Growth Law Of Cupressus Lusitanica And Its Characteristic Of Salt Tolerance And Drought Resistence

Cupressus lusitanica, a provenance from Mexico, is an evergreen arbor tree with highdrought tolerance and saline tolerance. With10provenances of Cupressus lusitanica fromMexico, D1(La presa), D2(Pinal de amoles),D3(La cienega)，D4(La cumbre del manzano)、D5(Dos aguas), D6(Camino a la mesa), D7(Ejido pio frio), D8(Comunal san francisco)、D9(Tequesquinahuac), D10(Ejido sierra de agua), their growth law, photosynthesischaracteristics and physiological characteristics under drought and saline diversity stress wasstudied and results are as follows:Cupressus lusitanica grew well in Nanjing and their growth of seedlings showed logisticcurve with growing days, whose R2was all more than0.98. There was great difference for theroot system and above ground growth among different types of provenance. For the D2provenance, it was with developed root system while the D5provenance was the highest. The D1provenance grew averagely for root, height and stem.Under low stress of saline, germination rate of D1, D10types improved a little while that forthe other tree types decreased a little. Germination energy, germination index, and seed viabilitydecreased with NaCl concentration. For one year seeding of Cupresses lusitanica, saline stressaffected their shape and growth of all types of provenance outstandingly. Height growth andground diameter growth was urged and its effect on height was higher than that of grounddiameter. There existed outstanding difference among10types of provenance.Light drought improved the growth of seeding and heavy drought urged the growth ofseeding of Cupressus lusitanica and the extent differed quietly according to its provenance.Drought urged the growth of Cupressus lusitanica, especially the D4provenance suffered themost seriously. Under heavy drought, there root growth decreased sharply except the root withdiameter between0.1-1.0mm grew well compared with the contrast. Light drought improved theaverage growth of root system. Drought also improved the growth of ground diameter ofCupressus lusitanica seedlings form the province of D1, D2, D3, D4, D5and D8.Their physiology and biochemistry reaction to light drought showed uniform while variedgreatly to heavy drought. At the early stage of drought stress, conductivity increased due to thedamage to the cell membrane by water loss. While in the lateral stage of drought, conductivitydecreased, which may be inferred due to the adaptability of seedlings to drought stress. With theextending of time and increase for drought stress, content of a（Chla）,b（Chlb）and （Chla＋Chlb）decreased and the ability for photosynthesis of leaves decreased correspondingly.Under drought stress,（MDA）in the needle leave of seeding of Cupressus Lusitania increased,among which, it was the highest for the D3provenance under T4drought level, whose MDAcontent in the leave was as high as290.41nmol/g. For the D5-D10provenances, drought stressmade the great damage when the soil water content was less than10%of the max field capacity of soil water. The activity of（POD）did not show outstanding change with the increase of droughtstress and time, showing strong function of protecting cell membrane. At the end of drought stress,it decreased suddenly, showing decline of antioxidant capacity. Proline content increased with thedrought stress at different levels for the ten provenances.For the10provenances, under drought stress of T1and T2level, soluble sugar content in theleaves increased at first and then decreased to its original level. For the D6,D8,D9and D10provenances, their soluble sugar content increased from1.0μ mol/g to3.5μ mol/g under T3and T4levels of drought stress, showing strong damage to seedlings. For the other provenances, therechange of soluble sugar content in the leaves varied similiarly with the contrast, showing lowdamage. For theD1and D7provenances, their soluble sugar content increased from1.0μ mol/g to4.5μ mol/g under T3and T4levels of drought stress, showing high damage.With principal component analysis, membership functions, weighting method, syntheticevaluation model of seeding saline and drought resistant ability was constituted. Instituting thevalues of height, ground diameter, volumetric water content, total content of chlorophyll, relativepermeability of cell membrane, mda and proline under saline stress and drought stress respectivelyinto the models, the order for drought resistance was D9、D5、D3、D10、D8、D7、D6、D1、D4、D2, while the order for saline resistance was D10（Ejido sierra de agua）and D3（La cienega）.