Modeling The Geographic Distribution Of Platycrater Arguta And The Effect Of Drought Stress On It

Platycrater arguta Sieb.et Zucc.is one kind of deciduous shrub belonging to the family Hydrangeaceae,a rare and endangered plant of the Third Age,and a national secondary protected plant.This paper uses the DIVA-GIS software and its integrated BIOCLIM and DOMAIN models to predict the current and future potential distribution areas of the P.arguta.The accuracy of the model is tested,and the climatic factors that dominate the distribution are used as principal component analysis.In order to verify whether P.arguta are sensitive to changes in moisture,oneyear-old P.arguta seedlings were used as materials,and four water gradients,75%-80%(control),60%-65%(mild drought),were set with potted water control tests,45%-50%(moderate drought),30%-35%(severe drought),its growth indicators,physiological and biochemical parameters,photosynthetic gas exchange parameters,and chlorophyll fluorescence parameters were determined.The main results of the paper are as follows:(1)The potential distribution areas of P.arguta in the present are mainly concentrated in the border areas of Fujian,Zhejiang,Anhui,Fujian,Zhejiang,Jiangxi,Anhui,Zhejiang,Yandang Mountains,the junction of Hunan and Hunan,and the junction of Hunan and Guangxi,and the northern part of Kyushu and Shikoku Islands in Japan.In some areas,southern Honshu,and South Korea's Jeju Island.Under the CO2 doubling scenario,the optimal potential distribution area of the P.arguta will be significantly reduced,and there will be a tendency to migrate to the eastern and high altitudes regions.The analysis of the principal components of the 19 climatic factors affecting the distribution of species shows that moisture is the climatic factor that predominates the distribution of P.arguta.(2)With the aggravation of drought degree,the growth index of P.arguta also decreased more significantly.Under severe drought,the growth index of P.arguta was most inhibited,but the root to shoot ratio was the highest.The P.arguta was used to adapt to arid environment.The strategy of transferring biomass.At mild drought,the proline content of P.arguta rose first and then decreased,and SOD,POD,CAT,MDA,soluble protein and soluble sugar all showed an upward trend.Under medium and above drought stress,P.arguta showed SOD and CAT.Both soluble sugar and Pro were in a trend of rising first and then decreasing.POD and soluble protein showed a trend of rising afterwards,and MDA showed an upward trend.It showed that mild drought can increase the cell membrane permeability of the P.arguta,induce the protective enzyme system to clear the intracellular reactive oxygen species,make the cells produce osmoregulation substances to ensure the supply of water,moderate and severe drought damage to the P.arguta seedlings Larger,lower SOD and CAT,the activity of protective enzyme system was significantly reduced,soluble sugar and Pro were also decreased in the later period,indicating that moderate and severe drought can cause serious irreversible physiological damage to the physiological structure of P.arguta.(3)Pn was restricted by stomatal factors under mild drought stress,and non-stomatal factors were dominant under moderate and severe drought.Drought stress could inhibit the photochemical activity of P.arguta mite PSII.Fv/Fm,Fv'/Fm' and Fv/Fo all decreased significantly,indicating that P.arguta were photoinhibited and Fv/Fo was more sensitive to drought stress.The P.arguta can increase heat dissipation by increasing the NPQ.Moderate and severe drought can cause irreversible damage to the P.arguta 's PSII response system.