Polyploidy and invasion success: trait trade-offs in native and introduced cytotypes of two Asteraceae species

Invasion success is favoured by the introduction of pre-adapted genotypes. In addition, novel pressures in the introduced range may lead to phenotypic changes related to fitness or competitive ability of introduced plants. Polyploidy appears to be over-represented in invasive plants, but differences between cytotypes in growth strategies including trade-offs among plant traits have received little attention so far in the context of biological invasions. We grew Centaurea stoebe L. and Senecio inaequidens D.C. in a greenhouse experiment to test for differences in fitness (shoot biomass, reproductive output) and competitive ability (vegetative size, specific leaf area, leaf dry matter content, root–shoot ratio) between diploid and polyploid cytotypes as well as between native and introduced plants. For both species, diploid and tetraploid genotypes occur in the native range, whereas only tetraploids are present in the introduced range. In the native range of both species, diploid and tetraploid genotypes had different growth strategies. Tetraploid genotypes of C. stoebe and S. inaequidens had, respectively, higher specific leaf area and stem height than diploid ones. Thus, for both species, native tetraploids appeared more competitive than native diploids, which could explain, at least partially, the invasion success of the pre-adapted tetraploid genotypes. The comparison of native and introduced tetraploid genotypes revealed differences in traits linked to competitive ability, which could be linked to novel selection in the new environment. In S. inaequidens, we found evidence for a competition-colonisation trade-off, whereas persistence of C. stoebe in the new range seemed to be linked to a competition-defence trade-off.     

Geographical distribution of Allium oleraceum cytotypes in Finland and Sweden

Chromosome numbers from a total number of 226 populations of Allium oleraceum were determined in Finland, Sweden and seven other countries. Two different chromosome numbers or cytotypes were found, tetraploids (2n = 32) and pentaploids (2n = 40). In Finland, samples were collected for chromosome counts from a total of 190 populations, which fairly well covers the distribution area of the species in Finland. The majority of the populations of A. oleraceum in Finland contained only one of the two cytotypes. A clear pattern in the geographical distribution of the cytotypes could be distinguished. The pentaploid cytotype predominates in the Åland Islands and in the archipelago of Regio aboënsis. The tetraploid cytotype predominates on the mainland of the Regio aboënsis and along the coast of the Nylandia. In south Häme, all studied native populations were of the tetraploid cytotype. Of all the studied populations in Finland 43.7% were tetraploid and 51.6% pentaploid. A few mixed populations with both tetraploid and pentaploid plants occurring in the same population were also found (4.7%). The chromosome numbers of 19 populations of A. oleraceum from the southern part of Sweden were pentaploids, with the exception of one tetraploid population. It seems that the pentaploid cytotype is predominant in Sweden, but no conclusions about a geographical pattern between the two cytotypes could be drawn. Based on the occurrence of the cytotypes, it is suggested that the pentaploid cytotype might have spread to Finland from the Swedish east coast via the Åland Islands to Kaland on the Finnish west coast and along the coast of Nyland to the archipelagos of Kotka and Hamina in Karelia australis. The tetraploid populations in south Häme are clearly connected to Iron Age activity and to old inland trade routes, and may be of eastern origin.     

The differential impact of a native and a non‐native ragwort species (Senecioneae) on the first and second trophic level of the rhizosphere food web

Whereas the impact of exotic plant species on above‐ground biota is relatively well‐documented, far less is known about the effects of non‐indigenous plants on the first and second trophic level of the rhizosphere food web. Here, rhizosphere communities of the invasive narrow‐leaved ragwort Senecio inaequidens and the native tansy ragwort Jacobaea vulgaris, co‐occurring in three semi‐natural habitats are compared. For both species, two life stages were taken into consideration. Quantitative PCR assays for the analyses of bacterial and fungal communities at a high taxonomic level were optimized, and it was investigated whether changes in the primary decomposer community were translated in alterations in bacterivorous and fungivorous nematode communities. In contrast to J. vulgaris, small but significant reductions were observed for Actinobacteria and Bacteroidetes (both p < 0.05) in case of the invasive S. inaequidens. More pronounced changes were detected for the overall nematode community density, and, more specifically, for the bacterivorous genus Anaplectus and the family Monhysteridae (both p < 0.05), as well as the necromenic Pristionchus (p < 0.001). At high taxonomic level, no differences were observed in fungal rhizosphere communities between native and non‐native ragwort species. The impact of plant developmental stages on rhizosphere biota was prominent. The overall bacterial and fungal biomasses, as well as a remarkably consistent set of constituents (Actinobacteria, α‐ and β‐Proteobacteria and Bacteroidetes) were negatively affected by plant stage for both ragwort species. Although later developmental stages of plants generally coincided with lower levels for individual nematode taxa, densities of the fungivorous genera Diphtherophora and Tylolaimophorus remain unaltered. Hence, even at a high taxonomic level, differential effects of native and non‐native ragwort could be pinpointed. However, plant developmental stage has a more prominent impact and this impact was similar in nature for both native and non‐native ragwort species.     

Polyploidy: a missing link in the conversation about seed transfer of a commonly seeded native grass in western North America

The use of local, native plant materials is now common in restoration but testing for polyploidy in seed sources is not. Diversity in cytotypes across a landscape can pose special seed transfer challenges, because the methods used to determine genetically appropriate materials for seed transfer do not account for cytotypic variation. This lack of consideration may result in mixing cytotypes through revegetation, which could reduce long‐term population viability. We surveyed nine populations of a native bunchgrass, Pseudoroegneria spicata, in three EPA Level III Ecoregions in the western United States to determine the frequency of polyploidy, whether there are differences in traits (phenotype, fecundity, and mortality) among plants of different cytotypes, and whether cytotype frequency varies among ecoregions. We assessed trait variation over 2 years in a common garden and determined ploidy using flow cytometry. Polyploidy and mixed cytotype populations were common, and polyploids occurred in all ecoregions. Four of the nine populations were diploid. The other five had tetraploids present: three had only tetraploid individuals whereas two had mixed diploid/tetraploid cytotypes. There was significant variation in traits among cytotypes: plants from tetraploid populations were larger than diploid or mixed populations. The frequency and distribution of cytotypes make it likely that seed transfer in the study area will inadvertently mix diploid and polyploid cytotypes in this species. The increasing availability of flow cytometry may allow ploidy to be incorporated into native plant materials sourcing and seed transfer.     

An experimental investigation of life history and plasticity in two cytotypes of Polygonum aviculare L. subsp. aviculare that coexist in an abandoned arable field

Polygonum aviculare subsp. aviculare is an annual selfing weed common in abandoned arable fields where it occurs as a widespread hexaploid cytotype (6x=60) and a rarer tetraploid cytotype (4x=40). The basis of phenological differentiation between the two cytotypes observed in a natural population where they coexist was examined in a greenhouse experiment comprising six soil conditions consisting of factorial combinations of two levels of fertility and three pot sizes. The environmental and genetic component of variation in 11 life history and morphological traits was quantified. Even though all traits except life span were plastic the two cytotypes appear to have evolved contrasting life history strategies and it is inferred that this can account for the temporal niche differentiation observed in the abandoned field during the first year of dereliction. Tetraploids are short-lived plants allocating a high proportion of their biomass to reproduction and completing their life cycle before July when the plant cover is sparse. Hexaploids are larger, later flowering, longer lived, plants with a lower reproductive effort and a higher final seed yield; it is inferred that these traits enable the hexaploids to compete successfully with the dense herbaceous layer of summer annuals that develops in the course of the first year of secondary succession. Differentiation in phenotypic plasticity between the two cytotypes was interpreted as indicative of higher opportunism and lower tolerance of poor soils and restricted rooting space in the hexaploid compared to the tetraploid cytotype.     

AUTOPOLYPLOIDY IN HEUCHERA MICRANTHA (SAXIFRAGACEAE)

Heuchera micrantha (Saxifragaceae) is a morphologically variable species comprising five varieties: diversifolia, erubescens, hartwegii, micrantha, and pacifica. Both diploids (2n = 14) and tetraploids (2n = 28) occur within the species. The tetraploid cytotype occupies the central portion of the geographic range of the species, whereas diploids occur primarily in the southern and northern portions of the range. Both diploids and tetraploids have been detected within vars. diversifolia, pacifica, and hartwegii. All counts for vars. erubescens and micrantha are diploid and tetraploid, respectively. Several lines of evidence suggest that tetraploid H. micrantha is of autopolyploid origin. The species is distinct morphologically and is also well separated geographically from other closely related species in subsection Micranthae. The two cytotypes are karyologically identical, possess nearly the same suite of allozymes, and have a very high genetic identity (Ī = 0.971). Significantly, an earlier study documented tetrasomic inheritance in the tetraploid cytotype. Following theoretical expectations, the mean number of alleles per locus, proportion of loci that are polymorphic, and observed heterozygosity are significantly higher for the autotetraploid than for the diploid. The occurrence of both cytotypes in three of the varieties suggests that autopolyploidy may have occurred several times independently in H. micrantha. This was further substantiated by discriminant analysis using morphological characters, which provided evidence for a minimum of two separate origins for the autopolyploid cytotype.     

国产毛茛科驴蹄草属两种植物的细胞学研究

为探讨国产毛茛科(Ranunculaceae)驴蹄草属(Caltha L.)植物的细胞学特征,对驴蹄草(C.palustris L.)3个居群和花葶驴蹄草(C.scaposa Hook.f.&Thoms.)5个居群进行了细胞学研究。驴蹄草贵州纳雍居群的染色体数目为2n=32(四倍体),两个云南中甸居群的染色体数目均为2n=64(八倍体)。花葶驴蹄草四川红原、康定、石渠居群的染色体数目均为2n=32(四倍体),该数目为首次报道;西藏林芝和云南德钦居群的染色体数目均为2n=64(八倍体)。驴蹄草的染色体比花葶驴蹄草大。这两种植物的32或64条染色体分别以4条或8条为单位大致能够排列为8组同源染色体,但同一组内的染色体经常具有明显的异形性(heteromorphy),不同居群的核型组成多少具有差异。同时,还分析了驴蹄草和花葶驴蹄草的不同倍性细胞型在我国的地理分布式样。     

Impaired male meiosis, morphology and distribution pattern of different cytotypes of Bupleurum lanceolatum Wall. (Apiaceae) from the Western Himalayas

Detailed male meiosis, critical morphological observations and distribution pattern of diploid as well as tetraploid cytotypes of the Western Himalayan species, Bupleurum lanceolatum have been evaluated at present. A diploid (n = 8) cytotype is reported from Kashmir, whereas, both diploid (n = 8) and tetraploid (n = 16) cytotypes are available from two districts Kangra and Sirmaur of Himachal Pradesh. Out of these, the tetraploid cytotype makes new addition for the species on a worldwide basis. As per behavior, a tetraploid cytotype is characterized by abnormal meiosis leading to high pollen sterility and size variation of the pollen grains. Morphologically, tetraploids are noted to be luxuriant in comparison to the diploids.     

Local pre‐adaptation to disturbance and inbreeding–environment interactions affect colonisation abilities of diploid and tetraploid Centaurea stoebe

• Primary colonisation in invasive ranges most commonly occurs in disturbed habitats, where anthropogenic disturbance may cause physical damage to plants. The tolerance to such damage may differ between cytotypes and among populations as a result of differing population histories (adaptive differentiation between ruderal verus natural habitats). Moreover, founder populations often experience inbreeding depression, the effects of which may increase through physical damage due to inbreeding–environment interactions. We aimed to understand how such colonisation processes differ between diploid and tetraploid Centaurea stoebe populations, with a view to understanding why only tetraploids are invasive.
• We conducted a clipping experiment (frequency: zero, once or twice in the growing season) on inbred versus outbred offspring originating from 37 C. stoebe populations of varying cytotype, range and habitat type (natural versus ruderal). Aboveground biomass was harvested at the end of the vegetation period, while re‐sprouting success was recorded in the following spring.
• Clipping reduced re‐sprouting success and biomass, which was significantly more pronounced in natural than in ruderal populations. Inbreeding depression was not detected under benign conditions, but became increasingly apparent in biomass when plants were clipped. The effects of clipping and inbreeding did not differ between cytotypes.
• Adaptive differentiation in disturbance tolerance was higher among populations than between cytotypes, which highlights the potential of pre‐adaptation in ruderal populations during early colonisation on anthropogenically disturbed sites. While the consequences of inbreeding increased through clipping‐mediated stress, they were comparable between cytotypes, and consequently do not contribute to understanding the cytotype shift in the invasive range.

     

AUTOPOLYPLOIDY IN TOLMIEA MENZIESII (SAXIFRAGACEAE)

Tolmiea menziesii comprises diploid (2n = 14) and tetraploid (2n = 28) cytotypes that differ in geographic distribution. Chromosome counts now available indicate that the diploid and tetraploid cytotypes occupy the southern and northern portions, respectively, of the range of Tolmiea. Available data strongly suggest that Tolmiea represents an example of autopolyploidy. The genus is monotypic and very distinct in both floral and vegetative morphology among genera of tribe Saxifrageae. Infraspecific taxa have not been recognized in T. menziesii, and the two cytotypes appear to be indistinguishable morphologically. Karyotypic, flavonoid chemical, and preliminary allozymic data are all in agreement with the contention that the tetraploid cytotype is of autopolyploidal origin.     

New Cases of Parthenogenesis and Polyploidy in the Genus Ramazzottius (Tardigrada,Hypsibiidae) and a Hypothesis Concerning Their Origin

Summary

Specimens of the genus Ramazzottius Binda and Pilato, 1986 (Eutar-digrada, Hypsibiidae) were obtained from 2 moss and 1 lichen sample(s) collected in the Emilian Apennine Mountains. R. tribulosus was only found in one sample, whereas R. oberhaeuseri was found in all three. The first species had only diploid specimens, with 6 bivalents during the first meiotic division; the second had only females showing various polyploid cytotypes in addition to the diploid bisexual cytotype cited for this area. One of the triploid and the tetraploid cytotypes were characterized by the presence of univalents at oocyte metaphase. In contrast, another cytotype had “bivalents” in triploid number. Though the large number of cytotypes found in a single sample may be attributed to chance, it is better explained by an in loco origin, at least in some cases.     

广东省本地油茶和引种油茶根际土壤微生物群落特征

【背景】近年来,油茶低效林面积较大,根际土壤微生物影响林木抗性和生长,对林业可持续发展具有重要意义。【目的】了解广东省本地油茶和引种油茶根际土壤微生物群落特征。【方法】利用高通量测序分析油茶根际土壤微生物群落组成。【结果】油茶根际土壤细菌有26门77纲201目377科593属676种,真菌有14门50纲121目266科502属631种。油茶根际土壤中的优势细菌为酸杆菌门和变形菌门,优势真菌为子囊菌门和担子菌门。两种油茶根际土壤微生物组成差异显著,本地油茶根际土壤的细菌多样性显著高于引种油茶。在门水平上,脱硫杆菌门细菌和罗兹菌门、被孢霉门真菌的相对丰度在两种油茶间差异显著,Amorphotheca在本地油茶根际土壤中特异性富集。两种油茶根际土壤细菌碳代谢相对丰度差异显著,真菌以腐生营养型为主,其次为病理营养型和共生营养型。本地油茶根际土壤中显著富集土壤腐生菌,而共生营养型真菌(尤其是丛枝菌根真菌)相对丰度(6.43%)显著低于引种油茶中(21.83%)。此外,有机质和养分含量是影响油茶根际土壤微生物群落的关键因子。【结论】本地油茶和引种油茶根际土壤微生物群落组成和结构差异显著,Amorp...     

An experimental test of local adaptation among cytotypes within a polyploid complex

The geographic distributions of polyploids suggest they can have distinct and sometimes broader niches compared to diploids. However, relatively few field experiments have investigated whether range differences are associated with local adaptation or reflect other processes, such as dispersal limitation. In three years of transplants across the elevational ranges of five cytotypes in the Claytonia perfoliata complex, we found evidence for local adaptation. In at least one study year germination was higher within the natural range for each cytotype, and four of the five cytotypes attained larger biomass within their natural range. Fitness within and beyond range varied across years, with two instances of cytotypes showing higher fitness beyond the range, highlighting a potential role of temporal variability in cytotype differentiation. Polyploids as a group did not outperform diploids, but the cytotype with highest fitness across environments was a hexaploid reported to be invasive. Our results suggest that differences in geographic ranges within the C. perfoliata complex reflect local adaptation of cytotypes. Although we did not find a general polyploid advantage, our findings support the idea that occasional polyploid cytotypes exhibit high fitness relative to other cytotypes, and contribute to growing evidence supporting ecological differentiation of cytotypes within polyploid complexes.     

An invasive aster (Ageratina adenophora) invades and dominates forest understories in China: altered soil microbial communities facilitate the invader and inhibit natives

Exotic plant invasion may alter underground microbial communities, and invasion-induced changes of soil biota may also affect the interaction between invasive plants and resident native species. Increasing evidence suggests that feedback of soil biota to invasive and native plants leads to successful exotic plant invasion. To examine this possible underlying invasion mechanism, soil microbial communities were studied where Ageratina adenophora was invading a native forest community. The plant–soil biota feedback experiments were designed to assess the effect of invasion-induced changes of soil biota on plant growth, and interactions between A. adenophora and three native plant species. Soil analysis showed that nitrate nitrogen (NO₃⁻-N), ammonium nitrogen (NH₄⁺-N), and available P and K content were significantly higher in a heavily invaded site than in a newly invaded site. The structure of the soil microbial community was clearly different in all four sites. Ageratina adenophora invasion strongly increased the abundance of soil VAM (vesicular-arbuscular mycorrhizal fungi) and the fungi/bacteria ratio. A greenhouse experiment indicated that the soil biota in the heavily invaded site had a greater inhibitory effect on native plant species than on A. adenophora and that soil biota in the native plant site inhibited the growth of native plant species, but not of A. adenophora. Soil biota in all four sites increased A. adenophora relative dominance compared with each of the three native plant species and soil biota in the heavily invaded site had greater beneficial effects on A. adenophora relative dominance index (20% higher on average) than soil biota in the non-invaded site. Our results suggest that A. adenophora is more positively affected by the soil community associated with native communities than are resident natives, and once the invader becomes established it further alters the soil community in a way that favors itself and inhibits natives, helping to promote the invasion. Soil biota alteration after A. adenophora establishment may be an important part of its invasion process to facilitate itself and inhibit native plants.     

Studies on the Asian Eupatorias

Analysis of 265 plants derived from 13 sites in the Rokko Mountains shows that the widely distributed eastern AsianEupatorium chinense var.simplicifolium consists of seven cytotypes. These polymorphic karyotypes comprise four levels of ploidy based on X=10 and partial deficiency, occurring either alone or in combination. The polyploid cytotypes exhibit anomalous meiosis and highly variable pollen stainability in contrast to the nearly-normal behaviour of the diploid. The polyploid cytotypes were revealed as being agamospermous. They are readily distinguishable from the diploid cytotypes by several morphological characters and by growth habits closely related to their respective niches. Two or more cytotypes occurred in all sites examined, the most common being the coexistence of triploid and tetraploid cytotypes. The frequencies of occurrence of the pentaploid plants and the cytotypes involving a deficient chromosome were relatively low. While the diploid cytotype is restricted to fragile gravitational slopes and rocky areas which are poor in species and lack tall competitors, the polyploids occur widely in the grasslands, the roadsides or the forest-margins, closely associated with tall grasses and forbs such asMiscanthus sinensis. Based on these data, theE. chinense var.simplicifolium complex is divided into two distinct groups: the diploid cytotype and the polyploid cytotypes.     

Effects of above-ground plant species composition and diversity on the diversity of soil-borne microorganisms

A coupling of above-ground plant diversity and below-ground microbial diversity has been implied in studies dedicated to assessing the role of macrophyte diversity on the stability, resilience, and functioning of ecosystems. Indeed, above-ground plant communities have long been assumed to drive below-ground microbial diversity, but to date very little is known as to how plant species composition and diversity influence the community composition of micro-organisms in the soil. We examined this relationship in fields subjected to different above-ground biodiversity treatments and in field experiments designed to examine the influence of plant species on soil-borne microbial communities. Culture-independent strategies were applied to examine the role of wild or native plant species composition on bacterial diversity and community structure in bulk soil and in the rhizosphere. In comparing the influence of Cynoglossum officinale (hound's tongue) and Cirsium vulgare (spear thistle) on soil-borne bacterial communities, detectable differences in microbial community structure were confined to the rhizosphere. The colonisation of the rhizosphere of both plants was highly reproducible, and maintained throughout the growing season. In a separate experiment, effects of plant diversity on bacterial community profiles were also only observed for the rhizosphere. Rhizosphere soil from experimental plots with lower macrophyte diversity showed lower diversity, and bacterial diversity was generally lower in the rhizosphere than in bulk soil. These results demonstrate that the level of coupling between above-ground macrophyte communities and below-ground microbial communities is related to the tightness of the interactions involved. Although plant species composition and community structure appear to have little discernible effect on microbial communities inhabiting bulk soil, clear and reproducible changes in microbial community structure and diversity are observed in the rhizosphere. This revised version was published online in August 2006 with corrections to the Cover Date.     

Allelopathy and its coevolutionary implications between native and non‐native neighbors of invasive Cynara cardunculus L.

Invasive plants apply new selection pressures on neighbor plant species by different means including allelopathy. Recent evidence shows allelopathy functions as remarkably influential mediator for invaders to be successful in their invaded range. However, few studies have determined whether native and non‐native species co‐occurring with invaders have evolved tolerance to allelopathy. In this study, we conducted germination and growth experiments to evaluate whether co‐occurring native Juncus pallidus and non‐native Lolium rigidum species may evolve tolerance to the allelochemicals induced by Cyanara cardunculus in Australian agricultural fields. The test species were germinated and grown in pots filled with collected invaded and uninvaded rhizosphere soil of C. cardunculus with and without activated carbon (AC). Additionally, a separate experiment was done to differentiate the direct effects of AC on the test species. The soil properties showed invaded rhizosphere soils had higher total phenolic and lower pH compared with uninvaded soils. We found significant reduction of germination percentage and seedling growth in terms of above‐ and belowground biomass, and maximum plant height and root length of native in the invaded rhizosphere soil of C. cardunculus, but little effect on non‐native grass species. Even soil manipulated with AC showed no significant differences in the measured parameters of non‐native except aboveground biomass. Taken together, the results indicate allelochemicals induced by C. cardunculus exert more suppressive effects on native than non‐native linking the coevolved tolerance of those.     

Comparison of common cytotypesof Andropogon gerardii(Andropogoneae,Poaceae)

Many plant species contain populations with more than one polyploid cytotype, but little is known of the mechanisms maintaining several cytotypes in a population. Andropogon gerardii cytotypes were compared to evaluate different models of autopolyploid cytotype coexistence. The enneaploid (90 chromosome, 9x) cytotype was found to be larger and taller than the hexaploid (60 chromosome, 6x) cytotype. Seed production is significantly more efficient in hexaploids, but seed production per area was not significantly different. The two cytotypes are not exomorphologically separable in the field because of great plasticity in response to environmental variation and wide variation within each cytotype. These data suggest cytotypic variation is maintained by natural selection.     

Changes in microbial activity and composition in a pasture ecosystem exposed to elevated atmospheric carbon dioxide

Elevated atmospheric CO₂ increases aboveground plant growth and productivity. However, carbon dioxide-induced alterations in plant growth are also likely to affect belowground processes, including the composition of soil biota. We investigated the influence of increased atmospheric CO₂on bacterial numbers and activity, and on soil microbial community composition in a pasture ecosystem under Free-Air Carbon Dioxide Enrichment (FACE). Composition of the soil microbial communities, in rhizosphere and bulk soil, under two atmospheric CO₂ levels was evaluated by using phospholipid fatty acid analysis (PLFA), and total and respiring bacteria counts were determined by epifluorescence microscopy. While populations increased with elevated atmospheric CO₂ in bulk soil of white clover (Trifolium repens L.), a higher atmospheric CO₂ concentration did not affect total or metabolically active bacteria in bulk soil of perennial ryegrass (Lolium perenne L.). There was no effect of atmospheric CO₂ on total bacteria populations per gram of rhizosphere soil. The combined effect of elevated CO₂ on total root length of each species and the bacterial population in these rhizospheres, however, resulted in an 85% increase in total rhizosphere bacteria and a 170% increase in respiring rhizosphere bacteria for the two plant species, when assessed on a per unit land area basis. Differences in microbial community composition between rhizosphere and bulk soil were evident in samples from white clover, and these communities changed in response to CO₂ enrichment. Results of this study indicate that changes in soil microbial activity, numbers, and community composition are likely to occur under elevated atmospheric CO₂, but the extent of those changes depend on plant species and the distance that microbes are from the immediate vicinity of the plant root surface.     

施磷对干旱胁迫下箭竹根际土壤养分及微生物群落的影响

以箭竹及其根际土壤作为研究对象,采用两因素随机区组实验,设置2种水分处理（正常浇水和干旱胁迫）和2种施磷量处理（施磷和不施磷）,探究施磷对干旱胁迫下箭竹根际土壤养分及微生物群落结构和多样性的影响。结果表明：（1）干旱胁迫显著降低了箭竹根际土壤中微生物量碳、可溶性有机氮和有效磷的含量,虽对箭竹根际土壤微生物群落的多样性无显著影响,但显著降低了箭竹根际土壤中总PLFA（phospholipid fatty acid contents）的含量和真菌、细菌、革兰氏阳性菌与革兰氏阴性菌的PLFA含量以及革兰氏阳性菌/革兰氏阴性菌的PLFA比值,显著改变了箭竹根际土壤微生物群落结构,结果显著降低了箭竹的生物量。（2）施磷显著增加了受旱箭竹根际土壤中微生物量碳和有效磷的含量,虽大体上对受旱箭竹根际土壤微生物群落的多样性无显著影响,但显著增加了受旱箭竹根际土壤中总PLFA和真菌PLFA的含量,并在一定程度上增加了细菌、革兰氏阳性菌、革兰氏阴性菌和放线菌的PLFA含量以及革兰氏阳性菌/革兰氏阴性菌和真菌/细菌的PLFA比值,也在一定程度上改善了受旱箭竹根际土壤微生物群落结构,从而改善受旱箭竹的生长。（3）主成分分析表明,干旱对箭竹根际土壤微生物群落结构的影响显著,而施磷的影响不明显。（4）相关分析发现,箭竹根际土壤微生物群落结构与箭竹根际土壤微生物量碳、可溶性有机氮及箭竹生物量呈显著正相关。综上,干旱降低了箭竹根际土壤养分含量和微生物生物量,改变了箭竹根际土壤微生物群落结构,抑制了箭竹的生长;施磷能增加受旱箭竹根际土壤养分含量和微生物生物量,改善受旱箭竹根际土壤微生物群落结构,进而改善受旱箭竹的生长。