Subterranean Plant Research Articles

Preparation and Application of Self-adaptive Porous Polyethylene for Mulch Film

Porous polyethylene has emerged as a consequential constituent within the realm of infrared thermal management, owing to its commendable transmittance in the thermal infrared domain and noteworthy high scattering capabilities within the visible spectrum. In this study, we have fabricated porous polyethylene and conducted a comprehensive investigation into its adaptable emissivity alterations within the infrared range, while concurrently upholding a pronounced scattering proficiency in the visible band. Furthermore, we have proffered the prospective application of the prepared adaptive porous polyethylene in the context of mulch film. Empirical has unequivocally demonstrated that the utilization of adaptive porous polyethylene can effectively engender adaptive cooling and insulation modulation in the realm of subterranean plant growth, by harnessing its efficient performance across both the visible and thermal infrared spectra. Simultaneously, the material continually scatters visible light, thereby providing supplemental illumination to plant leaves and fruits in a retrograde manner. This breakthrough affords an efficacious and cost-effective energy-conserving apparatus in the domain of agricultural production.

Characterization of metabolite landscape distinguishes wild from cultivated Polygonati Rhizomes by UHPLC-Q-TOF-MS untargeted metabolomics

Rhizome, a modified subterranean plant stem, has been used in China for centuries as a Traditional Chinese Medicine (TCM). Polygonati Rhizome (PR) is a well-known species in the Rhizome family. Previous studies show that PR might be beneficial in the treatment of osteoporosis, cancer, diabetes, and many other diseases because of its properties such as antioxidant property. Thus cultivated PR strains were developed to fulfil the increasing demands. However, the metabolite profile differences between wild-type and cultivated PR remain largely unknown. Here, we performed unbiased and untargeted quantitative mass spectrometry-based metabolomics on 1 wild strain and 3 cultivated strains. A total of 1126 metabolites were identified on all 4 strains. Analyses of these data with unsupervised and supervised approaches identified common metabolites in all 4 strains as well as strain-specific metabolites. Next, we conducted a metabolomic-wide pairwise correlation analysis on metabolite abundance and discovered 577 significantly correlated metabolite-metabolite pairs by Pearson's correlation test. Importantly, KEGG enrichment analysis indicated that phenylpropanoids biosynthesis was the most differentially expressed pathway between cultivated and wild-type PR. By contrast, common metabolites on all 4 strains might suggest shared therapeutic targets. In summary, the systematic, untargeted metabolomics profiling of 4 PR strains and comprehensive data analyses provide invaluable resources to the understanding of the metabolite landscape and shed light on potential therapeutic applications for the treatment of diseases.

A Comparative Analysis of the Anatomy, Phenolic Profile, and Antioxidant Capacity of Tussilago farfara L. Vegetative Organs.

Tussilago farfara L., a perennial species, is a medicinal herb used in traditional medicine, mainly for the treatment of respiratory tract-related pathology. In traditional Chinese medicine, flower buds are preferred; in Europe, the leaves are used; and in some parts of India, the whole plant is utilized. This preferential usage of the plant organs might be based on differences in the chemical composition due to environmental conditions, along with preferred traditional and cultural approaches. In this article, the impact of pedoclimatic growth conditions on the morpho-anatomical development and phytochemical profile of the plant were studied on T. farfara in the vegetative state, collected from two different locations in the Romanian spontaneous flora, revealing significant variations. Furthermore, the antioxidant profile of the specific extracts from the aerial and subterranean plant parts is also in accordance with these discrepancies. The plant anatomy was assessed histologically by optical microscopy, while the analytical chemistry evaluation was based on LC/MS and spectral methods for the evaluation of the antioxidant and enzyme inhibitory activity. To our knowledge, this is the first comparative analysis contextually reporting on the histology, phenolic profile, antioxidant capacity, and geographical location of the vegetative form of T. farfara.

Beneficial worm allies warn plants of parasite attack below-ground and reduce above-ground herbivore preference and performance.

Antagonistic interactions among different functional guilds of nematodes have been recognized for quite some time, but the underlying explanatory mechanisms are unclear. We investigated responses of tomato (Solanum lycopersicum) to two functional guilds of nematodes-plant parasite (Meloidogyne javanica) and entomopathogens (Heterorhabditis bacteriophora, Steinernema feltiae below-ground, and S.carpocapsae)-as well as a leaf mining insect (Tuta absoluta) above-ground. Our results indicate that entomopathogenic nematodes (EPNs): (1) reduced root knot nematode (RKN) infestation below-ground, (2) reduced herbivore (T.absoluta) host preference and performance above-ground, and (3) induced overlapping plant defence responses by rapidly activating polyphenol oxidase and guaiacol peroxidase activity in roots, but simultaneously suppressing this activity in above-ground tissues. Concurrently, we investigated potential plant signalling mechanisms underlying these interactions using transcriptome analyses. We found that both entomopathogens and plant parasites triggered immune responses in plant roots with shared gene expression. Secondary metabolite transcripts induced in response to the two nematode functional guilds were generally overlapping and showed an analogous profile of regulation. Likewise, we show that EPNs modulate plant defence against RKN invasion, in part, by suppressing active expression of antioxidant enzymes. Inoculations of roots with EPN triggered an immune response in tomato via upregulated phenylpropanoid metabolism and synthesis of protease inhibitors in plant tissues, which may explain decreased egg laying and developmental performance exhibited by herbivores on EPN-inoculated plants. Furthermore, changes induced in the volatile organic compound-related transcriptome indicated that M.javanica and/or S.carpocapsae inoculation of plants triggered both direct and indirect defences. Our results support the hypothesis that plants "mistake" subterranean EPNs for parasites, and these otherwise beneficial worms activate a battery of plant defences associated with systemic acquired resistance and/or induced systemic resistance with concomitant antagonistic effects on temporally co-occurring subterranean plant pathogenic nematodes and terrestrial herbivores.

Consumption of cultivated subterranean plant organs by chimpanzees in a human-dominated landscape

Abstract Although chimpanzees (Pan troglodytes) are ripe fruit specialists, they sometimes consume other plant parts including subterranean organs like roots and tubers. Such plant parts, which include underground storage organs (USOs), have been found to play a key role in the diets of some chimpanzee populations as well as, potentially, our hominin ancestors. We report the confirmed consumption of subterranean plant organs of three species — sweet potatoes (Ipomoea batatas), yams (Dioscorea alata) and peanuts (Arachis hypogaea), as well as unconfirmed consumption of cassava (Manihot esculenta) — by chimpanzees in a human-dominated landscape in western Uganda. These observations point toward the dietary flexibility of chimpanzees inhabiting anthropogenic landscapes, though mechanisms of novel food acquisition, particularly for subterranean fruits and tubers, are not well understood. Dietary flexibility may help chimpanzees survive as natural forest resources disappear, but simultaneously may bring them into greater conflict with their human neighbours, thereby further imperilling them.

Causes of leaf reddening in subterranean clover cultivars

ABSTRACT Subterranean clover (Trifolium subterraneum L.) is an important legume in dryland hill pastures in New Zealand. In this environment plants adapt to low temperatures (<10°C) through a series of physiological mechanisms, such as the foliar biosynthesis of pigments, to protect vulnerable tissues. The biosynthesis of anthocyanins is one of the most important physiological responses for cold acclimation in plants. In this study we investigated anthocyanin concentration by accessing leaf reddening in 14 cultivars from three subspecies (yanninicum, brachycalycinum or subterraneum) during winter growth. The effect of anthocyanin production on spring herbage productivity was further quantified in the field and in the glasshouse. Leaf concentration of anthocyanins increased 10-fold as a consequence of cold exposure (mean daily air temperature was below ∼7°C) in red leaves compared with green leaves. There were large cultivar differences with yanninicum ssp. cultivars having the highest leaf reddening at >60%. Lowest values were observed in ‘Antas’ (brachycalycinum ssp.) and ‘Denmark’ (subterraneum spp.) at <20% of leaf reddening. Australian subterraneum ssp. cultivars had 13% higher leaf reddening values than Italian cultivars. Leaf reddening was a temporary, cold induced, anthocyanin response that did not affect subsequent subterranean clover plant growth.

&lt;p class="Body"&gt;&lt;strong&gt;&lt;em&gt;Rhizoglyphus &lt;/em&gt;&lt;/strong&gt;&lt;strong&gt;mites (Acari: Astigmata: Acaridae)&lt;em&gt; &lt;/em&gt;from Brazil, with complementary description of &lt;em&gt;Rhizoglyphus vicantus &lt;/em&gt;Manson&lt;/strong&gt;&lt;/p&gt;

Rhizoglyphus species are commonly found associated with subterranean plant organs, where they may lead to direct or indirect damages. The diversity of this genus in Brazil is poorly known and the most frequently mentioned species in the country is Rhizoglyphus echinopus (Fumouze &amp; Robin). However, this species appears on the A1 quarantine list for Brazil. The objective of the present work was to report the Rhizoglyphus species that have been collected in agricultural environments in Brazil. In this study, five species are reported: R. caladii Manson, R. columbianus Oudemans, R. robini Claparède, R. setosus Manson and R. vicantus Manson. Among these, four are new records for Brazil (R. caladii, R. columbianus, R. setosus and R. vicantus).

Morphological diversity and identification key for landraces of the Amerindian yam in central Amazon

Abstract: The objective of this work was to select an optimal set of morphological descriptors, in order to characterize the phenotipical diversity of Amerindian yam (Dioscorea trifida) landraces cultivated in the municipality of Caapiranga, in the central Amazon region of Brazil, and to develop a botanical identification key for them. A collection of 140 accessions and an experimental plot with a representative sample of 20 landraces were used to test 64 morphological descriptors for the aerial and subterranean plant parts. Forty-eight descriptors were selected, of which 13 were for tubers, 12 for stems, 14 for leaves, and 9 for inflorescences and seed. A cluster analysis based on the morphological data showed the formation of two landrace groups with greater similarity: white and purple pulp tubers. The results provide tools for in situ and ex situ conservation and for plant breeding programs, considering the importance of maintaining and recognizing the value of Ameridian yam as an important native genetic resource for food security in the region.

The buried medieval pasture of Onoldswil (Niederdorf BL, Switzerland, ad 1295): an example of a well preserved palaeobiocoenosis

In the late spring of the year ad 1295 a landslide devastated the village of Onoldswil in the Swiss Jura mountains. During recent construction work, a small area of the original land surface was unearthed. The 5 m of compacted clay deposited by the landslide had caused the complete exclusion of oxygen and underneath it the excavators came upon mosses, blades of grasses and other plants that were still green. Below the vegetation cover the humus horizon with subterranean plant parts appeared. Samples were taken for plant macro- and microfossil and geoarchaeological analyses. This offered the rare opportunity to study the vegetation and the topsoil of a small area of land preserved in situ as an autochthonous palaeobiocoenosis, the preserved original combination of the plant community which grew there. Grassland taxa dominated the pollen and macrofossil spectra. Compacted zones within the humus horizon, the plant taxa composition and the presence of spores of coprophilous fungi showed that this place had once been a nutrient-rich pasture. Grazing animals had favoured the spread of juniper. Manuring seems to have taken place. The slopes of the surrounding mountains had been largely cleared of woodland, which may have been the cause of the landslide. The disaster probably happened in late spring, because entire fruiting capitula of Taraxacum officinale (dandelion) were found. Landslides are catastrophic events, destroying the soils and everything that lives in and on them on their way downhill. In places, however, they can also blanket the original land surface and its vegetation and create an archive of ancient life.

Plant Spacing Implications for Grafted Grapevine I. Soil Characteristics, Root Growth, Dry Matter Partitioning, Dry Matter Composition and Soil Utilisation

Six plant spacings (3 x 3 m, 3 x 1,5 m, 2 x 2 m, 2 x 1 m, 1 x 1 m, 1 x 0,5 m) were evaluated for their effect on aboveground and subterranean growth, dry matter partitioning and dry matter composition of different plant parts of vertically trellised Vitis vinifera L. cv. Pinot noir vines grafted onto rootstock 99 Richter. The vines were pruned to six buds/m2 soil surface area and supplementary irrigated just after pea berry size and veraison stages. Root distribution was studied by using the profile wall method and by excavating the whole plant. Apparently higher bulk densities occurred in the top soil layers of closer spacings. In the case of fine ( < 0,5 mm), extension (0,5 • 2 mm) and permanent (2 - 5 mm) roots, closer spaced vines significantly compensated in terms of root number per profile wall area. Higher root densities occurred with closer spacing. Aboveground and subterranean growth of the closerspaced vines were reduced; a distinction between in-row spacings of 1,5 m and wider and those 1 m and narrower occurred. Aboveground and subterranean growth were positively related. The angle of root penetration and size of the root system increased with wider spacing. The spread of the root system was apparently not affected by either inter-row or in-row spacing. The majority of roots were located within the allocated in-row distance. Cane and root mass and total vine dry mass per m2 soil surface indicated optimum utilisation of soil volume for medium-spaced vines (2 x 2 m, 2 x 1 m). Evidently higher starch concentrations occurred in the cordons, trunks and roots of widerspaced vines. Roots contained the highest starch concentrations, followed by the trunk, cordon, canes and rootstock trunk. Starch contents of aboveground and subterranean plant parts were similar. The ratio of aboveground:subterranean starch content was, however, lower for closely spaced vines.

Cultivation Versus Molecular Analysis of Banana (Musa sp.) Shoot-Tip Tissue Reveals Enormous Diversity of Normally Uncultivable Endophytic Bacteria.

The interior of plants constitutes a unique environment for microorganisms with various organisms inhabiting as endophytes. Unlike subterranean plant parts, aboveground parts are relatively less explored for endophytic microbial diversity. We employed a combination of cultivation and molecular approaches to study the endophytic bacterial diversity in banana shoot-tips. Cultivable bacteria from 20 sucker shoot-tips of cv. Grand Naine included 37 strains under 16 genera and three phyla (Proteobacteria, Actinobacteria, Firmicutes). 16S rRNA gene-ribotyping approach on 799f and 1492r PCR-amplicons to avoid plant organelle sequences was ineffective showing limited bacterial diversity. 16S rRNA metagene profiling targeting the V3-V4 hypervariable region after filtering out the chloroplast (74.2%), mitochondrial (22.9%), and unknown sequences (1.1%) revealed enormous bacterial diversity. Proteobacteria formed the predominant phylum (64%) succeeded by Firmicutes (12.1%), Actinobacteria (9.5%), Bacteroidetes (6.4%), Planctomycetes, Cyanobacteria, and minor shares (<1%) of 14 phyla including several candidate phyla besides the domain Euryarchaeota (0.2%). Microbiome analysis of single shoot-tips through 16S rRNA V3 region profiling showed similar taxonomic richness and diversity and was less affected by plant sequence interferences. DNA extraction kit ominously influenced the phylogenetic diversity. The study has revealed vast diversity of normally uncultivable endophytic bacteria prevailing in banana shoot-tips (20 phyla, 46 classes) with about 2.6% of the deciphered 269 genera and 1.5% of the 656 observed species from the same source of shoot-tips attained through cultivation. The predominant genera included several agriculturally important bacteria. The study reveals an immense ecosystem of endophytic bacteria in banana shoot tissues endorsing the earlier documentation of intracellular "Cytobacts" and "Peribacts" with possible roles in plant holobiome and hologenome.

Do foraging methods in winter affect morphology during growth in juvenile snow geese?

Physical exertion during growth can affect ultimate size and density of skeletal structures. Such changes from different exercise regimes may explain morphological differences between groups, such as those exhibited by lesser snow geese (Chen caerulescens caerulescens; hereafter snow geese) foraging in southwest Louisiana. In rice‐prairie habitats (hereafter rice‐prairies), snow geese bite off or graze aboveground vegetation, whereas they dig or grub for subterranean plant parts in adjacent coastal marshes. Grubbing involves considerably more muscular exertion than does grazing. Thus, we hypothesized that rates of bone formation and growth would be lower for juveniles wintering in rice‐prairies than those in coastal marshes, resulting in smaller bill and skull features at adulthood. First, we tested this exertion hypothesis by measuring bills, skulls, and associated musculature from arrival to departure (November–February) in both habitats in southwest Louisiana, using both banded birds and collected specimens. Second, we used the morphological data to test an alternative hypothesis, which states that smaller bill dimensions in rice‐prairies evolved because of hybridization with Ross's geese (C. rossii). Under the exertion hypothesis, we predicted that bill and skull bones of juveniles would grow at different rates between habitats. However, we found that bill and skull bones of juveniles grew similarly between habitats, thus failing to support the exertion hypothesis. Morphometrics were more likely to differ by sex or change with sampling date than to differ by habitat. We predicted that significant, consistent skewness toward smaller birds could indicate hybridization with Ross's geese, but no skewness was observed in our morphological data, which fails to support the hybridization hypothesis. Further research is needed to clarify whether snow geese wintering in Louisiana represent a single polymorphic population that segregates into individually preferred habitats, which we believe at present to be more likely as an explanation than two ecologically and spatially distinct morphotypes.

Passive heat treatment of sweet basil crops suppressesPeronospora belbahriidowny mildew

Sweet basil (Ocimum basilicum) is an annual herb crop grown in polyethylene-covered structures in Israel. It is Israel's leading herb crop, grown in warm regions of the country. Downy mildew (caused by Peronospora belbahrii) is a severe disease in Israel and in many other crop-growing regions worldwide. Experiments were carried out to identify potential climate-management techniques for suppression of this disease on basil in non-heated greenhouses. Disease severity was evaluated under commercial-like conditions in three experiments, with 8–10 walk-in tunnels at each location. Pathogen inoculum was introduced into all walk-in tunnels. Regression analysis was performed between the disease values and air temperature, relative humidity (RH) and soil temperature. Downy mildew severity was negatively related to high (>25°C) air temperature, RH in the range of 65–85% and high (>21°C) soil temperature. The increase in air temperature did not result in a significant increase in leaf temperature; canopy surface median temperatures only reached 30°C. Symptomless plants from relatively warmer tunnels (peak temperatures of 45–48°C) that were transferred to conditions that promote downy mildew (22 ± 2°C, RH > 95%) became severely diseased, showing sporulation of P. belbahrii, suggesting that infection occurred but at the high temperatures symptom expression/tissue colonisation was suppressed. Pot experiments in which aerial and subterranean plant organs were differentially heated revealed that treating the roots with a high temperature (26–31°C), similar to the soil temperatures in the warmer greenhouses, while maintaining the upper plant parts at ambient temperature (20°C), suppresses canopy downy mildew. The effect lasted for 1–2 weeks after the plants were removed from the heated soil treatments and maintained under optimal conditions for pathogen development. Furthermore, oospores were found in the symptomatic leaves. Oospores are minimally affected by high temperature, and therefore the high temperature presumably did not affect pathogen survival. In conclusion, the effect of high greenhouse temperature on basil downy mildew may not result from a direct negative effect of high temperature on the pathogen but from an indirect high-temperature effect on the host, rendering it less susceptible to pathogen development.

A new model for the pathozone of the take‐all pathogen, Gaeumannomyces graminis var. tritici

AbstractThe pathozone (volume of soil surrounding subterranean plant organs within which a propagule must occur if it is to have any chance of infecting the organ) is usually described by statistical models lacking biological meaning. For this reason, pathozone results might be difficult to interpret and the estimated parameters cannot be re‐used in other studies. We developed a model with parameters reflecting life‐history traits concerning primary infections of soilborne pathogens. The model was then fitted to experimental data obtained from eight isolates of Gaeumannomyces graminis var. tritici, causal agent of take‐all disease of wheat. Our model provided not only a mechanistic description for the pathozone dynamics, but also a better fit to the data than four other models published in the literature. Although the isolates displayed phenotypic variability in terms of pathozone dynamics, these differences did not map onto the G1 and G2 genetic subgroups known to occur in Ggt populations.

Species Substitution in Medicinal Roots and Possible Implications for Toxicity of Herbal Remedies in Morocco

Species Substitution in Medicinal Roots and Possible Implications for Toxicity of Herbal Remedies in Morocco. Herbal medicine is an integral part of health care in Morocco and is widely used by Moroccans. However, the efficacy and safety of traditional plant-based medicine in Morocco is threatened by insufficient knowledge about practices of adulteration and substitution. These issues are of particular importance when subterranean plant parts are employed. A combination of qualitative and quantitative methods was used to identify where and why confusion (accidental substitution) and intentional substitution occurs in root-based medicines sold in Marrakech. Additionally we examined local perceptions of the toxicological risks posed by substitution. We recorded a total of 20 species (34 unique cases) of roots for which substitution or confusion was reported by either herbalists or collectors. Substitution or confusion occurred in 54.6 % of the 33 most commonly sold medicinal roots, with herbalists reporting substitution in more species than collectors. Collectors and herbalists cited poor availability of roots (in part due to overexploitation of wild resources), high demand, high prices, and lack of knowledge as factors driving substitution and confusion. Roots for which substitution was reported were significantly more difficult for herbalists to identify. Moreover, profit was higher for roots for which intentional substitution was reported. Despite the detailed knowledge held by many herbalists and a long tradition of use of herbal medicine in Morocco, doctors and pharmacists had dismissive attitudes towards traditional medicine and expressed concern about both efficacy and safety of medicinal plant use. Given the high rates of substitution and confusion documented by this study, there is an urgent need for appropriate regulation of herbal remedies in Morocco, a conclusion embraced by herbalists and Western-trained medical practitioners alike.

The restless plant

The restless plant

Constitutive and induced subterranean plant volatiles attract both entomopathogenic and plant parasitic nematodes

Summary 1. Indirect plant defences are well documented for the above‐ground constituents of plants. Although less investigated to date, below‐ground defences that mediate multitrophic interactions are equally important. Entomopathogenic nematodes (Steinernema diaprepesi) are attracted to herbivore‐induced volatiles from Swingle var. (Citrus paradisi×Poncirus trifoliata) when fed upon by root weevil, Diaprepes abbreviatus. 2. We examined the extent to which below‐ground volatiles modify behaviour of nematode species representing various foraging strategies (cruisers versus ambushers) and trophic levels (plant parasites versus entomopathogens). We compared attraction to volatiles of weevil‐infested and non‐infested roots from Swingle citrus rootstock and a parent line of the Swingle hybrid, Poncirus trifoliata (Pt). 3. Swingle weevil‐infested roots attracted more nematodes than non‐infested roots irrespective of nematode foraging strategy and trophic status. The parental line, Pt, attracted all nematode species irrespective of insect herbivory. 4. Dynamic in situ collection and GC–MS analysis of volatiles from soil revealed that Pt roots release attracting cues constitutively. A different non‐hybrid citrus species (sour orange, Citrus aurantium) released nematode attracting cues only in response to larval feeding, similar to responses found in Swingle. Volatile collections from above‐ and below‐ground portions of citrus plants revealed that above‐ground feeding by weevils does not induce production of nematode attracting cues analogous to that induced by root damage, nor does damage by larvae below‐ground induce a similar volatile above ground. 5. Synthesis. Our results suggest that release of nematode attractants by citrus roots occurs broadly and can be constant or herbivore‐induced. The major constituent of this indirect defence is produced by roots and not shoots and in response to below‐ground, but not above‐ground herbivory. Our findings suggest that this cue acts on nematode species broadly, attracting entomopathogenic nematodes that exhibit various foraging strategies. Unexpectedly, we also found that this cue attracts a plant parasitic nematode species. It appears, thus, that release of nematode attracting cues by citrus plants can cause ecological costs. The plants, however, appear to counteract against these costs, because constitutive release was found only in a cultivar that is resistant to phytopathogenic nematodes, while herbivore‐induced release occurred in lines susceptible to pathogenic nematode species.

Intra- and interspecific variation in home-range size in sympatric tuco-tucos, Ctenomys australis and C. talarum

Despite the fundamental nature of the home range to the biology of a species, aspects of its size, shape, and structure are not well defined in certain groups, such as subterranean rodents. These rodents, characterized by limited individual mobility and a patchy distribution of local populations, generally defend multipurpose territories in which breeding and foraging take place, increasing the chances for trade-offs among factors of habitat quality. The present study assessed the home-range size and shape of 2 species of tuco-tucos, Ctenomys australis (300–600 g) and C. talarum (100–180 g), using radiotelemetry in an area where they occur in sympatry, and explored the factors that could influence space use in these subterranean rodents. Home-range size (95% adaptive kernel) of C. australis (1,282.22 6 1,014.83 m 2 ) was ,19-fold larger than that of C. talarum (66.69 6 22.34 m 2 ). The area covered daily by C. australis represented only about 9% of the total home-range size estimated by radiotelemetry in this study and was almost twice as large as that of C. talarum, but the area covered by the latter species represented an average of 35% of its total home-range size. Total aerial and subterranean plant biomass, plant cover, and soil hardness were significantly higher in the habitat occupied by C. talarum. Contrary to expectation, body size was not the predominant factor explaining intra- and interspecific variation in home-range size. We discuss how variation in food availability in space and time and differences in the intensity of polygyny could be more important factors shaping home-range size in this genus of subterranean rodents. DOI: 10.1644/10-MAMM-A-057.1.

Variation in saponin content during the growing season of spotted medic [Medicago arabica (L.) Huds.

Spotted medic [Medicago arabica (L.) Huds.] is a minor forage species containing saponins which are reported to be biologically active. This study assessed the concentration and composition pattern of spotted medic saponins during the growing season and at senescence. The pattern of saponins was based on identification and quantification of their constituent sapogenins. At senescence, individual saponin concentrations of aerial and subterranean plant organs were also determined. Leaf total saponin content did not vary during the growing season and decreased remarkably at senescence. Seven sapogenins were identified and quantified during the season, bayogenin and hederagenin being the most abundant ones throughout. Total saponin content varied among plant organs at senescence, with the highest concentration in roots. A variable number of saponins from one (in seeds) to 19 (in leaves) were quantified. A clear relationship between leaf concentrations of sapogenins and those of their derivative saponins was revealed by correlation analysis. The species displayed a sapogenins/saponins pattern markedly different from those of other perennial or annual Medicago species. Saponins of queretaroic acid and 2β-hydroxy queretaroic acid had no precedent in the Leguminosae. The high concentration of biologically active hederagenin suggested further assessment of possible effects on feeding animals.

Efeito de extratos aquosos de estruturas de grama-seda no desenvolvimento inicial de plântulas de arroz, milho e trigo

Objetivou-se verificar os efeitos de extratos aquosos de estruturas de grama-seda (Cynodon dactylon (L.) Pers) e de exsudatos radiculares presentes no solo no qual a planta se desenvolveu, sobre a germinação e o crescimento inicial de arroz, trigo e milho. O extrato aquoso das estruturas da parte aérea, subterrâneas e da planta inteira, assim como do estolão, da folha + colmo, estolão + folha + colmo, rizoma, raiz e de rizoma + raiz de grama-seda foi elaborado a partir de 100 g L-1 de material seco. Foram avaliados a protrusão da radícula e os crescimentos da radícula e da plúmula de cada espécie. A inibição ou o estímulo do desenvolvimento inicial de plântulas foi dependente da espécie avaliada e da estrutura vegetal empregada na elaboração do extrato. A protrusão da radícula foi mais inibida que os crescimentos da radícula e da plúmula. O estímulo do desenvolvimento da radícula e da plúmula foi mais evidente quando o extrato foi elaborado a partir das estruturas do sistema radicular, da parte aérea e da planta inteira que de estruturas individualizadas de grama-seda. De modo geral, o arroz e o milho foram mais inibidos por extratos elaborados a partir da parte aérea e subterrânea, respectivamente. Para o trigo, a inibição ou o estímulo foi dependente da variável analisada. O desenvolvimento da radícula e da plúmula de arroz, milho e trigo foi estimulado por extrato elaborado a partir da planta inteira. O extrato produzido a partir da fração argila + silte estimulou o desenvolvimento da radícula do milho e da plúmula do trigo.