Study On Characteristic Of Drought Resistance In Seeding Stage Of5Afforestation Tree Species In Rocky Guizhou Province

Due to periodic drought and poor soil water holding capacity in rockydesertification region, afforestation of tree species with strong water control anddrought resistance ability are beneficial to vegetation restoration in the region. Thisanalysis takes Dodonara viscosa （Linn.） Jacq., Folienia hodginsii （Dunn） Henry etThomas, Platycladus orientalis （Linn.） Franco, Zanthoxylum bungeanum Maxim, andCinnamonum camphora L. as study objects, through manipulating water availabilityfor plant growth in a greenhouse experiment, to determine their water, photosynthetic,growth characteristics and biomass under drought stress circumstance, and to carry onthe comprehensive evolution by using membership function. The principal conclusionsof this analysis are as follows:1. As drought stress increasing, the transpiration water consumption, leaf waterpotential and soil water potential of5tree species were gradually deceased. The watercontrol capacity was followed by Platycladus orientalis （Linn.） Franco> Zanthoxylumbungeanum Maxim> Cinnamonum camphora L.> Folienia hodginsii （Dunn） Henryet Thomas> Dodonara viscosa （Linn.） Jacq., with declining by up to52.9%. The leafwater was followed by Zanthoxylum bungeanum Maxim> Platycladus orientalis（Linn.） Franco> Folienia hodginsii （Dunn） Henry et Thomas> Dodonara viscosa（Linn.） Jacq.> Cinnamonum camphora L.. The soil water was followed byZanthoxylum bungeanum Maxim> Platycladus orientalis （Linn.） Franco> Dodonaraviscosa （Linn.） Jacq.> Folienia hodginsii （Dunn） Henry et Thomas> Cinnamonumcamphora L.. The leaf water potential and soil water potential of Cinnamonumcamphora L. decreased to the minimum, and were3.44times and21.90times thanthose of CK. It has been shown that Cinnamonum camphora L., Dodonara viscosa（Linn.） Jacq. and Folienia hodginsii （Dunn） Henry et Thomas have strong watercontrol and drought resistance ability. 2. Under sufficiency of water source, the light-response curve of photosynthesisof5tree species was successfully simulated with non-rectangular hyperbola model,and the fitting coefficients were more than0.98. The apparent quantum efficiency,maximum net photosynthetic rate and light saturation point of Folienia hodginsii（Dunn） Henry et Thomas were the highest among them. With the increasing droughtstress, the leaf chlorophyll relative contents of5tree species resulted in various change.The net photosynthetic rate, transpiration rate, and stomatal conductance decreasedgradually under middle and heavy drought stress（P<0.01）. The net photosyntheticrate decreased in order：Zanthoxylum bungeanum Maxim> Folienia hodginsii（Dunn） Henry et Thomas> Platycladus orientalis （Linn.） Franco> Dodonara viscosa（Linn.） Jacq.> Cinnamonum camphora L.. The transpiration rate decreased in order:Dodonara viscosa （Linn.） Jacq.> Zanthoxylum bungeanum Maxim> Platycladusorientalis （Linn.） Franco> Folienia hodginsii （Dunn） Henry et Thomas>Cinnamonum camphora L.. The Stomatal conductance decreased in order:Zanthoxylum bungeanum Maxim> Dodonara viscosa （Linn.） Jacq.> Platycladusorientalis （Linn.） Franco> Folienia hodginsii （Dunn） Henry et Thomas>Cinnamonum camphora L.. The water use efficiency increased in mild and middledrought, and decreased in heavy drought. Among them, the water use efficiency ofCinnamonum camphora L. decreased in heavy drought, which was still1.05times ofothers, showing that it has strong water control and drought resistance ability. Theintercellular CO₂concentration decreased in mild drought, but increased in middle andheavy drought, showing that the photosynthesis is affected by stomatal limitation inmild drought, and mainly by nonstomatic limitations in heavy drought. PSⅡelectronictransmit rate and the potential activity were restrained by drought stress. In mild andmiddle drought, the restrained degree was as follow: Platycladus orientalis （Linn.）Franco <Dodonara viscosa （Linn.） Jacq.<Folienia hodginsii （Dunn） Henry etThomas <Cinnamonum camphora L.<Zanthoxylum bungeanum Maxim, while inheavy drought, the restrained degree was as follow：Dodonara viscosa （Linn.） Jacq.<Folienia hodginsii （Dunn） Henry et Thomas <Platycladus orientalis （Linn.） Franco <Zanthoxylum bungeanum Maxim <Cinnamonum camphora L..3. Under drought stress, the most root amount and the longest root among5testedtree species were Platycladus orientalis （Linn.） Franco and Cinnamonum camphora L.respectively. The stems, tree height, crown width and shoot growth of Cinnamonum camphora L. were the highest overall as266.81cm. The total biomass of Cinnamonumcamphora L. was the biggest as104.77g. The root-shoot ration of Zanthoxylumbungeanum Maxim was the biggest as0.59.4. The paper comprehensively studies on the drought resistance with10datameasured by using membership function. In mild drought, the water control anddrought resistance ability was as follows: Dodonara viscosa（Linn.） Jacq.>Cinnamonum camphora L.> Platycladus orientalis （Linn.） Franco> Folieniahodginsii （Dunn） Henry et Thomas> Zanthoxylum bungeanum Maxim. In middledrought, the water control and drought resistance ability was as follows: Cinnamonumcamphora L.> Dodonara viscosa（Linn.） Jacq.> Platycladus orientalis （Linn.） Franco> Folienia hodginsii （Dunn） Henry et Thomas> Zanthoxylum bungeanum Maxim. Inheavy drought, the water control and drought resistance ability was as follows：Cinnamonum camphora L.> Dodonara viscosa（Linn.） Jacq.> Folienia hodginsii（Dunn） Henry et Thomas> Platycladus orientalis （Linn.） Franco> Zanthoxylumbungeanum Maxim. The survey has indicated that Cinnamonum camphora L. andDodonara viscosa（Linn.） Jacq. have stronger water control and drought resistanceability among the tested tree species, and are more capable to adapt to environment ofrocky desertification district.