On Reserves of Hippophae rhamnoides L. Fruit on the Territory of the Zarafshan National Nature Park of Uzbekistan

The article is devoted to the study of stocks of Hippophae rhamnoides fruits on the territory of the Zarafshan National Park. Hippophae rhamnoides is a medicinal plant. This species is a naturally distributed plant. All parts of Hippophae rhamnoides are a source of biologically active substances, especially flavonoids, carotenoids, phytosterols and others. In the course of field studies, 10 monitoring sites were selected in the size of 10 × 10 m, and the productivity of one site in the amount of 10 × 10 averaged 51.33 ± 8.24 kg. According to the results obtained, it was revealed that the biological reserve averages 21.9 tons, respectively, the operational reserve is 13.14 tons and the volume of annual harvesting averages 1.31 tons. When the water level of the Zarafshan River rises, some plants are damaged.

Effects of Different Water Stresses on Eco-physiological Characteristics of Hippophae rhamnoides Seedlings

In order to examine the effects of the decrease of future precipitation on the eco-physiological characteristics of sea buckthorn (Hippophae rhamnoides Linn.) in Huangfuchuan Watershed in Nei Mongol, a water gradient experiment was conducted based on the four specially designed water supply levels, including normal precipitation, slight drought, drought and extreme drought. Results of ANOVE showed that different water gradients had a significant effect on (1) microhabitat factors, such as soil water content and soil temperature; (2) gas exchange, such as net photosynthetic rate, stomatal conductance and transpiration rate; (3) resource use efficiency; and (4) leaf water potential. Water use efficiency of H rhamnoides could increase under moderate water stress, i.e. drought condition, while its net photosynthetic rate and transpiration rate decreased. All kinds of eco-physiological characteristics proved H. rhamnoides seedlings under all water supplies were affected by water stress more or less and that mechanism of intrinsic physiological regulation in seedlings under the extreme drought conditions had the appearance of turbulence to a certain extent. Therefore, H rhamnoides seedlings in Huangfuchuan Watershed could not acclimate to extreme drought conditions.

Research on Rooting Cuttings of Hard Branch of Hippophae rhamnoides

Objective] In order to improve the survival rate of Hippophae rhamnoides hardwood cuttings, cultivate high-quality sea buckthorn seedlings. [Method] This pa-per took hard branches of Russian big fruit H. rhamnoides as material. The days of striking roots, rate of striking roots,root length and number of adventitious root were determined. [Result] The cuttings col ected from upper treetops were obviously inferi-or to the lower ones. Three years cutting is obviously better than one or two years. Cuttings from lower branches were not so good as the cuttings from upper branch-es. Base oblique incisions were clearly superior to paper-cover incision. The optimal length of cuttings was 20-25 cm. The rooting rate of cuttings was the highest by fast dipping with NAA of 50 mg/L. [Conclusion] The study provides theoretical basis for H. rhamnoides artificial cultivation.

Modular growth and clonal propagation of Hippophae rhamnoides subsp, sinensis in response to irrigation intensity

A multipurpose clone plant species, Hippophae rhamniodes has the capacity for indefinite longevity, although under successive drought stress it may often decline or die across large areas. Field trials were con- ducted over 2 years to examine the effects of varied irrigation intensities on modular growth and clonal propagation in a semi-arid area. Irrigation levels included a control, as well as two, four and six times the volume of water that was typically received via local annual average precipitation. Irrigation intensity significantly influenced clonal propagation capacity （number of daughter ramets）, aboveground modular growth （height, base diameter, and crown width）, belowground modular growth included root nodule dry weight, stretching capacity of lateral roots （length of the longest lateral roots, and diameter of first-grade lateral roots）, and branching intensity of lateral roots （number of lateral roots bifurcation grade, number of first- grade lateral roots）. The modular growth and the density of daughter ramets were small under non-irrigation or low irrigation, and became larger with increased irrigation intensity. Beyond a certain threshold, however, further increases in irrigation intensity resulted in a reversion to the development. The optimal irrigation intensities for growth and propagation were 3.48-5.29 times the volume of nominal local annual average precipitation. There were effects of irrigation intensities on the positive significant correlations between aboveground and belowground modular growths, and on clonal propagation capacities. Under various water treatments, H. rhamnoides may adapt to the environment through the regulation of growth and propagation. We concluded that water shortages act to weaken the growth and propagation of H. rhamniodes plantations.

Influence of soil moisture content on pullout properties of Hippophae rhamnoides Linn. roots

Plant root system plays an important role in preventing soil erosion and improving slope stability.However,its performance is significantly affected by soil moisture content,and the role of soil moisture in root reinforcement is not fully understood.In this study,the influence of soil moisture on root pullout properties was studied by experiments.Vertical in-situ pullout tests under four different levels of soil matric suction(12 kPa,18 kPa,24 kPa,30 kPa)were carried out on roots of sea buckthorn plants(Hippophae rhamnoides Linn.)which were artificially cultivated for 7 months.Diameter and length of the root system of sea buckthorn were investigated.The results showed that a very significant correlation was observed between root diameter(D)and root length(L)(P<0.01),and root diameter decreased with soil depth.When soil bulk density was constant,peak pullout force(F)and friction coefficient of root-soil interface(μ)decreased with increasing gravimetric soil moisture content in power functions.Soil moisture content significantly affected root pullout resistance because the increase of soil moisture content decreased the friction coefficient between the roots and soil.Root diameter at breakage point(Db)and length of root segment left in soil(Lb)were increased with soil moisture content.In addition,peak pullout force of the roots increased in a power function with root diameter at the soil surface(D0)and in a linear function with total root length(L).The results provided an experimental basis for quantifying the effects of soil moisture content on soil reinforcement by plant roots.

Effects of Total Flavonoids ofHippophae RhamnoidesL.on Intracellular Free Calciumin Cultured Vascular Smooth Muscle Cells of Spontaneously Hypertensive Rats and Wistar-Kyoto Rats

To explore the effects of total flavonoids of Hippophae rhamnoides L. （TFH） quercetin （Que） and isorhamnetin （Isor） on the intracellular free calcium （[Ca^2＋]） in vascular smooth muscle cells （VSMC） of spontaneously hypertensive rats （SHR） and Wistar-Kyoto rats （WKY）. Metheds： Fluo 3-acetoxymethylester（Fluo-3/AM） was used to observe the effects of TFH （100mg/L） and its essential monomers, namely Que （10^-4mol/L） and Isor （10^-4mol/L） on changes of [Ca^2＋]1 in cultured SHR and WKY VSMC （abbr. to Ca-SHR ＆ Ca-WKY） following exposure to high K^＋, norepinephrine （NE） and angiotensin Ⅱ （AngⅡ）, and to compare with the effects of verapamil （Ver）. Results： （1） TFH, Que and Isor had inhibitory effects on resting Ca-SHR （P〈0.05）, but had no significant effects on Ca-WKY （P〉0.05）. （2） High K^＋ could increase Ca-SHR more significantly than Ca-WKY （P〈0.05）; TFH, Que and Isor could inhibit the elevation of [Ca^2＋]1 induced by high K^＋ -depolarization, with the effects similar to that of Ver, and the effect on Ca-SHR was more significant than that on Ca-WKY （P〈0.05）. （3） NE and Ang Ⅱ could increase Ca-SHR more significantly than Ca-WKY （P〈0.05）, TFH, Que and Isor had remarkably inhibitory effect on the elevation of Ca-SHR and Ca-WKY induced by NE or Ang Ⅱ. （4） In the absence of extracellular Ca^2＋ , TFH, Que and Isor also had certain inhibitory effect on Ca-SHR and Ca-WKY induced by NE, and the effect on the former was more significant than that on the latter（P〈0.05）. Ceaclusiea： TFH, Que and Isor might decrease the levels of [Ca^2＋], in VSMCs by blocking both voltage-dependent calcium channels （VDC） and receptoroperated calcium channels （ROC） in physiological or pathological state, which may be one of the important mechanisms of their hypotensive and protective effects on target organs in patients with hypertension.

Molecular identification of sex in Hippophae rhamnoides L. using isozyme and RAPD markers

In many dioecious plants, gender affects economic value, breeding schemes and opportunities for commercial harvests. Hippophae rhamnoides L. is a dioecious plant species in which female genotypes are commercially preferred over male genotypes. Its berries have rich medicinal, nutritional and pharmaceutical properties because of their large amounts of vitamins, essential oils, proteins, fatty acids, free amino acids and flavanoids. Primary limitation for breeding H. rhamnoides L. is its dioecious nature, since gender cannot be identified by traditional methods. Therefore, some reliable and quick methods need to be developed. This commu- nication deals with the development of isozyme and RAPD markers for early sex identification in this dioecious tree. The isozyme analysis was conducted with four enzyme systems, viz. peroxidase, esterase, malate dehydrogenase and catalase. The peroxidase enzyme system produced a female specific sex marker, which successfully differentiated between the staminate and pistillate geno- types ofH. rhamnoides L. Thirty five random decamer primers were used in our study and one male sex linked marker was identified. OPD-20 （5＇-ACTTCGCCAC-3＇） displayed a band at 911 bp that expressed polymorphism between male and female genotypes. The staminate and pistillate genotypes could be distinguished using RAPD marker OPD-209n. These results revealed the immense poten- tial of peroxidase isozyme patterns and RAPD as genetic markers for sex identification in H. rhamnoides L.

Analysis of Effective Composition of Hippophae Rhamnoides L.

The vitamin E, proteins, amino acids, sugar, trace elements and fatty acids in the oil of Hippophae Rhamnoides L. seeds were quantitatively analyzed. Several methods for analyzing vitamin E were compared with each other and the content of gossypol in the oil was first determined.

Short-term responses to salinity of seabuckthorn (Hippophae rhamnoides L.) seedlings in the extremely cold and saline Qinghai region of China

The investigation of the mechanisms of plant adaptation to stressor action is one of the leading directions of current biological studies. To understand the mechanism of salt tolerance of seabuckthom （Hippophae rhamnoides L.） and identify its ability to cope with the salinity effect in the saline and extremely cold region of Qinghai, China, a test was conducted with two-year-old seedlings subjected to 0, 200, 400 and 600 mmol·L^-1 NaClsolutions for 30 d. The results show that with an increase in salinity, the biomass of H. rhamnoides seedlings clearly decreased. Leaf water potential （ψw） and relative water content （RWC） were significantly reduced under salinity, with severe water shortages appearing in leaves. At the same time, the total chlorophyll content declined markedly. When salinity increased and stress time prolonged, the net CO2 assimilation rate （A） significantly declined. Intercellular CO2 concentration （Ci） declined at first and was then followed by an increase over the stress time. We conclude that H. rhamnoides grown in the extremely cold and saline region of Qinghai has a certain resistance to salt, which can be planted at appropriate salinity levels.

Relationships between morphological descriptors and RAPD markers for assessing genetic variability in Hippophae rhamnoides L.

Knowledge of genetic relatedness among accessions of germplasm is necessary for the development of breeding strategies to produce improved cultivars. The present investigation on Hippophae rhamnoides was carried out to assess its genetic variability in Himachal Pradesh, India, by employing morphological and RAPD markers. Different areas of Himachal Pradesh were surveyed and eight sites were finally selected Twenty four genotypes were selected for further studies, i.e., three genotypes from each site. On the basis of morphological studies, the genotypes of the Ropa site （Kinnaur） were considered elite genotypes. To assess the variability at the molecular level, RAPD patterns were studied by random primers. The total number of bands amplified was 607, out of which 487 bands were identified as polymorphic, depicting 80.23 per cent variability. Six unique bands were produced from three primers （OPA- 05, OPA-10 and OPD-08） specific for five genotypes, including three genotypes of the Ropa site, Kinnaur District.

Molecular docking studies of anti-cancerous candidates in Hippophae rhamnoides and Hippophae salicifolia

Actinorhizal plants contain numerous antioxidants that may play a crucial role in preventing the formation of tumors.H-Ras p21,a member of the Ras-GTPase family,is a promising target to treat various kinds of cancers.An in silico docking study was carried out to identify the inhibitory potential of compounds of these plants against H-Ras by using Discovery Studio 3.5 and by using Autodock 4.2.Docking studies revealed that four compounds,isorhamnetin-7-rhamnoside,quercetin-3-glucoside-7-rhamnoside（present in H.rhamnoides）,zeaxanthin,and translutein（present in H.salicifolia） significantly bind with binding energies-17.1534,-14.7936,-10.2105 and-17.2217 Kcal/mol,respectively,even though they slightly deviate from Lipinski＇s rule.Absorption,distribution,metabolism,excretion and toxicity（ADME/tox） analyses of these compounds and their stereoisomers showed that they were less toxic and non-mutagenic.Amongst them,isorhamntein-7-rhamnoside showed hepatotoxicity.Hence,these compounds can be further investigated in vivo to optimize their formulation and concentration and to develop potential chemical entities for the prevention and treatment of cancers.

Comparative quantitative analysis of fruit oil from Hippophae rhamnoides(seabuckthorn) by qNMR, FTIR and GC–MS

Objective: To develop a qNMR method for quantitative analysis of triacylglycerols in fruit oil of Hippophae rhamnoides(seabuckthorn, SBT) and analyze commercial samples of SBT oils using GC–MS and FTIR.Methods: SBT fruit oil(IPHRFH) was extracted with hexane and the triglyceride(TAG) was isolated by vacuum liquid chromatography. Six different branded SBT oils purchased from e-commerce suppliers(Amazon) and in-house prepared SBT oil was analyzed by qNMR and fatty acyl composition of TAGs determined by using NMR. In-house oil was also analysed by GC–MS and FTIR spectroscopy.Results: The qNMR results showed that the oil contained 80.3% of triacylglycerol(TAG). The SBT oil TAGs comprised of linolenate 6.6%, palmitoleate/oleate 65.4%, and total saturated fatty acyl chain including palmitate 28% as determined by qNMR. GC–MS analysis revealed that the major acyl functionalities present in the TAG were palmitoleic acid 36.5%, oleic acid 12.9%, palmitic acid 21.2%, and linoleic acid 18%. Of the six commercial samples analyzed, samples from only one supplier(SW) were fruit oil;All others were the seed oils or mix of fruit oil and seed oil. The labels for samples except for the SW did not indicate whether it was fruit oil or seed oil.Conclusion: The results suggest that SBT oil should be analyzed by combination of GC–MS, FTIR and qNMR for factual content of free fatty acid or TAGs, which are chemically different in nature and affect the quality of oil. GC–MS showed the content of omega free fatty acids after hydrolysis, while qNMR and FTIR showed the content of TAGs. The major acyl functionalities found in SBT fruit oil TAGs are palmitoleate/palmitate/oleate, while linoleate and linonelate make up a minor fraction. Furthermore,analysis of commercial samples showed discrepancies between label claims and actual content.

沙棘(Hippophae rhamnoides)对经客土改良石漠化土壤的适应性

石漠化地区基岩裸露、砾石堆积,水土流失严重,土壤与植被覆盖率低,因此引发一系列的生态恶化问题,而客土恢复植被是一项快速有效的治理途径。本试验在贵州毕节地区实施,以当地黄壤客土(T1,黄壤与砾石比为1∶1;T2,黄壤与砾石比为2∶1;T3,黄壤与砾石比为3∶1;T4,黄壤与砾石比为1∶0)改良石漠化,从耐瘠薄的灌木——沙棘(Hippophae rhamnoides)为试材,探究其幼苗在客土改良后的石漠化土壤中的适应性,栽种期为2年。结果表明:客土处理对沙棘幼苗的冠幅、粗根的根长密度、粗根根重密度均无显著影响;百分之百客土即T4会显著抑制沙棘株高、根系生物量,显著促进细根比根长的增长;当黄壤与砾石比例1/2—2/3时,2年后沙棘细根的根重密度与土壤含水量均会显著增加;当黄壤与砾石比大于2/3时会显著抑制沙棘根系长度总和的增加,且2年后对土壤水分改善作用不显著;沙棘根系指标与2年后的土壤含水量呈现出显著的相关关系。在贵州毕节地区客土改良石漠化时,并非客土越多越好,当黄壤与砾石的比例在1/2—2/3时,栽种沙棘2年可显著改善土壤含水量。

Preparation of a Hippophae rhamnoides Linn oil nanoemulsion and the visualization of its transdermal permeation

A Hippophae rhamnoides Linn oil nanoemulsion was developed, and its physicochemical properties and in vitro transdermal characteristics were investigated. Then its skin irritation was investigated. The optimum Hippophae rhamnoides Linn oil nanoemulsion prescription was determined using Cremophor EL as an emulsifier, Transcutol P as a co-emulsifier, and isopropyl myristate(IPM) as the oil phase(IPM%: Cremophor EL%: Hippophae rhamnoides Linn oil%= 5:16:20, Km = 4:1). The prepared Hippophae rhamnoides Linn oil nanoemulsion was pale yellow and transparent. Globular droplets were observed under a transmission electron microscope(TEM). The average particle size was 52.2±4.8 nm. The loading capacity was 10.68%, and the oil-in-water(O/W) type nanoemulsion was stable after centrifugation. The CLSM results showed that the fluorescence intensity of the OB Hippophae rhamnoides Linn oil nanoemulsion group was stronger than that of the Hippophae rhamnoides Linn oil cream and Hippophae rhamnoides Linn oil groups in each layer of skin. The study also showed that skin surface treated with the Hippophae rhamnoides Linn oil nanoemulsion had strong fluorescence. The skin depth had weak fluorescence, while the areas near the hair follicle and its appendages had the strongest fluorescence. The skin irritation test showed that the prepared Hippophae rhamnoides Linn oil nanoemulsion was applied to the normal and damaged skin of the rabbit, and there was no apparent redness and swelling. These results suggested that the nanoemulsion coated with Hippophae rhamnoides Linn oil was a potential delivery system for skin disorders.

Hippophae rhamnoides L.leaves extract enhances cell proliferation and neuroblast differentiation through upregulation of intrinsic factors in the dentate gyrus of the aged gerbil

Background Hippophae rhamnoides L.（HL） exerts antioxidant activities against various oxidative stress conditions.In this study,we investigated effects of extract from HL leaves （HLE） on cell proliferation and neuroblast differentiation in the subgranular zone （SGZ） of the dentate gyrus （DG） of aged gerbils.Methods Aged gerbils （24 months） were divided into vehicle （saline）-treated-and HLE-treated-groups.The vehicle and HLE were orally administered with 200 mg/kg once a day for 20 days before sacrifice.Cell proliferation and neurobiast differentiation were examined in the DG using Ki67 and doublecortin （DCX）,respectively.We also observed changes in immunoreactivities of superoxide dismutase 1 （SOD1） and superoxide dismutase 2 （SOD2）,brain-derived neurotrophic factor （BDNF）,and phospho-glycogen synthase kinase-3-beta （p-GSK-3β） to examine their relation with neurogenesis using immunohistochemistry.Results The administration of HLE significantly increased the number of Ki67-positive cells and DCX-positive neuroblasts with well-developed processes in the SGZ of the DG of the HLE-treated-group.In addition,immunoreactivities of SOD1,SOD2,BDNF,and p-GSK-3β were significantly increased in granule and polymorphic cells of the DG in the HLE-treated-group compared with those in the vehicle-treated-group.Conclusions HLE treatment significantly increased cell proliferation and neuroblast differentiation,showing that immunoreactivities of SOD1,SOD2,BDNF,and p-GSK-3β were significantly increased in the DG.These indicate that increased neuroblast differentiation neurogenesis may be closely related to upregulation of SOD1,SOD2,BDNF,and p-GSK-3β in aged gerbils.

Effects of Ultra-drying on Vigor and Physiological characteristics of Hippophae rhamnoides Seeds

Studies of ultra-drying and accelerated aging on Hippophae rhamnoides seeds from the arid and semiarid areas of northwest China were conducted. The results showed that H. rhamnoides seeds had higher desiccation endurance. When seeds were desiccated to 26 g/kg, their germination percentage, vigor indices and enzyme activity could be retained. After 30-day accelerated aging, ultra-dried seeds had better anti-aging ability and storability compared to natural dried seeds, and the best choice for the MC of seed was 34 g/kg. Accordingly, ultra-drying treatment could improve the storability.

Spatial distribution of Holcocerus hippophaecolus (Lepidoptera: Cossidae) pupae in a seabuckthorn (Hippophae rhamnoides) stand

The seabuckthorn carpenter moth,Holcocerus hippophaecolus,which has a generation time of four years,is recently becoming one of the major pests of the seabuckthorn(Hippophae rhamnoides)in Inner Mongolia,Liaoning,Shanxi,Ningxia and Shaanxi of China(Hua et al.,1990).The larvae of the H.hippophaecolus mainly damage the stems and roots of the seabuckthorn,and the mature larvae pupate in the soil.The spatial distribution of the pupae was analyzed by using biostatistics and geostatistics in order to effectively control the insect and further study the spatial distribution of the population.Results show that most of the pupae(90%)had an eclosion time span from early June to the end of July.The sex ratio of the pupae was nearly 1:1 in the woodland samples.In addition,24.3%of the 971 trees investigated had pupae and it ranged from 0 to 4 per tree within a distance of 1.3 m from the base of the stem.90%of the pupae were aggregated within a distance of 1 m from the base of the stem.The pupae show intense spatial aggregation in the sampled woodland which had an 11.1 m spatial dependence and a 90.7%intensity in the local spatial continuity.Moreover,the population presented an intensive spotted distribution and many aggregated spots were found in the woodlands.As for the relationship between grid size and variogram of the pupae,the variations in the range,the intensity of local spatial continuity and the sill were all very low or non-existent when the grid size was 5 m,6 m or 7 m.Whereas,the value of the decisive coefficient was the biggest when the grid size was 5 m making it the ideal grid size.

Fruits foraging patterns and seed dispersal effect of frugivorous birds on Hippophae rhamnoides sinensis

Behaviors of 18 species of birds eating fruits of Hippophae rhamnoides spp.sinensis were observed from September 2003 to March 2004.Their foraging patterns were found to be very different and can be divided into five classes:(1)direct swallowing the fruits on crown of the shrubs and sometimes regurgitating seeds soon after;(2)carrying the fruits to their perching sites and swallowing;(3)pecking the fruits from the shrubs to the ground,eating pulp and seeds but leaving pericarp;(4)pecking through the pericarp,eating pulp and leaving pericarp and seeds;(5)pecking through the pericarp on the top of fruits,and only eating seeds.These foraging patterns have different effects on seed dispersal of H.rhamnoides spp.sinensis.The germina-tion experiment of three groups of seeds(seeds from feces,dry fruits and extracted seeds from dry fruits)was carried out.Although ingestion processes of birds had some adverse effects on the seed germination of H.rhamnoides spp.sinensis,the seeds from feces still have a relatively higher germination ratio.H.rhamnoides spp.sinensis provides food to a variety of frugivorous birds,and the birds disperse its seeds.Thus,a mutually beneficial relationship between the bird and the seed is formed.

Characterization and comparison of chloroplast genomes from two sympatric Hippophae species(Elaeagnaceae)

The genus Hippophae includes deciduous shrubs or small trees,which provide many ecological,economic,and social benefi ts.We assembled and annotated the chloroplast genomes of sympatric Hippophae gyantsensis(Rousi)Lian and Hippophae rhamnoides Linn subsp.yunnanensis Rousi and comparatively analyzed their sequences.The fulllength chloroplast genomes of H.gyantsensis and H.rhamnoides subsp.yunnanensis were 155,260 and 156,415 bp,respectively;both featured a quadripartite structure with two copies of a large inverted repeat(IR)separated by small(SSC)and large(LSC)single-copy regions.Each Hippophae chloroplast genome contained 131 genes,comprising 85 protein-coding,8 ribosomal RNA,and 38 transfer RNA genes.Of 1302 nucleotide substitutions found between these twogenomes,824(63.29%)occurred in the intergenic region or intron sequences,and 478(36.71%)were located in the coding sequences.The SSC region had the highest mutation rate,followed by the LSC region and IR regions.Among the protein-coding genes,three had a ratio of nonsynonymous to synonymous substitutions(Ka/Ks)>1 yet none were signifi-cant,and 66 had Ka/Ks<1,of which 46 were signifi cant.We found 20 and 16 optimal codons,most of which ended with A or U,for chloroplast protein-coding genes of H.gyantsensis and H.rhamnoides subsp.yunnanensis,respectively.Phylogenetic analysis of fi ve available whole chloroplast genome sequences in the family Elaeagnaceae—using one Ziziphus jujube sequence as the outgroup—revealed that all fi ve plant species formed a monophyletic clade with two subclades:one subclade consisted of three Hippophae species,while the other was formed by two Elaeagnus species,supported by 100%bootstrap values.Together,these results suggest the chloroplast genomes among Hippophae species are conserved,both in structure and gene composition,due to general purifying selection;like many other plants,a signifi cant AT preference was discerned for most proteincoding genes in the Hippophae chloroplast genome.This study provides a valuable reference tool for future research on the general characteristics and evolution of chloroplast genomes in the genus Hippophae.

Sap flow characteristics and physiological adjustments of two dominant tree species in pure and mixed plantations in the semi-arid Loess Plateau of China

It is essential to understand the water consumption characteristics and physiological adjustments of tree species under drought conditions,as well as the effects of pure and mixed plantations on these characteristics in semi-arid regions.In this study,the normalized sap flow(SFn),leaf water potential,stomatal conductance(gs),and photosynthetic rate(Pr)were monitored for two dominant species,i.e.,Pinus tabuliformis and Hippophae rhamnoides,in both pure and mixed plantations in a semi-arid region of Chinese Loess Plateau.A threshold-delay model showed that the lower rainfall thresholds(RL)for P.tabuliformis and H.rhamnoides in pure plantations were 9.6 and 11.0 mm,respectively,and the time lags(τ)after rainfall were 1.15 and 1.76 d for corresponding species,respectively.The results indicated that P.tabuliformis was more sensitive to rainfall pulse than H.rhamnoides.In addition,strong stomatal control allowed P.tabuliformis to experience low gsand Prin response to drought,while maintaining a high midday leaf water potential(Ψm).However,H.rhamnoides maintained high gsand Prat a lowΨmexpense.Therefore,P.tabuliformis and H.rhamnoides can be considered as isohydric and anisohydric species,respectively.In mixed plantation,the values of RLfor P.tabuliformis and H.rhamnoides were 6.5 and 8.9 mm,respectively;and the values ofτwere 0.86 and 1.61 d for corresponding species,respectively,which implied that mixed afforestation enhanced the rainfall pulse sensitivity for both two species,especially for P.tabuliformis.In addition,mixed afforestation significantly reduced SFn,gs,and Prfor P.tabuliformis(P<0.05),while maintaining a high leaf water potential status.However,no significant effect of mixed afforestation of H.rhamnoides was observed at the expense of leaf water potential status in response to drought.Although inconsistent physiological responses were adopted by these species,the altered water consumption characteristics,especially for P.tabuliformis indicated that the mixed afforestation requires further investigation.