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Mn uptake from MnCl2 solution and chlorophyll fluorescence (as a selected vitality parameter) were studied in the epiphytic lichens Lobaria pulmonaria (tripartite, heteromerous lichen with the green alga Dictyochloropsis as primary photobiont and Nostoc in cephalodia), Nephroma helveticum (bipartite, heteromerous lichen with Nostoc photobiont) and Leptogium saturninum (bipartite, homoiomerous lichen with Nostoc photobiont). Extracellular adsorption and intracellular uptake of Mn increased in the order L. pulmonaria < N. helveticum < L. saturninum. Mn increasingly reduced the effective quantum yield of photosystem 2 (?2) in the same order. CaCl2 and MgCl2 alleviated the Mn-induced reduction of ?2. Moist thalli of...
Cheatgrass (Bromus tectorum L.) has come to dominate millions of hectares of rangeland in the Intermountain western United States. Previous studies have hypothesized that one mechanism conferring a competitive advantage to this species is the ability to germinate rapidly at low temperatures in the fall, winter and spring and, therefore, initiate growth and establishment more rapidly than more desirable perennial bunchgrass species. In this experiment, we developed thermal-germination-response models for multiple seedlots of cheatgrass and five perennial grass species. We conducted sensitivity analysis on potential-cumulative-germination response to a 38-year simulation of field-variable conditions of seedbed temperature...
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The frequency of extreme drought events is projected to increase under global climate change, causing damage to plants and crop yield despite potential acclimation. We investigated whether grasses remain acclimated to drought even after a harvest and remember early summer drought exposure over a whole vegetation period. For this, we compared the response of Arrhenatherum elatius plants under a second, late, drought (they were pre-exposed to an early drought before), to plants exposed to a single, only late, extreme drought. Surprisingly, the percentage of living biomass after a late drought increased for plants that were exposed to drought earlier in the growing season compared to single-stressed plants, even after...
We hypothesize that drought-avoidance in Gutierrezia sarothrae populations is characterized by well-developed lateral roots. Root growth and hydraulic conductance were studied in four populations of Gutierrezia sarothrae. Seedlings from a Malta, Idaho (ID) seed source had four times higher root/shoot ratio (P<0.05), but only 17% hydraulic conductance of those from Tahoka, Texas (TA) seed source. Consequently, transpiration surface area of the ID seedlings was 17% that of the TA seedlings. There was no difference in total root length between the seedlings, but hydraulic conductance per unit root length was 3.8 fold greater (P<0.05) in the TA seedlings, which was accompanied by a lower specific lateral root length...
The aridland shrub species, Artemisia tridentata (big sagebrush) and Chrysothamnus nauseosus (rubber rabbitbrush), are distributed widely in the Intermountain region of western North America. Earlier research indicated that A. tridentata can utilize upper soil water from transient summer rain events while C. nauseosus apparently cannot, although both species have similar rooting depths. Thus, we hypothesized that C. nauseosus relies more on deep water than A. tridentata, while A. tridentata can take advantage of soil moisture in upper soil layers. We examined this hypothesis by growing A. tridentata and C. nauseosus in two-layer pots in which soil water content in the upper and lower layers was controlled independently....
The root depths and maximum lateral spreads of two shrubs and four perennial grass species were examined in disturbed (backfilled) and undisturbed soil using 131I as a soil injected radiotracer. Although individual species differences were found, root distributions were not universally larger in one soil type or another. Big sagebrush (Artemisia tridentata ssp. wyomingensis) roots were detected deeper in the undisturbed soil (1.00 vs 0.75 m), while green rabbitbrush (Chrysothamnus viscidiflorus) roots were detected deeper in undisturbed soil (1.00 vs 0.50 m). Streambank wheatgrass (Elymus lanceolatus) and crested wheatgrass (Agropyron cristatum) roots were detected deeper in disturbed soil (1.00 m vs 0.75 m). Basin...
We hypothesise that genotypic differences in transpiration and root growth in the southern and northern populations of Gutierrezia sarothrae are driven by growing season vapour pressure deficit (VPD) and that ecotypic differentiations are linked to corresponding variations in tissue and leaf water relations. Seedlings from an Idaho (ID) and a Texas (TX) seed source were grown either in an open nursery (full sunlight) or under shade. There were no population differences in transpiration, root growth and tissue water relation parameters when the plants were grown under the shade. However, significant population differences were observed in the plants grown in the open where VPD was substantially higher. Transpiration...
Pressure-volume analyses were done on a half-shrub broom snakeweed (Gutierrezia sarothrae) subjected to different soil water regimes under pot- and field-grown conditions. Under pot and field conditions, water deficit decreased water and osmotic potentials. In the severely droughted pot-grown, osmotic potential at full turgor (?100) decreased by 0.44 MPa due to reduced symplastic volume, the result of a decreased leaf turgid to dry weight (TW/DW) ratio. A reduction of 0.86 MPa in ?100 was observed in the field-grown plants subjected to the first drought cycle, but increased cell wall elasticity occurred in the second drought cycle. The lowered ?100 was attributed to osmotic adjustment and reduced symplastic volume....
Relative water content (RWC) and water potential were compared for leaves of several plant species exposed to a warming manipulation at the Rocky Mountain Biological Laboratory, near Crested Butte, Colorado, USA, to test the hypothesis that species-specific changes in water relations parameters will occur in response to future increases in planetary air temperatures. Leaves of Artemisia tridentata, Erigeron speciosus, Festuca thurberi, Helianthella quinquinervis, Potentilla fruticosa, Potentilla gracilis and Rhodiola integrifolia were collected from plants growing in situ in control and infrared (IR)-heated (22 W m−2) plots in a meadow near the upper elevational distribution limit for A. tridentata. For six of...
Seeds from northern (Idaho) and southern (New Mexico and Texas) populations of broom snakeweed (Gutierrezia sarothrae) were germinated in a greenhouse and the seedlings grown in a soil mixture in 30-cm deep (19-1) plastic pots for 50 days. The pots were then fastened onto the top of similar pots and the seedling root systems were allowed to grow into the lower pots for 4 weeks through punctures in the bottoms of the upper pots. Soil water extraction from four different depths was measured using time domain reflectometry (TDR) 2 weeks after roots had begun to grow into the lower pots. The two New Mexico populations (Jornada and Mountainair) and a population from Plains, Texas extracted more water from deeper (greater-or-equal,...
    map background search result map search result map Do plants remember drought? Hints towards a drought-memory in grasses Gas exchange and growth responses of the desert shrubs Artemisia tridentata and Chrysothamnus nauseosus to shallow- vs. deep-soil water in a glasshouse experiment Do plants remember drought? Hints towards a drought-memory in grasses