Arbuscular mycorrhizae and soil/plant water relations. Robert M. Augé. Department of Plant Sciences, Joe Johnson Drive, University of Tennessee, . Arbuscular mycorrhizae and soil/plant water relations . Auge, R.M.. Access the full text: NOT AVAILABLE. Lookup the document at: google-logo. Augé, R. M. Arbuscular mycorrhizae and soil/plant water relations. Can. J. Soil Sci. – The water relations of arbuscular mycorrhizal (AM) plants.
The greatest arbuscular colonization was associated with the highest N and P concentrations in plant tissue, suggesting a correspondence with increases in the rate of nutrient transfer between the symbiotic partners. Water content, salinity and sodicity in soil were positively associated with AM root colonization and arbuscule colonization in L.
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There were distinct seasonally related effects with respect to both spore density and AM colonization, which were independent of particular combinations of plant species and soil sites. Other benefits of the mycorrhizal symbioses are to reduce the detrimental effect of soil salinity Jindal et al. Natural grassland soils are commonly deficient in essential nutrients N and P to sustain maximum plant growth Ginzo et al. Field studies showed that grassland plants can be colonized by AM fungi under a wide range of soil conditions Stutz et al.
AM fungi are believed to require well-aerated soils and are considered to be poorly adapted to conditions in flooded environments Mosse et al. Furthermore, Mendoza et al. Despite the importance of AM fungi in the physiology and nutrition of plants, little is known about the factors likely to influence the seasonal dynamics of AM fungi along a saline-sodic gradient.
Arbuscular mycorrhizae and soil / plant water relations - Semantic Scholar
To better understand how soil properties and plant nutrient status especially N and P influence AM—plant symbioses requires the investigation of the association between soil properties and the temporal variations in AM colonization morphology under field conditions. Although relationships between P uptake and root colonization by AM fungi have been investigated under controlled conditions, several differences could be found in grassland plants under field conditions.
Plant nutrient uptake mediated by AM fungi depends on how much of the soil can be exploited by the external hyphae, the rate at which hyphae take up available nutrients and how much of the internal fungus is active in transferring nutrients to the plant. Greenhouse experiments showed that an increase of P concentration in soil or plant tissue was related to a decrease in the total length of colonized root and the proportion of root length colonized by arbuscules Braunberger et al.
However, high levels of P inflow do occur at certain periods during the growing season, suggesting that AM fungi may promote plant nutrient uptake during these periods. There is little published literature relating to the temporal dynamics of AM root colonization morphology in grassland plants associated with changes in N and P plant status and soil properties in stressful environments.
Even when it is accepted that grassland plants can be colonized by AM fungi along a wide range of soil conditions, associating changes in nutrient uptake with changes in AM root colonization are difficult to investigate.
When soil conditions change, plant community structures also change, and hence cause—effect relationships are difficult to establish.
An approach could be to study grassland plants with the ability to grow across a wide range of soil properties in the same location under the same climate conditions. These plants that occur across a wide soil gradient, as opposed to plants with a more narrow ecological distribution, may have a different response to mycorrhizas, as part of an overall more plastic strategy.
This was done in an attempt to explain whether seasonal variations in plant nutrient demands result in changes in AM root colonization morphology and to know whether these changes are associated with soil characteristics. The authors specifically aim to test the following hypotheses: The seasonal mean temperature and accumulated rainfall values at the site were, respectively: The experimental grassland extends over a topographic gradient that determines different soil characteristics and dynamic hydrologic and saline gradients.
A transect m long was laid across it, with the lowest end prescribed as a reference point for both distance and relative height for another three sampling sites; this was denoted Site 1, and distance and height co-ordinates set to 0, 0 m.
Subsequent sites were set as follows: Site 2 at0. Three forage species commonly present in the grassland were selected as test plants: The precipitation regime thus involves both a long dry period and short term periods of water stress, and may select for specific plant morphological and physiological adaptations Schwinning and Ehleringer ; Schwinning and Sala Boswellia is ecologically adapted to such pulsed growth conditions Gebrehiwot et al.
In an earlier study, we concluded that the AM symbiosis contributes to this adaptation and hence makes a major contribution to establishment, growth, and survival of this woodland species under the prevailing harsh climate Birhane et al.
Root colonization levels were higher during the dry than during the wet season. As the plants were leafless during the dry period although Boswellia possesses photosynthetic stemsit seems plausible that carbon gain by the plant and carbon expenditure by the fungus are temporally disconnected. This temporal disconnect could be a specific adaptation to pulsed resource availability Birhane et al.
A temporal disconnect as a strategy of drought tolerance has been described before in the vernal herb Erythronium americanum Lapointe and Molard ; Lapointe In this study, we tested the effect of the AM symbiosis in combination with water availability pulsed or not for three Boswellia seedling age groups to determine seedling performance carbon and nutrient acquisition, and water use.
Mycorrhizal plants are larger than non-mycorrhizal plants; Mycorrhizal Boswellia seedlings have higher gas exchange, leaf water potential, and relative water content than seedlings without AM; Mycorrhizal benefit is larger under water-pulsed conditions irregular water supply than under conditions of regular watering; Higher biomass in mycorrhizal seedlings under water-pulsed conditions is a result of higher assimilation rate and water use efficiency.
Seedling preparation and selection Seeds from adult Boswellia trees from the dry deciduous woodlands in Abergelle, northern Ethiopia, were collected in March Healthy trees with a single stem and with uniform seed setting were selected for seed collection. Seeds were directly picked by hand from tree branches either by climbing or standing on the ground depending on tree height. Germination took place in plastic trays filled with autoclaved pure river sand under greenhouse conditions.
Potted seedlings were placed on metal mesh benches and were watered regularly using micro-sprinkler irrigation every other day to field capacity until the plants were ready for the experiment.
Arbuscular mycorrhizae and soil/plant water relations - Canadian Journal of Soil Science
Dimethoate was sprayed to ward off ants and aphids which were observed on leaves. At the same time, half of the remaining seedlings were inoculated and all were transplanted to larger perforated l plastic containers. Preparation of inoculum of AM fungi Spores of AM fungi were collected during the dry season from the rhizosphere of the same Boswellia trees by the wet sieving and decanting method Brundrett et al.
Most spores belonged to the genus Glomus Birhane et al. Spore cultures were maintained on plants of Sorghum bicolor. The fungal inoculum added to the seedlings consisted of a mixture of soil, spores, and root fragments, produced from the rhizosphere of pre-colonized Sorghum bicolor plants. In order to mimic the natural growth conditions for the seedlings, the potting soil was also excavated from Abergelle, in a similar habitat where Boswellia trees naturally grow.
Control seedlings were planted in sterilized soils. Experimental design and treatments The experiment consisted of a three-factorial design: AM fungi present or absentwater supply continuous watering vs.
During that period, seedlings died back above-ground. When watered, pots were filled to field capacity, based on their mass. The treatment units were arranged on greenhouse benches in a completely randomized design. There were 11 replications which gave a total of seedlings since 12 seedlings were initially harvested, seedlings were actually planted and exposed to the actual treatments. We determined plant size, biomass, and growth rate. Total shoot length plant height was measured using a graduated meter, and root collar diameter was measured using a digital caliper.
The number of fully developed leaves was assessed for each seedling. Total root length was estimated using the grid line intersect method Tennant The number and length of primary roots per plant were assessed and determined. Relative growth rate was calculated according to Hunt and Chiariello et al.
Plant nutrient analysis Mineral status of the plants was determined by conducting shoot and root tissue elemental analysis. Samples were then wet-digested and analyzed for N, P, and K.
- Arbuscular mycorrhizae and soil / plant water relations
- Arbuscular mycorrhizae and soil/plant water relations 
- Canadian Journal of Soil Science
Total N was determined using the standard Kjeldahl method, P colorimetrically by spectrophotometer, and K by flame photometry Anderson and Ingram Mycorrhizal colonization Mycorrhizal colonization was assessed using the grid line intersection method Giovannetti and Mosse