Spinach (Spinacia oleracea L.) varies in tolerance to saturated soil conditions. Plant vigor was assessed for plants flooded in autoclaved and nonautoclaved field soil. Decline of vigor was more rapid for plants flooded in nonautoclaved field soil, indicating that flooding tolerance may be influenced by soil borne pathogens.
Spinach (Spinacia oleracea L.) varies in tolerance to saturated soil conditions. Plant vigor was assessed for plants flooded in autoclaved and nonautoclaved field soil. Decline of vigor was more rapid for plants flooded in nonautoclaved field soil, indicating that flooding tolerance may be influenced by soil borne pathogens.
other abiotic stresses have not been studied. The objective of this experiment was to test the hypothesis that flooding tolerance in citrus trees could be improved by interstocks. We explored the physiological, nutritional, and biochemical responses to
The potential for enhancing flood tolerance of birches by using better adapted rootstock was evaluated. Survival, growth, and physiological responses were compared among flooded and nonflooded container-grown Japanese birch (Betula platyphylla var. japonica Hara. `Whitespire') trees grafted onto each of four rootstock: paper birch (B. papyrifera Marsh), European birch (B.pendula Roth.), river birch (B. nigra L.), and `Whitespire' Japanese birch. Separate studies were conducted in Fall 1991 and Spring 1992. Results showed no consistent differences in net photosynthesis (Pn) or survival among nonflooded plants regardless of rootstock or season, nor, were any symptoms of graft incompatibility evident. Flooding the root system for as long as 44 days revealed considerable differences among the four rootstock, with similar trends for fall and spring. Plants on river birch rootstock typically had one of the highest P rates and stomatal conductance (g,) and, in certain cases, greater mean shoot growth rates and survival of plants subjected to prolonged flooding. Although plants with European birch rootstock had survival rates similar to those of plants with river birch rootstock, plants on European birch rootstock had lower Pn under prolonged flooding, fewer late-formed roots, lower root-tip density after flooding, more abscissed leaves, and greater inhibition of shoot growth of plants flooded the previous fall. Paper and Japanese birch rootstock were most sensitive to flooding and had the lowest survival rate after flooding. However, plants on paper birch rootstock were the only plants whose Pn did not increase significantly when flooding ended; they had the most abscissed leaves during spring flooding and the greatest inhibition of shoot growth in the spring after flooding the previous fall. The four rootstock ranked from most to least flood tolerant were river > European > Japanese > paper.
Abstract
High temperature tended to aggravate injury caused to tomato plants by flooding. Based on plant responses such as chlorosis, epinasty, and wilting, less than 0.2% (8 of 4630 accessions) of the world collection of the garden tomato (Lycopersicon esculentum Mill.) and related Lycopersicon species exhibited some level of tolerance to a short period of flooding associated with high temperature. The level of flood tolerance in one of the 8 flood tolerant accessions, L-123, was found to be less than that of 7 other vegetables tested.
Temperature sensitivity of net photosynthesis (PSN), dark respiration, and chlorophyll fluorescence was evaluated among three taxa of hollies including I. aquifolium, I. cornuta, and I. rugosa. Variations in foliar heat tolerance among these species were expressed as differential temperature responses for PSN. Temperature optima for PSN was 22.0, 26.3 and 27.9 umol·m–2·s–1 for I. rugosa, I. cornuta, and I. aquifolium, respectively. Differences in temperature optima for PSN and thermotolerance of PSN appeared to result from a combination of stomatal and nonstomatal limitations. At 40°C, potential photosynthetic capacity, measured under saturating CO2, was 4.1, 9.4, and 14.8 μmol·m–2·s–1 for I. rugosa, I. aquifolium, and I. cornuta, respectively. Based on these results, I. rugosa was identified as the most heat-sensitive species followed by I. aquifolium then I. cornuta. Comparative tolerance to root-zone inundation was evaluated among 14 holly taxa. Following 8 weeks of flooding, four of the taxa: I. cornuta `Burfordii', I. × `Nellie R. Stevens', I. cassine, and I. × attenuata `Foster's #2' performed remarkably well during and after flooding with photosynthetic rates > 40% of the controls, root ratings >75% of the controls, <5% of the foliage showing deterioration, and 100% survival. Conversely, I. crenata `Convexa', Ilex × meserveae `Blue Princess', I. rugosa and I. aquifolium `Sparkler' did not tolerate flooding well as indicated by severely depressed photosynthetic rates, deterioration of foliage and roots, and decreased survival. The remaining taxa were intermediate.0
The effect of short interval cyclic flooding on root and shoot growth of ‘Shamrock’ inkberry holly (Ilex glabra), ‘Henry's Garnet’ sweetspire (Itea virginica), and ‘Winterthur’ possumhaw (Viburnum nudum) was studied in a greenhouse in Auburn, AL. Liners (4.4 inches long) of each species were planted into trade 1-gal pots in 1 pine bark:1 peat by volume (PB:P) or fine textured calcined clay (CC). ‘Shamrock’ inkberry holly and ‘Henry's Garnet’ sweetspire were planted 18 Apr. 2008; the experiment was repeated with the addition of ‘Winterthur’ possumhaw on 16 June 2008. Plants were flooded to substrate level for 0 (non-flooded), 3, or 7 days. Flooding cycles were repeated at least five times with 7 days of draining between each flood cycle. During draining, plants received no irrigation. Non-flooded plants were watered as needed. Flooded plants for all species except ‘Winterthur’ possumhaw showed decreased root dry weight, shoot dry weight, and final growth index when compared with non-flooded plants. Survival was higher in CC than PB:P for both experiments. All plants maintained good visual quality and shoot growth. As a result, overall, these plants seemed tolerant of flooding despite differences in growth.
Although many species of Alnus Miller grow in wet soils, none is as closely associated with low-oxygen, waterlogged soils as Alnus maritima (Marsh.) Muhl. ex Nutt. (seaside alder). An actinorhizal species with promise for use in horticultural landscapes, land reclamation, and sustainable systems, A. maritima associates with Frankia Brunchorst, thereby forming root nodules in which gaseous nitrogen is fixed. Our objective was to determine how root-zone moisture conditions influence the occurrence, location, and anatomy of nodules on A. maritima. Plants of Alnus maritima subsp. maritima Schrader and Graves were established in root zones with compatible Frankia and subjected to four moisture regimens (daily watered/drained, partially flooded, totally flooded, and totally flooded with argon bubbled through the flood water) for 8 weeks. Oxygen content of the root zone, number and location of nodules on root systems, and dry weight and nitrogen content of shoots were determined. Root-zone oxygen content ranged from 17.3 kPa for daily watered/drained plants to 0.9 kPa for argon-treated plants. Across all treatments, 87% of the nodules were within the upper one-third (4 cm) of the root zone. Although shoot dry weights of daily watered/drained and partially flooded plants were not different, daily watered/drained plants had more nitrogen in their leaves (2.53 vs. 2.21 mg·g-1). Nodulation occurred in all treatments, but nodules on totally flooded roots (with or without argon) were limited to a single lobe; in contrast, multilobed nodules were prevalent on partially flooded and daily watered/drained plants. Frankia infection within submerged nodule lobes was limited to one or two layers of cortical cells. Submerged nodules developed large air spaces between cortical cells, and phenolic-containing cells appeared to inhibit Frankia expansion within the nodule. These data suggest that access to root-zone oxygen is critical to the Frankia-A. maritima subsp. maritima symbiosis, and that plants of this subspecies in the drained soils of managed landscapes may benefit more than plants in native wetland habitats from nodulation and nitrogen fixation.
Since arbuscular–mycorrhizal (AM) fungi are aerobic, symbiosis was not considered significant under flooded conditions. However, AM colonization of wetland plants is now believed more common than previously thought. In the humid tropics, storms that result in standing water for 24 hours or less are common. Short-term floods, especially on sandy soils, may leach banded fertilizer, reducing uptake efficiency. Crops planted in flood prone areas are not normally enhanced with mycorrhizal mixes. However, mycorrhizal associations tolerant to wet conditions may improve nutrient uptake as plants recover from short-term flooding. Greenhouse studies were initiated to determine the effects of frequent short-term floods (two to four events) on mycorrhizal colonization and subsequent development in snap bean (Phaseolus vulgaris
Phaseolus vulgaris L.) plants. Flooding produced no obvious long-term physical effects on plant shoots. In the first study, flooding did not affect survival of colonies established before the first flood event. Percent root colonization in flooded vs. nonflooded treatments was not significantly different at either 31 or 50 days after planting (DAP). As root length increased there was a concomitant increase in colonization so that percent colonization remained approximately the same in both flooded and nonflooded treatments. In the second study, three weekly floods beginning 13 DAP (cotyledon leaf open only) did not inhibit initial mycorrhizal colonization. Mycorrhizal associations should form with snap bean under conditions subject to short-term flooding. Additional research is needed to determine the efficacy of different mycorrhizal mixes under short-term flooded conditions in the field.
effects created by plagiotropic growth form relative to BC and MC and potentially reduced flood tolerance relative to BC. The greater tolerance of BC to flooding may preclude major gains in salt tolerance improvement for use in coastal wetland restoration