With the classical statistical and geostatistical methods,the study of the spatial distribution and its influence factors of soil water,salinity and organic matter was carried out for 0-70 cm soil layers in Manas River watershed.The results showed that the soil moisture data from all soil layers exhibited a normal distribution,with average values of 14.08%-21.55%.Geostatistical analysis revealed that the content of soil moisture had a moderate spatial autocorrelation with the ratios of nugget/sill ranging from 0.500 to 0.718,which implies that the spatial pattern of soil moisture is influenced by the combined effects of structural factors and random factors.Remarkable spatial distributions with stripped and mottled features were found for soil moisture in all different soil layers.The landform and crop planting had a relatively big influence on the spatial distribution of soil moisture;total soil salinity was high in east but low in west,and non-salinized soil and lightly salinized soil appeared at the northwest and southwest of the study area.Under the effect of reservoir leakage,the heavily salinized soils are widely distributed in the middle of the study area.The areas of the non-salinized and lightly salinized soils decreased gradually with soil depth increment,which is contrary to the case for saline soils that reached a maximum of 245.67 km2 at the layer of 50-70 cm.The types of soil salinization in Manas River watershed were classified into four classes:the sulfate,chloride-sulfate,sulfate-chloride and chloride.The sulfate salinized soil is most widely distributed in the surface layer.The areas of chloride-sulfate,sulfate-chloride,and chloride salinized soils increased gradually along with the increment of soil depth;the variation range of the average values of soil organic matter content was between 7.48%-11.33%.The ratios of nugget/sill reduced gradually from 0.698 to 0.299 with soil depth increment,which shows that the content of soil organic matter has a moderate spatial autocorrelation.The soil organi
Jilili ABUDUWAILIYang TANGMireban ABULIMITIDongWei LIULong MA
This paper focused on the water relations of two halophytes differing in photosynthetic pathway,phenotype,and life cycle:Karelinia caspica(Pall.) Less.(C3,deep-rooted perennial Asteraceae grass) and Atriplex tatarica L.(C4,shallow-rooted annual Chenopodiaceae grass).Gas exchange,leaf water potential,and growth characteristics were investigated in two growing seasons in an arid area of Xinjiang to explore the physiological adaptability of the two halophytes.Both K.caspica and A.tatarica showed midday depression of transpiration,indicating that they were strong xerophytes and weak midday depression types.The roots of A.tatarica were concentrated mainly in the 0-60 cm soil layer,and the leaf water potential(ΨL) increased sharply in the 0-20 cm layer due to high soil water content,suggesting that the upper soil was the main water source.On the other hand,K.caspica had a rooting depth of about 1.5 m and a larger root/shoot ratio,which confirmed that this species uptakes water mainly from deeper soil layer.Although A.tatarica had lower transpiration water consumption,higher water use efficiency(WUE),and less water demand at the same leaf water potential,it showed larger water stress impact than K.caspica,indicating that the growth of A.tatarica was restricted more than that of K.caspica when there was no rainfall recharge.As a shallow-rooted C4 species,A.tatarica displayed lower stomatal conductance,which could to some extent reduce transpiration water loss and maintain leaf water potential steadily.In contrast,the deep-rooted C3 species K.caspica had a larger root/shoot ratio that was in favor of exploiting groundwater.We concluded that C3 species(K.caspica) tapes water and C4 species(A.tatarica) reduces water loss to survive in the arid and saline conditions.The results provided a case for the phenotype theory of Schwinning and Ehleringer on halophytic plants.
Arbuscular mycorrhizal(AM)fungi penetrate the cortical cells of the roots of vascular plants,and are widely distributed in soil.The formation of these symbiotic bodies accelerates the absorption and utilization of mineral elements,enhances plant resistance to stress,boosts the growth of plants,and increases the survival rate of transplanted seedlings.We studied the effects of various arbuscular mycorrhizae fungi on the growth and development of licorice(Glycyrrhiza glabra).Several species of AM,such as Glomus mosseae,Glomus intraradices,and a mixture of fungi(G.mosseae,G.intraradices,G.cladoideum,G.microagregatum,G.caledonium and G.etunicatum)were used in our study.Licorice growth rates were determined by measuring the colonization rate of the plants by the fungi,plant dry biomass,phosphorus concentration and concentration of secondary metabolites.We established two cloned strains of licorice,clone 3(C3)and clone 6(C6)to exclude the effect of genotypic variations.Our results showed that the AM fungi could in fact increase the leaf and root biomass,as well as the phosphorus concentration in each clone.Furthermore,AM fungi significantly increased the yield of certain secondary metabolites in clone 3.Our study clearly demonstrated that AM fungi play an important role in the enhancement of growth and development of licorice plants.There was also a significant improvement in the secondary metabolite content and yield of medicinal compounds from the roots.
