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Turgor Maintenance in Rosa rugosa Grown at Three Levels of Nitrogen and SUbjected to Drouqht'
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The influence of N fertilization on turgor maintenance was determined in leaves from well-watered and droughted Rosa rugosa L. Plants were fertilized for 60 days with a complete fertilizer with N at levels of 0, 200 or 500 ppm and then subjected to several drought cycles for 22 days. Plants receivmg no N were stunted and chlorotic, but had the greatest full saturation turgor pressure and symplastic osmolality, and the lowest full saturation osmotic potential, after drought. These plants also maintained higher turgor across a range of leaf water potentials and relative water contents. Leaf water content at full turgor and relative water content at the turgor loss point were also lower in plants without N. N treatments of 200 and 500 ppm had similar water relations under both well-watered and drought conditions.
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... According to earlier studies (Kärkkäinen, 2003, pp. 164;Augé et al., 1990) the relative water content may vary within samples of same species depending on growth conditions, precipitation, stress levels and the genetics of the plants. No datasets for the average moisture percentages of the assessed plants were found. ...
Plants and soil are natural regulators of atmospheric CO2. Whereas plants sequester atmospheric carbon, soils deposit it for decades. As cities become increasingly more densely built, the available land area for such ecosystem services may decrease. We studied seven different housing areas in the Finnish city of Espoo to ascertain the extent to which site efficiency affects to the ecosystem services if the full life-cycle GHG emissions of these areas are taken into account. The results show that the impact of CO2 uptake through carbon sinks in growing plants and the uptake of soil organic carbon vary greatly. Its share of all emissions varied from a marginal value of 1.2% to a more considerable value of 11.9%. The highest potential was calculated for a detached house located on a large site, while the weakest was calculated for compact apartment blocks. The study revealed that in order to quantify this potential more accurately, several knowledge gaps must first be addressed. These include impartial growth algorithms for Nordic wood species, missing accumulation factors for soil organic carbon in cold climates and statistical maintenance scenarios for gardens.
... Instead, the root water content increased in seedlings at high nutrients and CO 2 . Typically, nutrient status of plants affects cell water relations by changing stomatal sensitivity, increasing water use efficiency, and altering turgor and osmotic adjustments (Aug e et al. 1990). Moreover, if the seedlings were defoliated and grown at low nutrients, the root water content decreased under both ambient and elevated CO 2 (Fig. 2). ...
Climate warming increases the risk of insect defoliation in boreal forests. Losses in photosynthetically active surfaces cause reduction in net primary productivity and often compromise carbon reserves of trees. The concurrent effects of climate change and removal of foliage on root growth responses and carbohydrate dynamics are poorly understood, especially in tree seedlings. We investigated if exposures to different combinations of elevated temperature, CO2, and nutrient availability modify belowground carbon gain and root morphology in artificially defoliated 1-year-old silver birches (Betula pendula). We quantified nonstructural carbohydrates (insoluble starch as a storage compound; soluble sucrose, fructose, and glucose) singly and in combination in fine roots of plants under winter dormancy. Also the total mass, fine root proportion, water content, and length of roots were defined. We hypothesized that the measured properties are lower in defoliated birch seedlings that grow with ample resources than with scarce resources. On average, fertilization markedly decreased both the proportion and the carbohydrate concentrations of fine roots in all seedlings, whereas the effect of fertilization on root water content and dry mass was the opposite. However, defoliation mitigated the effect of fertilization on the root water content, as well as on the proportion of fine roots and their carbohydrate concentrations by reversing the outcomes. Elevation in temperature decreased and elevation in CO2 increased the absolute contents of total nonstructural carbohydrates, whereas fertilization alleviated both these effects. Also the root length and mass increased by CO2 elevation. This confirms that surplus carbon in birch tissues is used as a substrate for storage compounds and for cell wall synthesis. To conclude, our results indicate that some, but not all elements of climate change alter belowground carbon gain and root morphology in defoliated silver birch seedlings.
... Instead, the root water content increased in seedlings at high nutrients and CO 2 . Typically, nutrient status of plants affects cell water relations by changing stomatal sensitivity, increasing water use efficiency, and altering turgor and osmotic adjustments (Aug e et al. 1990). Moreover, if the seedlings were defoliated and grown at low nutrients, the root water content decreased under both ambient and elevated CO 2 (Fig. 2). ...
Climate warming increases the risk of insect defoliation in boreal forests. Losses in photosynthetically active surfaces cause reduction in net primary productivity and often compromise carbon reserves of trees. The concurrent effects of cli-mate change and removal of foliage on root growth responses and carbohydrate dynamics are poorly understood, especially in tree seedlings. We investigated if exposures to different combinations of elevated temperature, CO 2 , and nutrient availability modify belowground carbon gain and root morphology in artificially defoliated 1-year-old silver birches (Betula pendula). We quantified nonstructur-al carbohydrates (insoluble starch as a storage compound; soluble sucrose, fruc-tose, and glucose) singly and in combination in fine roots of plants under winter dormancy. Also the total mass, fine root proportion, water content, and length of roots were defined. We hypothesized that the measured properties are lower in defoliated birch seedlings that grow with ample resources than with scarce resources. On average, fertilization markedly decreased both the propor-tion and the carbohydrate concentrations of fine roots in all seedlings, whereas the effect of fertilization on root water content and dry mass was the opposite. However, defoliation mitigated the effect of fertilization on the root water con-tent, as well as on the proportion of fine roots and their carbohydrate concen-trations by reversing the outcomes. Elevation in temperature decreased and elevation in CO 2 increased the absolute contents of total nonstructural carbohy-drates, whereas fertilization alleviated both these effects. Also the root length and mass increased by CO 2 elevation. This confirms that surplus carbon in birch tissues is used as a substrate for storage compounds and for cell wall synthesis. To conclude, our results indicate that some, but not all elements of climate change alter belowground carbon gain and root morphology in defoliated silver birch seedlings.
... Rosa rugosa is extremely tolerant of seemingly adverse environmental conditions. In its native and artificial habitats, R. rugosa is extremely drought tolerant, salt tolerant, fire tolerant, and tolerant to destruction of above ground tissue, and sand covering (Belcher 1977;Dirr 1978;Augé et al. 1990;Didriksen 1999;Tsuda et al. 1999;Bruun 2005). Symptomatic of this tolerance was the occurrence of colonies in Cheticamp just above the high tide mark and along roadsides to the plow line. ...
Rosa rugosa is described for the first time as an invasive species associated with coastal sand dunes in Atlantic Canada. Our surveys of 24 beaches on western Cape Breton Island and the mainland of northern Nova Scotia from Cheticamp to Fox Harbour showed that 11 of the dune systems (ca. 45%) were colonized. This was more prevalent in Cape Breton where R. rugosa occurred on 9 of 13 systems, whereas only 2 of 9 mainland systems were colonized. Four dunes (three in Cape Breton) were considered heavily colonized with 0.4 - 8.8% of the dune area with cover of R. rugosa. These beaches had 12 42 independent clumps with almost monospecific stands over 90 % cover. In general, heavily colonized beaches were found adjacent to communities where extensive domestic planting and hedges of R. rugosa occurred and where escapes onto road-sides had occurred. In most colonized beach systems, rhizomes from clones extended 1 5 m to produce younger shoots. The absence of Ammophila Lathyrus maritimus and Myrica pensylvanica, from the interior of many clumps of R. rugosa suggests that native dune communities are being negatively impacted. This exacerbates dune integrity already compromised by impacts of sea level rise.
... ( ) , , , , Rosa rugosa is renowned among horticulturalists for its hardiness and its great tolerance of frost, heat, drought ( Türk 1995); (B) dune scrub (Salicion arenariae) from the west coast of Jutland (Isermann 1999); and (C-D) speciesrich sand grassland communities (class Armerion elongatae) from the North Frisian island of Amrum (Türk 1995 Rosa rugosa can maintain turgor under severe drought. In a garden experiment, Augé et al. (1990) showed that plantlets subjected to several drought cycles had a higher leaf water potential and symplastic osmolality than had well-watered plantlets. Despite being stunted and chlorotic, drought-stressed plantlets receiving no additional nitrogen had the highest full saturation turgor pressure and symplastic osmolality of all treatments. ...
... This might explain the higher leaf water potentials of seedlings growing in burned versus unburned areas (Wellington 1984). Plants growing under conditions of higher nutrient availability can exhibit a greater availability to maintain stomatal conductance, photosynthesis, and growth under dry conditions (Radin & Parker 1979;Lahiri 1980;Radin & Ackerson 1981;Abrams 1988, but see Augé et al. 1990 andKleiner et al. 1992). Because the protection against herbivores was vandalized in 1991, differential herbivory between sites cannot be excluded as a factor in later years. ...
The Chilean matorral is characterized by multispecific shrub clumps in dry areas but has a continuous canopy in wetter sites. It has been hypothesized that this difference is due to easier recolonization of open patches by shrub seedlings under more mesic conditions. Within the mesic range of the matorral we designed a field experiment to compare shrub seedling emergence, growth, and survival under the closed canopy of a secondary forest versus three types of open patches: burned, cleared of shrubs but with a herbaceous layer present, and clear without a herbaceous layer. After the first summer, survival of Quillaja saponaria seedlings was 75% in the burned site, 30% in the cleared patch without herbaceous vegetation, and 15% with herbaceous vegetation present, whereas there was 0% survival under the secondary forest canopy. After eight years, the percentages had dropped to: 22%, 12% and 3%, respectively. These results contrast strongly with the seedling establishment patterns in drier areas of the matorral where early seedling survival is higher under the shade of large shrubs. In the experimental mesic sites, seedlings did best on the burned site, not only in terms of survival, but also in terms of growth. After one year, seedling mean height was 10.2cm in the burned site, whereas 3.8cm and 5.3cm in the cleared patches without and with herbaceous respectively. After eight years, mean height differences between treatments had increased further: 147.7cm in the burned site, 40.3cm in the cleared patch without herbaceous cover and 13cm in the cleared patch with herbs. Our results indicate that the facilitative effect of nurse shrubs on seedling establishment found in dry ranges of the matorral is less important in more mesic sites. This difference may explain the continuous shrub cover in relatively mesic areas as opposed to the characteristic patchy structure of the matorral in its drier range.
During August and September 2010, we surveyed the entire 20.4 km perimeter of Brier Island, Nova Scotia, for the invasive shrub Rosa rugosa (Rugosa Rose). This island in the outer reaches of the Bay of Fundy of Nova Scotia is geographically isolated and relatively undeveloped. Our objective was to determine the extent and mechanism of the invasion of R. rugosa into different coastal habitats to gain insight into the potential threat to native biodiversity from the unchecked population growth of this monopolizing, rank shrub. Over 300 colonies of R. rugosa with mean height over 1 m occupied 2089 m of the island perimeter within 10 m of the top of the beach. The mean distance between colonies was about 61 m and the maximum distance was 1927 m. At least 33 colonies formed almost impenetrable walls, each over 10 m in length, and 2 colonies occupied about 500 m2 each. Rosa rugosa had greatest density on a sand-gravel beach on which 88 colonies occupied 22% of the area and 33% of the beach margin. Exponential growth of the population (inferred from aerial photographs from 1970, 1988, and 2000) may be due to the various systems of seed dispersal. Agents include primary (American Mink, Neovison vison, and Red Squirrel, Tamiascurius hudsonicus) and secondary (an unidentified rodent) biotic dispersers. Longer distance dispersal may include Coyotes (Canis latrans), off-road vehicles and deposition of fruits by currents and waves. The main sites of seedling establishment are native habitats, such as dune grass and seashore Seaside Plantain (Plantago maritima) zones, albeit modified by this exotic rose. Dispersal of colonies contradicts a hypothesis of dispersal from human habitation along roads and tracks to the coastal habitats. We conclude that R. rugosa is having a significant impact on marine coastal plant communities and has the potential to dominate windswept shrub habitats on coastlines of much of Nova Scotia.
Our aim in this study was to determine how well phenotypic variation iri foliar concentrations of carbon-based secondary compounds (CBSCs) in woody plants can be predicted on the basis of two resource-based hypotheses, i.e. the carbon-nutrient balance (CNB) and growth-differentiation balance (GDB) hypotheses. We conducted a meta-analysis of literature data with respect to responses of CBSCs, carbohydrates and nitrogen to six types of environmental manipulations (fertilization with nitrogen or phosphorus, shading, CO2 enrichment, drought stress, ozone exposure): Plant responses to nitrogen fertilization, shading and CO2 enrichment in terms of pooled CBSCs and carbohydrates were consistent with predictions made with the two hypotheses. However, among biosynthetically distinct groups of CBSCs only concentrations of phenylpropanoid-derived compounds changed as predicted; hydrolyzable tannins and terpenoids, in particular, were less responsive. Phosphorus fertilization did not affect concentrations of CBSC or primary metabolites. Plant responses to drought and ozone exposure presumably were driven by plant demands for particular types of compounds (osmolites in the case of drought and antioxidants in the case of ozone exposure) rather than by changes in resource availability. Based on the relative importance of the treatment effects, we propose a hierarchical model of carbon allocation to CBSCs. The model implies that CBSC production is determined by both resource availability and specific demand-side responses. However, these two mechanisms work at different hierarchical levels. The domain of the CNB and GDB hypotheses is at the high hierarchical levels, predicting the total amount of carbon that can be allocated to CBSCs. Predicting altered concentrations of individual CBSCs, i.e. low hierarchy levels, probably demands biosynthetically detailed models which also take into account the history of plant interactions with biotic and abiotic factors.
The water relations of shoots of young jack pine (Pinus banksiana Lamb.) seedlings were examined 6 and 15 weeks after the initiation of four different dynamic nitrogen (N) treatments using a pressure-volume analysis. The N treatments produced a wide range of needle N concentrations from 12 to 32 mg g−1 dry mass and a 10-fold difference in total dry mass at 15 weeks. Osmotic potential at full turgor did not change over the range of needle N concentrations observed. Osmotic potential at turgor-loss point, however, declined as N concentrations decreased, indicating an increased ability of N-deficient jack pine plants to maintain turgor. The increase could be attributed largely to an increase in cell wall elasticity, suggesting that elasticity changes may be a common, significant adaptation of plants to environmental stresses. Dry mass per unit saturated water almost doubled as needle N level dropped from 32 to 12 mg g−1 and was inversely correlated to the bulk modulus of elasticity. This suggests that cell wall elasticity is determined more by the nature of its cross-linking matrix than by the total amount of cell wall material present. Developmental change was evident in the response of some water relation variables to N limitation.
The morphological and physiological responses to nitrogen (N) limitation in jack pine (Pinus banksiana Lamb.) seedlings were studied following the initiation of four different dynamic N treatments for six and 15 weeks. The N treatments produced needle N concentrations from 11 to 31 mg g-1dry weight, and seven-fold difference in dry weight at 15 weeks. Low-N jack pine seedlings: 1) had an higher root/shoot ratio; 2) extended their tap root more rapidly; 3) were better able to maintain turgor when shoot water potential declined; and 4) had a larger dry weight fraction and apoplasmic fraction than seedlings with higher foliar N concentrations. These responses may contribute collectively to enhance drought tolerance in N-limited plants, thereby affecting seedling quality. Modifying nursery fertilization regimes, other than optimal as usually applied, may thus be needed to produce stock for use on particularly droughty sites. Knowledge of the nature of drought at a particular site could be an important consideration when making decisions related to fertilization.
Osmotic adjustment in response to onset of winter dormancy was characterized in well-watered, potted sweetgum ( Liquidambar styraciflua L.) and southern magnolia ( Magnolia grandiflora L.) growing outdoors in Knoxville, Tenn. Analyses of water potential isotherms indicated that adjustment occurred in both species, with osmotic potential (ψ π ) at full turgor decreasing 0.8 MPa in sweetgum (by the time of first color, 27 Oct.) and 1.0 MPa in magnolia (by 1 Dec.). Osmotic adjustment occurred despite the fact that plants did not suffer osmotic stress; morning and afternoon leaf relative water content (RWC) and leaf water potential (ψ) remained high throughout the fall. Leaf conductance was halved in sweetgum and doubled in magnolia as the autumn progressed. A correlation was found in magnolia between turgid : dry weight ratio and ψ π at full turgor. Tissue elasticity decreased somewhat, as the elastic modulus increased ≈2 to 3 MPa in each species through the autumn. Water potential isotherms changed most dramatically through the autumn in magnolia. Initially, ψ was −1 MPa at 82% RWC and, by December, leaves were able to withstand ψs of −3 MPa before RWC dropped to 82%. These changes are similar to those commonly reported as responses to drought or salinity.
This review examines the impact of drought and salinity on agricultural production in both the semi- arid and humid regions of the world. The frequency and nature of drought events and some recent approaches to drought prediction are discussed along with the distribution of salinity and the various factors leading to its occurrence under both irrigated and dryland conditions. Strategies to minimize the impact of drought and salinity on the rural community and on the stability of land resources have been developed largely in high-income countries. However, because of the high cost, little has been done in the developing world where extensive areas of valuable land are deteriorating, representing a serious threat to food security.
Nitrogen content in 10 plant samples of widely varying concentrations of N, P, and K was measured by a H2SO4—H2O2 ashing procedure and the AutoAnalyzer system and found comparable to nitrogen content obtained by conventional Kjeldahl analysis. Phosphorus content measured by the AutoAnalyzer system on the same H2SO4-H2O2 ashing was similar to that obtained by dry-ashing combined with the molybdo-vanadate procedure. Potassium analyses on the solutions from the two ashing procedures by atomic absorption spectroscopy were comparable. Details are presented for simultaneous N and P analysis by the AutoAnalyzer and for K analysis by atomic absorption on plant material performed on a single H2SO4-H2O2 digest at a rate of 160 samples per week by one technician.
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Experiments with simulated swards of perennial ryegrass (Lolium perenne L.) grown in flowing nutrient solution with NO3- held at 0.1 mg N I−1 show that the rate of NO3- uptake was related to diurnal, day-to-day, and seasonal changes in radiation. In summer the diurnal variation in NO3-uptake ranged from 25 to 50 mg N m−2 h−1 and the day-to-day variation ranged from 500 to 1500 mg N m−2 d−1. Mean daily rates of uptake over 12 d periods in summer and in winter averaged 908 and 44 mg N m−2, respectively. The pattern of NO3- uptake followed that of CO2 flux with the maximum rate of the former occurring 5 or 6 h after the maximum CO2 influx. After defoliation, NO3- uptake was severely curtailed for 2 d concomitant with a very small influx of CO2. Analysis of the changes that occurred in the rate of NO3- uptake immediately after the switching on or off of artificial light suggests that two reversible processes may be involved
in the relation between NO3-uptake and radiation, one with a longer and the other with a shorter time constant.
. The objective of the present work was to study the effect of nitrogen deficiency on drought sensitivity of tall fescue plants. The authors compared photosynthetic and stomatal behaviour of plants grown at either high (8 mol m−3) or low (0.5 mol m−3) nitrogen levels during a drought cycle followed by rehydration. Other processes investigated were stomatal and non-stomatal inhibition of leaf photosynthesis, water use efficiency and leaf rolling. Plants were grown in pots in controlled conditions on expanded clay. A Wescor in situ hygrometer placed on the leaf base outside the assimilation chamber permitted, simultaneously to leaf gas exchange measurements, monitoring of leaf water potential. Drought was imposed by withholding water from the pot. CO2 uptake and stomatal conductance decreased and leaves started to roll at a lower leaf water potential in the high-N than in the low-N grown plants. Stomatal inhibition of leaf photosynthesis seemed larger in the low-N than in the high-N plants. Water-use efficiency increased more in the high-N than in the low-N grown plants during the drought. The decrease of photosynthesis was largely reversible after rehydration in low-N but not in high-N leaves. The authors suggest that low-N plants avoid water deficit rather than tolerate it.
The role of nitrate in osmotic control was studied with Italian ryegrass grown in a nutrient solution in a climate room. Quantum-flux density, osmotic potential of the nutrient solution and availability of nitrate and chloride were varied independently. Plants at high quantum flux density (650 mol m–2 s–1) had a lower osmotic potential, a higher carbohydrate concentration and a lower nitrate concentration than plants at low quantum flux density (310 mol m–2 s–1), the decrease in nitrate concentration was osmotically equivalent to the increase in carbohydrate concentration. When nitrate in the nutrient solution was partly replaced by chloride, the chloride taken up substituted an equivalent part of the nitrate in the plant. It is concluded that nitrate plays a role in osmoregulation of the plant and compensates for a shortage of other solutes.
Nitrogen deficiency in cotton plants (Gossypium hirsutum L.) considerably increased the sensitivity of stomata to water stress. At air temperatures of 27, 35, and >/=40 C, threshold potentials for complete stomatal closure were -10, -15, and -26 bars in N-deficient plants and -20, -20, and -30 bars in high-N plants, respectively. This three-way interaction among N supply, water potential, and air temperature was similar to that exerted on leaf expansion. The effects of N supply on stomatal behavior could not be explained on the basis of either osmotic or structural considerations. Rather, effects of N deficiency on mesophyll and stomata were independent and divergent. Stomatal behavior may impart a stress avoidance type of drought resistance to N-deficient plants.