Study On Adaptability Of Alternative Partial Root Zone Irrigation In Ginkgo Biloba

Alternative partial root-zone irrigation (APRI) is not only a biological water-savingtechnology, but also an important means of regulation of plant physiology and biochemistry. Inorder to explore the adaptability and the impact on secondary metabolites of APRI on the watermanagement strategy of Ginkgo, this research takes the3-year split root potted ginkgo as testmaterials, and the test takes two-factor three-level design: factor1is the water supply(Alternative partial root-zone subsurface irrigation, the fixed root zone subsurface irrigation andfull root zone subsurface irrigation); factor2is the amount of water supply (the three gradientsare normal water supply, mild drought and severe drought), doing research on the parameters ofthe growth and differentiation,physiology and Ecology, drought response, secondarymetabolites of ginkgo, combing with the analysis and discussion of SPAC system, such asIsohydric/Anisohydric behavior drought-resistant mechanism of water and the mechanism ofsecondary metabolites, the main conclusions are as follows:(1) Compared with conventional irrigation methods, APRI did not reduce the amount ofginkgo growth, but significantly improved the ginkgo root to shoot ratio, absorbing roots, rootactivity, and at the same time enhanced the ability of Ginkgo access to resources, and made theginkgo membrane less harm in mild drought stress. APRI stimulated the maximumcompensation effect, greatly improved plant water use efficiency and root to shoot ratio notaffecting the photosynthetic rate of plant water status, gave full play to the biologicalwater-saving potential of the plant itself. The ginkgo of partial root alternate water treatmentmaintained high chlorophyll content, Fv/FM, Yield, qP, effectively alleviated photo inhibitionprotect photosynthetic structure, but also eased the decomposition of photosynthetic pigments,and promoted to second growth of ginkgo.(2) The water use efficiency of Ginkgo and reactive oxygen species with the plasmamembrane injury index was significantly correlated. This showed that Ginkgo water useefficiency relative to its drought stress response and adaptation, with a lag, so blind pursuit toimprove the efficiency of water use would make the ginkgo by a serious reactive oxygen stress.One reason of APRI to improve ginkgo WUE was that APRI significantly reduced thetranspiration rate and stomata conductance, thus improved the efficiency of water use with a notsignificantly reduction in the photosynthetic rate; the second was that APRI increased the roothydraulic conductivity, and enhanced root absorption capacity. (3) Under different water conditions, ABA and ginkgo water status regulation, osmoticregulation and reactive oxygen metabolism were closely related. The accumulation of ABAplayed an important role not only in the link between ginkgo and environmental factors, butalso in the Ginkgo leaf water status and related drought metabolic regulation mechanism.(4) Ginkgo stomatal conductance and leaf water status and osmotic substances related tohigh; the indicators of leaf water potential and water status, stress signal, osmotic adjustmentand resource indicators closely related. This study found that ginkgo was isohydric plants, andwater potential in line with the stomatal regulation, leaf water potential impacted on thesensitivity of stomatal conductance to ABA, Ginkgo stomatal regulation was the result of therole of chemical and hydraulic signals. Under water deficit the ginkgo through the stomata andwater potential adjustment in the SPAC system would try to keep the body water balance.(5) Ginkgo improved the drought adaptability mainly in two ways:the one hand, byreducing the stomatal conductance to reduce water loss, improving the efficiency of water use,to avoid excessive transpiration caused by the catheter air lock and excessive reduction of thewater potential, at the same time, to increase the absorption of roots and root activity to absorbwater as much as possible; on the other hand, the increase in the accumulation of osmolytes,improving the ability of active oxygen scavenging, the synthesis of biologically activesubstances to protect the structure and function of nucleic acids, proteins and membrane lipids.The series of reactions of the Ginkgo aimed to maintain body water status within the normalrange to ensure normal physiological activity.(6) The APRI and mild drought stress could contribute to the accumulation of proline andpolyamines, which showed that under the condition that APRI and soil water content of55%ofthe maximum water holding capacity, the ginkgo most resistant. The accumulation of prolineand polyamines in Ginkgo biloba had a feedback mechanism which could maintain the dynamicequilibrium at a level, depending on the stress situation. Ginkgo biloba proline, endogenoushormones and active oxygen scavenging in plant stress in osmotic adjustment was closelyrelated showed that proline extensively involved in the process of the plants in the water deficitresponse and adaptability. Different types and forms of polyamines in plant stress adaptationrelated to the polyamine storage, ion balance, osmotic adjustment, protection of biologicalmacromolecules based. Ginkgo leaf proline content and P5CS activity was a significant linearrelationship. arginine pathway played a key role in polyamine biosynthesis, and this studyfound that there may be a competition to ornithine in polyamine, and proline biosyntheticpathway under drought stress.(7) APRI and mild drought stress conducive to the accumulation of Ginkgo bilobaflavonoids and terpene lactones, and the improving of phenylalanine ammonia-lyase andchalcone isomerase activities of key enzymes. This study found that the synthesis andaccumulation of ginkgo flavonoid, reactive oxygen stress and endogenous hormones closelyrelated,and ginkgo flavonoids may play directly or indirectly in cell growth and differentiationregulation and anti-aging, and the conservation of biological macromolecules. Ginkgolides in ginkgo body widely involved in plant growth, differentiation and stress signal transduction andstress adaptation process, but ginkgolides and ginkgo growth,differentiation regulation relatedmore closely. Ginkgo flavonoids, the terpene lactones secondary metabolite synthesismechanism were the comprehensive reflection of the hypothesis of oxidation stress effects,growth/differentiation balance and resource availability.APRI not only could improve the ability to adaptability and water use efficiency of theginkgo, but also was a simple, safe and reliable method improving the content of flavonoids,terpene lactone in ginkgo, without reducing the biomass.