MORPHOMETRIC VARIATIONS OF FIVE TIDAL MARSH HALOPHYTES ALONG ENVIRONMENTAL GRADIENTS

Morphological characteristics of Deschampsia cespitosa, Grindelia integrifolia, Distichlis spicata, Jaumea carnosa, and Salicornia virginica varied significantly along transects between the upper and lower portions of an Oregon salt marsh. Plant height, height of the flowering shoot, leaf number and width, internode length, branching, and stem diameter varied with position in the marsh. Anatomical differences in stem structure were also obvious. Lignification of vascular bundles of D. spicata, the amount of secondary xylem in G. integrifolia, and vascular bundle size in J. carnosa were greatest in the upper marsh zone. The quantity of aerenchymatous tissue in S. virginica was greatest at the lower, wetter end of the transect. Reproductive effort was greatest at the upper distributional limit of G. integrifolia and D. spicata while greatest in J. carnosa at its lower limit. Soil moisture and soil chemical data were collected to relate morphometric variation to environmental parameters. Differences in plant structure may have application as an aid in determining wetland boundaries.     

Influence of Soil Moisture on Soil Solution Chemistry and Concentrations of Minerals in the Calcicoles Phleum phleoides and Veronica spicata Grown on a Limestone Soil

Veronica spicata and Phleum phleoides are calcicole plants,mainly occurring on neutral or alkaline soil. An experimentof 16 weeks duration was performed in a glasshouse with theobjective of elucidating the influence of soil moisture levelon soil solution chemistry, and biomass concentrations and uptakeof mineral nutrients by the plants. Seven levels of moisture,corresponding to 35–85% of the water holding capacity(WHC) of the soil, were tested. Soil solution HCO₃, P and Mnconcentrations, and pH, increased, whereas Ca, Mg and Zn concentrationsdecreased, with increasing soil moisture. Concentrations ofK were highest at 50–70% WHC. Concentrations and amountsof P, Zn and Mn in the two species were usually related to soilsolution concentrations; these are elements with low solubilityand availability in calcareous soils. Concentrations of nutrientsin biomass were more influenced by soil moisture in V. spicatathan inP. phleoides . This indicates that P. phleoides is morecapable of controlling its uptake of mineral nutrients, whereasV. spicata is sensitive to variations in soil moisture. It isconcluded that variation in soil moisture regime may greatlyinfluence concentrations of mineral nutrients in calcareoussoil solutions and their uptake by plants. Species able to utilizethese solubility fluctuations may have an advantage in competitionfor nutrients. Variation in soil moisture content might evenbe a prerequisite for adequate acquisition of mineral nutrientsand growth of plants on limestone soils, thereby influencingthe field distribution of native plants among habitats. Copyright1999 Annals of Botany Company Calcareous, calcicole, concentration, mineral, moisture, nutrient, Phleum phleoides, soil, soil solution, uptake, Veronica spicata, water.     

Root and rhizome distribution as an indicator of upper salt marsh wetland limits

Four wetland plant species, Deschampsia cespitosa, Distichlis spicata, Grindelia integrifolia, and Salicornia virginica, were tested to determine the effect of soil moisture on the vertical distribution of roots and rhizomes. In an 8-month greenhouse experiment involving plants grown from seeds and rhizomes the occurrence of more than 65% of the root and rhizome mass in the upper 10 cm of soil was indicative of saturated conditions. Roots and rhizomes were more evenly distributed under field capacity and low moisture conditions. The percent of total root and rhizome biomass in the upper 10 cm of a 35 cm core may be useful in determining whether or not a plant is experiencing saturated soil conditions, a criterion often used for defining wetlands. Limited field studies support the conclusion of the greenhouse study.     

The Dry Storage of Citrus Seeds

The survival of seeds of lemon (Citrus limon L.), lime [C. arantifolia(Christm.) Swing.] and sour orange (C. aurantium L.) was examinedunder a wide range of constant moisture contents and temperatures.Seed longevity was increased by decreasing the moisture contentand temperature of the storage environment. Maximum viabilitywas maintained in the combination of storage conditions includingthe lowest moisture content (5 per cent) and lowest temperature(–20 °C) investigated. The practicality of dry storageof citrus seed for genetic conservation is discussed. Citrus limon L., lemon, Citrus aurantifolia (Christm.), Swing, lime, Citrus aurantium L., sour orange, dry storage, moisture content, temperature, seed viability, seed longevity     

Studies with Liatris spicata Willd. 2. Effects of Photoperiod on Stem Extension, Flowering and Gibberellin Content

Flower formation in Liatris spicata Willd. was not affectedby photoperiodic treatments, but long days (16 h) had a pronouncedeffect on elongation of the flowering stem. An illuminance of2 Ix was sufficient to produce near maximal elongation. Long days caused a decrease in endogenous gibberellins in thetips of rapidly elongating stems and decreased the number offlowering stems per corm. Liatris spicata, elongation, flowering, gibberellin, light, photoperiod     

Response Breadths on Environmental Gradients of Germination and Seedling Growth in Two Dominant Forest Tree Species of Central Himalaya

The responses of Pimis roxburghii (chir pine), an early successionalspecies, andQuercus leucotrichophora(banj oak), a late successionalspecies were compared in terms of seed germination and seedlinggrowth. Seed germination was observed on single-factor gradientsof temperature, water stress, seed desiccation and light, andseedling growth on gradients of shade and soil moisture. Thesuppression of germination caused by continuous dark and far-redwas greater in Pinus than in Quercus. Pinus seed germinationshowed wider response breadth on gradients of water stress andseed desiccation, and narrower response breadth on the gradientof light quality, compared withQuercus. In terms of seedlinggrowth, the response breadth of Pinus was wider on the gradientof soil moisture and narrower on the gradient of shade comparedwith Quercus. Under higher soil moisture stress, the seedlingsof both species attained similar heights, butQuercus seedlingsachieved higher dry weights, a higher root: shoot ratio andlower leaf weight ratio than Pinus.     

Effects of Environmental Factors on Germination and Seedling Growth in Quercus floribunda and Cupressus torulosa, Tree Species of Central Himalaya

Quercus floribunda Lindl. (tilonj oak), a late successionalspecies, and Cupressus torulosa D. Don. (surai), an early successionalspecies, were compared in terms of seed germination and seedlinggrowth. In Petri dish germination tests in which light quality,temperature and osmotic water stress were varied, the germinationof both species was reduced by continuous dark or far-red lightand by osmotic water stress. These effects were greater on thegermination of surai than on that of tilonj oak. The growthof seedlings in soil was measured over a twelve-month periodduring which different levels of shading and different wateringregimes were applied. Surai was less affected than tilonj oakby reduced soil moisture, but the effect of deep shade treatmentswas greater on surai than with tilonj oak. At higher soil moisturestress seedlings of surai attained greater height then tilonjoak, but the latter achieved higher dry weight and a higherroot: shoot and lower leaf-weight ratio. Quercus floribunda Lindl. (tilonj oak), Cupressus torulosa D. Don. (surai), seed germination, seedling growth, environmental factors, regeneration     

Seasonal variations in plant nitrogen relations and photosynthesis along a grassland to shrubland gradient in Owens Valley, California

Community composition in semi-arid ecosystems has largely been explained by water availability; however, nitrogen is a common limiting nutrient, and may be an important control on plant function and carbon uptake. We investigated nitrogen relations and photosynthesis of several dominant species at shallow groundwater sites in Owens Valley, California. We measured soil nitrogen (N) availability, leaf N and isotopes, water isotopes, and gas exchange of dominant shrub species Atriplex torreyi and Ericameria nauseosa and grass species Distichlis spicata throughout the summer season in three sites that had similar watertable depths, but that varied in community composition and N availability. Surface soil inorganic N was greatest at the grassland site and declined from June to September at all sites. Leaf N declined throughout the season in all species, and was correlated with soil inorganic N. Photosynthesis of A. torreyi remained relatively constant throughout the season. In contrast, D. spicata and E. nauseosa experienced seasonal declines in photosynthesis at sites with greater inorganic N availability. Leaf N was significantly correlated with photosynthesis in D. spicata across all sites and measurement periods. Controls on N cycling are likely to be an important determinant of photosynthesis of D. spicata in this region.     

Heterogeneity in spatial P-distribution and foraging capability by Zea mays: effects of patch size and barriers to restrict root proliferation within a patch

• Background and Aims Localized proliferation of rootsin nutrient-enriched patches seems to be an adaptive responsein many plants, but its function is still debatable. To understandthe efficiency and limitation of foraging behaviour, the impactof patch size and the presence or absence of a barrier to rootproliferation within phosphorus (P)-enriched patches was examined. • Methods In pots filled with P-poor soil, six treatmentsof heterogeneous P supply were prepared: three patch sizes withor without a root barrier between patches. In addition, a homogeneousP supply treatment was also prepared. Irrespective of thesetreatments, each pot received the same total amount of P. Maize(Zea mays) was grown in each pot for 45 d in a greenhouse. • Key Results P content and biomass were greatest in plantsgrown in the largest patch due to successful root proliferation,and were higher in the presence of a root barrier. Interestingly,plants preferentially developed adventitious nodal roots projectingfrom the stem into the P-enriched soil, particularly in thelargest patch with a root barrier. Removal of the barrier reducedthe P-uptake capacity per unit root surface area or volume inP-enriched patches, revealing that the P-uptake capacity perroot can be suppressed even in P-rich soil if other portionson the root axis encounter P-poor conditions. • Conclusions The results suggest that the efficiency ofroot morphological plasticity is largely determined by the sizeof the P-enriched patch. Furthermore, the results imply a novelaspect of P-uptake physiology that roots in heterogeneous Pcannot demonstrate their potential capacity, as would be observedin roots encountering P continuously; this effect is probablymediated by an internal root factor.     

Comparison of Distichlis spicata and Suaeda aegyptiaca in response to water salinity: Candidate halophytic species for saline soils remediation

Distichlis spicata and Suaeda aegyptiaca are two potential halophytic plant species for bioremediation of salt degraded soils, and development of saline agriculture. The physiological responses of the species to different levels of salinity (EC 0, 12, 24, 36, and 48 dS/m) in a controlled environment experiment were studied. Both species showed a high level of tolerance to elevated concentrations of salt in the irrigation water. The shoot fresh and dry weights in S. aegyptiaca increased till 36 dS/m and were sustained under 48 dS/m while in D. spicata, both parameters decreased as salinity increased. Glycine betaine accumulation did not change in D. spicata with increasing salinity, whereas proline content revealed a marked increase of 7.13 fold in 48 dS/m salinity compared to the control, which showed its critical osmoprotection role in the plant. In S. aegyptiaca, both osmolytes content significantly increased at high salinity levels (36 and 48 dS/m) up to 3.22 and 2.0 folds, respectively. Overall, S. aegyptiaca had a better potential of Na⁺ phytoremediation, and tolerated higher salinity compared to D. spicata. In contrast, the vigorous root and rhizome growth in D. spicata made it a proper solution for protecting the soils against further erosion under saline conditions.     

Reproductive Isolation in a Native Population of Petunia sensu Jussieu (Solanaceae)

Reproductive isolation was studied in four syntopic speciesof Petunia sensu Jussieu (Solanaceae) at a site in Rio Grandedo Sul State, Brazil. Reciprocal artificial crossing experimentsconfirmed that a genetic barrier exists between Petunia(P. axillarisand P. integrifolia) andCalibrachoa (C. parviflora and C. heterophylla),and also between C. parviflora andC. heterophylla . Petuniaaxillaris(white, nocturnally scented flower) is geneticallycompatible with the syntopic and allotopic P. integrifolia(coloured,unscented flower). Reproductive isolation appears to be maintainedby the two species having different pollinators: nocturnallyactive hawkmoths (Manduca contracta andM. diffissa subsp. petuniae)pollinate P. axillaris while a diurnally active bee (Hexanthedasp.) pollinates P. integrifolia. Flowers of P. integrifoliaexhibit diurnal opening and closing movements synchronous withthe activity period of the bee. Other than a probable nectarrobber (a carpenter bee, Xylocopa augusti), no insect visitedflowers of P. axillaris in the day. Amounts of floral nectarin P. axillaris and P. integrifolia were within the range ofhawkmoth- and bee-pollinated flowers, respectively. Reproductiveisolating mechanisms in the genus Petunia sensu Jussieu arediscussed. Copyright 2001 Annals of Botany Company Calibrachoa, hawkmoth, Petunia, Petunia axillaris, Petunia integrifolia, pollinator, reproductive isolation, Solanaceae     

新疆麦田主要蚜虫的生态位

利用生态位理论,对新疆塔城、伊犁两地区麦田的麦双尾蚜Diuraphis noxia (Mordvilko)、麦二叉蚜Shizaphis graminum (Rondani)、麦长管蚜Sitobion avenae (F.)和禾谷缢管蚜Rhopalosiphum padi (L.)等4种麦蚜生态位宽度和重叠度进行了估测和分析。在塔城麦田麦双尾蚜时间生态位宽度最大,麦双尾蚜和麦二叉蚜时间生态位重叠最大,竞争激烈。伊犁麦田禾谷缢管蚜时间生态位宽度最大,麦二叉蚜在空间生态位和时 空二维生态位上均占有明显的优势,麦长管蚜和麦双尾蚜的时间生态位重叠最大,麦长管蚜和麦二叉蚜在空间生态位和时 空生态位重叠最大。     

Water Use Efficiency and Biomass Partitioning of Three Different Miscanthus Genotypes with Limited and Unlimited Water Supply

Miscanthus species, which are C₄perennial grasses, have a highbiomass potential but yields at many sites in Europe can belimited by insufficient water supply and plant survival is endangeredunder extreme summer drought. A pot experiment was conductedto measure the influence of reduced water supply on the wateruse efficiency (WUE) and biomass partitioning of three Miscanthusgenotypes (M. x giganteus, M. sacchariflorus, and a M. sinensishybrid) in a controlled environment. The experiment consistedof three phases (phase 1 = 0–20 d; phase 2 = 21–39d; phase 3 = 40–54 d) punctuated by destructive harvests.In phase 1, soil moisture was non-limiting. In the second andthird phases, lowered soil moisture contents induced water deficits.Air vapour pressure deficit (VPD) was 0.49 ± 0.05 kPa.Water deficits caused leaf senescence in M. x giganteus andM. sacchariflorus, but not in the M. sinensis hybrid. Greenleaf conductances were lowest in M. sinensis under water deficit,indicating stomatal regulation. Water use efficiency for wholeplants of each genotype ranged from 11.5 to 14.2 g dry matter(DM) kg^-1H₂O but did not differ significantly between genotypesor water treatments under the conditions of this experiment.However, differences in dry matter partitioning to the shoot(the harvestable component) resulted in genotypic differencesin WUE, calculated on a harvestable dry matter basis, whichranged from 4.1 g DM kg^-1H₂O for M. sacchariflorus to 2.2 gDM kg^-1H₂O for M. x giganteus. Copyright 2000 Annals of BotanyCompany Miscanthus sinensis, Miscanthus sacchariflorus, Miscanthus x giganteus, water use efficiency, biomass, C₄plants, drought     

Seasonal Fluctuations of Soil and Tissue Populations of Ditylenchus dipsaci and Aphelenchoides ritzemabosi in Alfalfa

Population dynamics of A. ritzemabosi and D. dipsaci were studied in two alfalfa fields in Wyoming. Symptomatic stem-bud tissue and root-zone soil from alfalfa plants exhibiting symptoms of D. dipsaci infection were collected at intervals of 3 to 4 weeks. Both nematodes were extracted from stem tissue with the Baermann funnel method and from soil with the sieving and Baermann funnel method. Soil moisture and soil temperature at 5 cm accounted for 64.8% and 61.0%, respectively, of the variability in numbers of both nematodes in soil at the Big Horn field. Also at the Big Horn field, A. ritzemabosi was found in soil on only three of the 14 collection dates, whereas D. dipsaci was found in soil on 12 dates. Aphelenchoides ritzemabosi was found in stem tissue samples on 9 of the 14 sampling dates whereas D. dipsaci was found on all dates. Populations of both nematodes in stem tissue peaked in October, and soil populations of both peaked in January, when soil moisture was greatest. Numbers of D. dipsaci in stem tissue were related to mean air temperature 3 weeks prior to tissue collection, while none of the climatic factors measured were associated with numbers of A. ritzemabosi. At the Dayton field, soil moisture plus soil temperature at 5 cm accounted for 98.2% and 91.4% of the variability in the soil populations of A. ritzemabosi and D. dipsaci, respectively. Aphelenchoides ritzemabosi was extracted from soil at two of the five collection dates, compared to extraction of D. dipsaci at three dates. Aphelenchoides ritzemabosi was collected from stem tissue at six of the seven sampling dates while D. dipsaci was found at all sampling dates. The only environmental factor that was associated with an increase in the numbers of both nematodes in alfalfa stem tissue was total precipitation 1 week prior to sampling, and this occurred only at the Dayton field. Numbers of A. ritzemabosi in stem tissue appeared to be not affected by any of the environmental factors studied, while numbers of D. dipsaci in stem tissue were associated with cumulative monthly precipitation, snow cover at time of sampling, and the mean weekly temperature 3 weeks prior to sampling. Harvesting alfalfa reduced the numbers of A. ritzemabosi at the Big Horn field and both nematodes at the Dayton field.     

Role of Legumes in Release of Successionally Arrested Grasslands in the Central Hills of Sri Lanka

Most of the world's forest has been cleared, cultivated, and then often abandoned. In many instances these areas have changed to successionally arrested grasslands, shrublands, or fernlands maintained by frequent fires and high herbivore populations. Many studies have shown that various herbaceous, nitrogen-fixing legumes can protect soil surfaces, retain soil moisture, improve soil fertility, and retard ground fires. Our objective was to ascertain if some of these species can potentially inhibit herbivory and satisfactorily establish in these arrested grassland areas to serve as sites for reforestation. We evaluated the potential for four species of nitrogen-fixing legumes (Calapogonium mucunoides, Centrosema pubescens, Desmodium ovalifolium, and Pueraria phaseoloides) to establish on exposed soil within successionally arrested grasslands of Panicum maximum and Cymbopogon nardus in the central hills of Sri Lanka. Four different sites within rectangular grassland areas were cleared of graminoids and sown with seed of each legume. Half of each clearing was protected from browsing rabbits and porcupines, and half was not protected. After 6 months, certain plots were destructively sampled to determine dry biomass gain for each species and treatment. Analyses of variance were performed to test for differences among sites, treatments, and species. All three factors revealed differences, indicating that species must be matched to site. On sites with high amounts of herbivory, D. ovalifolium had the greatest dry biomass gain after 6 months of growth, possibly because of its relatively low nitrogen and moisture content. Where herbivory was absent, P. phaseoloides and C. muconoides had the greatest dry biomass gain. Dry biomass gain of all four legume ground covers was low on sites with lowest pH and nutrient concentrations. Under conditions of low relative fertility and low pH, establishment of the tested legumes failed. Though soil moisture availability was not measured, we speculate that these low fertility sites were also prone to drought. Findings support the site-specific establishment of legume species for purposes of reforestation and watershed protection in central Sri Lanka. This work is applicable to other regions particularly dominated by successionally arrested grasslands with similar circumstances in other parts of south and southeast Asia.     

Germination and Emergence of Primed Grass Seeds Under Field and Simulated-field Temperature Regimes

Seed priming may enhance establishment success of cool-seasonrange grasses which must compete with annual weeds for earlyspring moisture. Previous priming studies have confirmed germinationrate enhancement for these species but relative treatment effectsunder field-temperature conditions have not been assessed. Weprimed seeds of thickspike wheatgrass [Elymus lanceolatus(Scribn.and J. G. Smith) Gould], bluebunch wheatgrass [Pseudoroegneriaspicata(Pursh) Löve], Sandberg bluegrass (Poa sandbergiiVasey.) and bottlebrush squirreltail [Elymus elymoides(Raf.)Swezey] and evaluated their relative emergence rate in threesoil types as a function of spring-planting date. Germinationresponse was simultaneously evaluated in laboratory germinatorsthat were programmed to simulate the field-temperature regimeat planting depth. Seed priming enhanced both germination andemergence rate with the greatest effect occurring during theearlier, cooler planting dates. Total emergence and emergencerate in the field were lower than for the equivalent germinationresponse in the laboratory. Thermal-germination response wasmodelled and predictions developed for evaluating potentialgermination under late winter/early spring soil-temperatureregimes. Modelling results predicted that greater germinationenhancement would have been possible at earlier planting datesthan were measured in the field experiment.Copyright 2000 Annalsof Botany Company Bunchgrass, germination, emergence, priming, rate, temperature     

Distribution and abundance of fungal sporocarps and diggings of the Tasmanian bettong,Bettongia gaimardi

Abstract The distribution and abundance of diggings of the Tasmanian bettong Bettongia gaimardi and sporocarps of hypogean fungi (the major dietary item of bettongs) were studied in an area of dry sclerophyll forest in northern Tasmania. Digging activity was greatest during August. Sporocarp production was expected to be greatest at this time due to high soil moisture levels. The distribution of both hypogean sporocarps and the diggings of bettongs was highly clumped. Degree of clumping of diggings varied seasonally being greatest in summer and lowest in winter. Digging activity was greatest in sandy soils and least in dolerite soils. This was thought to result from the lower fertility sandy soils having greater densities of sporocarps. Lateritic soils, although the most infertile, had fewer diggings than sandy soils. This is probably due to the difficulty of digging in these gravelly, often cemented soils. The depth of diggings was greatest in winter when soil moisture was high. Mesophellia was the most frequently occurring sporocarp and spores of this genus were the most abundant in the faecal pellets of bettongs.     

Effects of long-term experimental night-time warming and drought on photosynthesis, <Emphasis Type="Italic">F</Emphasis>v/<Emphasis Type="Italic">F</Emphasis>m and stomatal conductance in the dominant species of a Mediterranean shrubland

We conducted a night-time warming and drought field experiment for 7 years (1999–2005) in a Mediterranean shrubland. We focused on the two dominant shrub species, Erica multiflora L. and Globularia alypum L. and the tree Pinus halepensis L. and the final years to study the effects of the experimental night-time warming and drought on Fv/Fm, photosynthesis, and stomatal conductance. Warming treatment increased mean air temperature and mean soil temperature through the years by an average of 0.7 and 0.9°C respectively, and drought treatment reduced soil moisture through the years by an average of 19%. Warming tended to increase photosynthetic rates in E. multiflora, G. alypum and P. halepensis mostly in the cold seasons, when plants were more limited by temperature, as shown by the lowest values of Fv/Fm being detected in winter in the three studied species. A negative effect of warming was only detected for E. multiflora in summer 2003. Drought treatment generated different responses of net photosynthetic rates depending on the species, season and year. Stomatal conductance showed the same pattern as photosynthesis for the three studied species, displaying seasonal and inter-annual variability, although with an overall negative effect of drought for P. halepensis. Photosynthetic rates decreased significantly in the dry winter 2005 and spring 2005 in comparison to the same seasons of 2003 and 2004. There were positive correlations between the photosynthetic rates in different seasons for E. multiflora, G. alypum and P. halepensis and the soil moisture of the week prior to measurements. The great variation in the photosynthetic rates was thus explained in a significant part by soil moisture levels. The lowest Fv/Fm values usually corresponded with lowest stomatal conductances suggesting that drought stress could be associated to stress by low temperatures in winter.     

The Function of the Hilum in Some Papilionaceae in Relation to the Ripening of the Seed and the Permeability of the Testa

In seeds of Trifolium repens, T. pratense, and Lupinus arboreus,the hilum is a hygroscopically activated valve in the impermeableepidermis of the testa. When relative humidity was low the fissurein the hilum opened permitting the seed to dry out; when therelative humidity was high the fissure closed obstructing theabsorption of moisture. During seed-ripening the moisture contentfell readily to approximately 25 per cent., and thereafter moreslowly until the epidermis became impermeable at approximately14 per cent, moisture content. Further drying of the seed tookplace only by diffusion of water vapour through the hilum. ‘Hard’seeds tended to have a moisture content in equilibrium withthe lowest relative humidity to which they had been exposed.They absorbed moisture under conditions of gradually increasingrelative humidity such that the hilar fissure remained open.The duration of the impermeable condition increased with thedegree of desiccation brought about by loss of water throughthe hilum.     

Effects of soil moisture deficits on the water relations of bambara groundnut (Vigna subterranea L. Verdc.)

The components of leaf water potential (_l) and relative watercontent (RWC) were measured for stands of bambara groundnut(Vigna subterranea) exposed to three soil moisture regimes incontrolled-environment glasshouses at the Tropical Crops ResearchUnit, Sutton Bonington Campus. Treatments ranged from fullyirrigated (wet) to no irrigation from 35 days after sowing (DAS)(dry). RWC values varied between 92–96% for the wet treatment,but declined from 93% to 83% in the dry treatment as the seasonprogressed. _l at midday decreased in both the wet and dry treatments,but the seasonal decline was more pronounced in the latter:seasonal minimum values were –1.19 and –2.08 MPa,respectively. Plants in the wet treatment maintained turgor(_p) at about 0.5 MPa throughout the season, whereas values inthe dry treatment approached zero towards the end of the season.There was a linear relationship between _p and _l9 with _p approachingzero at a _l of –2.0 MPa. Mean daily leaf conductance wasconsistently higher in the wet treatment (0.46–0.79 cm^-1)than in the intermediate and dry treatments (0.13–0.48cm s^-1 Conductances in the intermediate and dry treatments weresimilar, and the lower evapotranspirational water losses inthe latter were attributable to its consistently lower leafarea indices (L): L at final harvest was 3.3, 3.3 and 1.9 forthe wet, intermediate and dry treatments. Bambara groundnutwas apparently able to maintain turgor through a combinationof osmotic adjustment, reductions in leaf area index and effectivestomatal regulation of water loss. Key words: Vigna subterranea, water relations, soil moisture