efficient water use,scientific fertilization and water and fertilizer coupling precision management.