Effect of waterlogging and soil pH on the micro-distribution of naturalised annual legumes

1997 ◽  
Vol 48 (2) ◽  
pp. 223 ◽  
Author(s):  
M. R. Gibberd ◽  
P. S. Cocks

Variation in the size and composition of the soil seed bank of 3 naturalised legumes, subterranean clover (Trifolium subterraneum L.), woolly clover (T. tomentosum L.), and cluster clover (T. glomeratum L.), was related to soil characteristics on a transect that ascended from a winter waterlogged area in a wheatbelt pasture. Growth of the 3 species was compared with other species from section Vesicaria (T. resupinatum and T. clusii) in waterlogged and freely drained pots for 34 days. Of the 3 naturalised legumes present in the transect, cluster clover was rare, and woolly and subterranean clovers were separated on the basis of their response to soil pH and the likelihood of winter waterlogging. Subterranean clover was absent from soil with pH > 7·0; these areas were dominated by woolly clover. Areas with pH < 7·0 were dominated by subterranean clover, except where winter waterlogging was likely, in which case they were once again dominated by woolly clover. The waterlogging tolerance of woolly clover, together with that of other species in section Vesicaria, was confirmed in the pot experiment. After 34 days, shoot dry weight of the waterlogged Vesicaria species was an average of 39% greater than the freely drained controls. Root length continued to increase for the duration of the waterlogging treatment with much of the new root growth as laterals. Conversely, shoot and root growth in subterranean and cluster clovers was severely reduced by waterlogging. The patchy distribution of woolly clover in many wheatbelt pastures can be explained by its response to high pH and winter waterlogging compared with subterranean clover.

1981 ◽  
Vol 32 (2) ◽  
pp. 257 ◽  
Author(s):  
DJ Reuter ◽  
AD Robson ◽  
JF Loneragan ◽  
DJ Tranthim-Fryer

Effects of severe and moderate copper deficiency on the development of leaves and lateral branches, on the distribution of dry weight within the plant, and on seed yield of Seaton Park subterranean clover were assessed as part of three glasshouse experiments. Copper deficiency markedly depressed top and root growth without producing any distinctive symptoms. It retarded phasic development by delaying development of leaves and lateral branches, senescence of plant parts, and flowering: it also depressed the proportion of stem plus petiole in plant tops and decreased internode elongation, pollen fertility and the number of burrs and seeds formed. As a result of its effect in delaying flowering, copper deficiency would depress seed production particularly strongly when low soil water supply shortens the growing season. The need for suitable procedures for diagnosing copper deficiency is emphasized by the lack of specific plant symptoms in this species.


2021 ◽  
Author(s):  
Gereltsetseg Enkhbat ◽  
Megan H. Ryan ◽  
Phillip G. H. Nichols ◽  
Kevin J. Foster ◽  
Yoshiaki Inukai ◽  
...  

Abstract Background and AimsIn the annual pasture legume Trifolium subterraneum, ssp. yanninicum exhibits higher waterlogging tolerance than ssp. brachycalycinum and ssp. subterraneum. This study investigates waterlogging tolerance within ssp. yanninicum ecotypes and explores correlations with seedling phenotypic traits and site of origin eco-geographic variables.MethodsTwenty eight diverse ssp. yanninicum ecotypes collected from the Mediterranean region and four cultivars were grown in a controlled environment glasshouse. After 14 days of growth seedling traits were measured. After 21 days of growth, free-drained (control) and waterlogged treatments were imposed for 28 days. Eco-geographic variables were generated from ‘WorldClim’ using collection site locations.ResultsUnder waterlogging, shoot relative growth rate (RGR) ranged from 87–108% and root RGR ranged from 80–116% of controls. Waterlogging reduced shoot dry weight (DW) in four of 32 genotypes, while root DW was reduced in 13 genotypes. Leaf size was maintained, or even increased, under waterlogging in 31 genotypes. However, petiole length was more affected by waterlogging and has value as a waterlogging tolerance indicator. Waterlogging tolerance was not significantly correlated with seedling DW, flowering time or precipitation at the site of origin, while shoot growth under waterlogging had a positive correlation with summer temperatures at origin.ConclusionsGenotypes of ssp. yanninicum tolerated transient waterlogging and greater tolerance was observed among ecotypes, rather than cultivars. An easy-to-measure indicator of tolerance was found in petiole length reduction. This study highlights untapped genotypic variability for breeders to improve the productivity and persistence of ssp. yanninicum under waterlogging.


1956 ◽  
Vol 7 (2) ◽  
pp. 98 ◽  
Author(s):  
JN Black

Changes in the pre-emergence distribution of dry matter in subterranean clover (Trifolium subterraneum L.) variety Bacchus Marsh were followed at 21°C, using three sizes of seed and three depths of sowing, ½, 1¼, and 2 in. Decreasing seed size and increasing depth of sowing both reduce the weight of the cotyledons a t emergence. Seed of the three sizes were sown a t three depths in pot culture a t staggered intervals so that emergence was simultaneous. Dry weight in the early vegetative stage was proportional to seed size, and total leaf area and leaf numbers showed similar trends. Plants of each seed size grew at the same relative rate. No effect of depth of sowing could be detected, and this was shown to be due to the cotyledon area a t emergence being constant for any given seed size, regardless of varying depth of sowing and hence of cotyledon weight. It was concluded that seed size in a plant having epigeal germination and without endosperm is of importance: firstly, in limiting the maximum hypocotyl elongation and hence depth of sowing, and secondly, in determining cotyledon area. Cotyledon area in turn influences seedling growth, which is not affected by cotyledon weight. Once emergence has taken place, cotyledonary reserves are of no further significance in the growth of the plants.


2015 ◽  
Vol 33 (3) ◽  
pp. 137-141
Author(s):  
Bruce R. Roberts ◽  
Chris Wolverton ◽  
Samantha West

The efficacy of treating soilless substrate with a commercial humectant was tested as a means of suppressing drought stress in 4-week-old container-grown Zinnia elegans Jacq. ‘Thumbelina’. The humectant was applied as a substrate amendment at concentrations of 0.0, 0.8, 1.6 and 3.2% by volume prior to withholding irrigation. An untreated, well-watered control was also included. The substrate of treated plants was allowed to dry until the foliage wilted, at which time the plants were harvested and the following measurements taken: number of days to wilt (DTW), xylem water potential (ψx), shoot growth (shoot dry weight, leaf area) and root growth (length, diameter, surface area, volume, dry weight). For drought-stressed plants grown in humectant-treated substrate at concentrations of 1.6 and 3.2%, DTW increased 25 and 33%, respectively. A linear decrease in ψx was observed as the concentration of humectant increased from 0.0 to 3.2%. Linear trends were also noted for both volumetric moisture content (positive) and evapotranspiration (negative) as the concentration of humectant increased. For non-irrigated, untreated plants, stress inhibited shoot growth more than root growth, resulting in a lower root:shoot ratio. For non-irrigated, humectant-treated plants, the length of fine, water-absorbing roots increased linearly as humectant concentration increased from 0.0 to 3.2%. Using humectant-amended substrates may be a management option for mitigating the symptoms of drought stress during the production of container-grown bedding plants such as Z. elegans.


1991 ◽  
Vol 5 (4) ◽  
pp. 805-810 ◽  
Author(s):  
Michael J. Horak ◽  
Loyd M. Wax

Growth and development of bigroot morningglory was observed and quantified. Emergence occurred 75 ± 5 growing degree days (GDD) after seeding. Flower and seed production began 630 ± 20 GDD after emergence and continued until the first frost killed the shoots. Seedlings needed approximately 460 GDD of growth to become perennial. In the second year of growth, plants emerged in early May and flowered within 425 ± 50 GDD. Shoot dry weight accumulation in first-year plants was 3.5 g for the first 600 GDD after which a fifteenfold increase in dry weight occurred. Root growth followed the same pattern, however the large increase in dry weight occurred approximately 300 GDD later than that of the shoots. The root:shoot ratio was 0.2 to 0.3 for the first 900 GDD and increased to greater than 1.0 by the final harvest.


mSphere ◽  
2020 ◽  
Vol 5 (4) ◽  
Author(s):  
Dario X. Ramirez-Villacis ◽  
Omri M. Finkel ◽  
Isai Salas-González ◽  
Connor R. Fitzpatrick ◽  
Jeffery L. Dangl ◽  
...  

ABSTRACT Glyphosate is a commonly used herbicide with a broad action spectrum. However, at sublethal doses, glyphosate can induce plant growth, a phenomenon known as hormesis. Most glyphosate hormesis studies have been performed under microbe-free or reduced-microbial-diversity conditions; only a few were performed in open systems or agricultural fields, which include a higher diversity of soil microorganisms. Here, we investigated how microbes affect the hormesis induced by low doses of glyphosate. To this end, we used Arabidopsis thaliana and a well-characterized synthetic bacterial community of 185 strains (SynCom) that mimics the root-associated microbiome of Arabidopsis. We found that a dose of 3.6 × 10−6 g acid equivalent/liter (low dose of glyphosate, or LDG) produced an ∼14% increase in the shoot dry weight (i.e., hormesis) of uninoculated plants. Unexpectedly, in plants inoculated with the SynCom, LDG reduced shoot dry weight by ∼17%. We found that LDG enriched two Firmicutes and two Burkholderia strains in the roots. These specific strains are known to act as root growth inhibitors (RGI) in monoassociation assays. We tested the link between RGI and shoot dry weight reduction in LDG by assembling a new synthetic community lacking RGI strains. Dropping RGI strains out of the community restored growth induction by LDG. Finally, we showed that individual RGI strains from a few specific phyla were sufficient to switch the response to LDG from growth promotion to growth inhibition. Our results indicate that glyphosate hormesis was completely dependent on the root microbiome composition, specifically on the presence of root growth inhibitor strains. IMPORTANCE Since the introduction of glyphosate-resistant crops, glyphosate has become the most common and widely used herbicide around the world. Due to its intensive use and ability to bind to soil particles, it can be found at low concentrations in the environment. The effect of these remnants of glyphosate in plants has not been broadly studied; however, glyphosate 1,000 to 100,000 times less concentrated than the recommended field dose promoted growth in several species in laboratory and greenhouse experiments. However, this effect is rarely observed in agricultural fields, where complex communities of microbes have a central role in the way plants respond to external cues. Our study reveals how root-associated bacteria modulate the responses of Arabidopsis to low doses of glyphosate, shifting between growth promotion and growth inhibition.


1963 ◽  
Vol 14 (2) ◽  
pp. 206 ◽  
Author(s):  
JN Black

This paper describes two experiments analysing the recovery from defoliation of subterranean clover varieties grown in swards in large seed boxes at the Waite Agricultural Research Institute, Adelaide. The first experiment examined the way in which the six common commercial varieties recovered from a single severe defoliation, and showed that under these conditions they can be placed in three groups: Yarloop and Clare are tall, high-yielding varieties with few, large leaves, recovering slowly from defoliation; Tallarook and Dwalganup are prostrate varieties, lower-yielding, with many small leaves, recovering rapidly after defoliation; Bacchus Marsh and Mount Barker are intermediate in all respects. In the second experiment mixed swards of equal numbers of Yarloop and Tallarook plants were grown under three treatments: A, no defoliation; B, defoliated twice at a height which removed the higher Yarloop canopy but left the lower Tallarook plants untouched; C, defoliated twice at a height which removed the canopies of both varieties. Measurement of dry weight on four occasions after each defoliation showed that in the undefoliated treatment, all Tallarook plants died by the end of the experiment. In the defoliated treatments, the removal of the Yarloop canopy resulted in only a temporary improvement in the illuniination in which the Tallarook plants grew, and their dry weight and plant numbers progressively declined. Dry weight changes in the Tallarook component were shown to be dependent on the light energy available to it, which was in turn determined by the light-absorbing capacity of the superior Yarloop canopy. In mixed swards, the ability of Yarloop to re-establish quickly a leaf canopy above that of Tallarook appeared to explain its success when defoliated.


1960 ◽  
Vol 11 (3) ◽  
pp. 277 ◽  
Author(s):  
JN Black

Three strains of subterranean clover differing in leaf development were grown in pure swards and in all combinations in mixtures. The strain Yarloop has relatively few large leaves held on long petioles; Tallarook has many small leaves and short petioles; Bacchus Marsh is intermediate in all these respects. The swards were grown in boxes and were sampled on four occasions during the period of vegetative growth. Leaf area in each 2 cm layer of the sward was determined separately, and for both strains in the mixed swards, and measurements of the light intensity reaching each layer were obtained. Root weights were determined for all swards and separately for each component of the mixed swards. Examination of the dry weights showed that the growth of the strain having the lesser petiole elongation was suppressed. In the extreme instance Tallarook was so suppressed when grown with Yarloop that in the final inter-sampling period it grew completely in the dark, and lost about half its dry weight. Bacchus Marsh also suppressed Tallarook, but to a lesser extent, while Bacchus Marsh was itself suppressed in competition with Yarloop. The amount of light energy intercepted by the two components of the mixed swards was calculated from the leaf area and light profiles, and confirmed the importance of the spatial distribution of leaves in plant competition. It was concluded that, in the absence of defoliation, the success of a strain under competition was associated with its potential petiole elongation.


1992 ◽  
Vol 43 (7) ◽  
pp. 1597 ◽  
Author(s):  
JM Wroth ◽  
RAC Jones

In 1989 and 1990, infection with subterranean clover mottle sobemovirus (SCMV) was widespread in subterranean clover ( Trifolium subterraneum L.) pastures in the south-west of Western Australia. The virus was detected in 61% of the pastures sampled and incidences of infection ranged from 1 to 50%. The virus was more common in old pastures than in pastures resown with newer cultivars during the preceeding 5 year period. When 12 isolates of SCMV were inoculated to subterranean clover plants grown in the glasshouse, symptoms varied from mild to severe. SCMV isolates P23 and F4 decreased the herbage dry weight of cw. Daliak and Woogenellup grown in plots as spaced plants by 81-88% while the Type isolate caused losses of 92%. By contrast, losses were 37-49% with cv. Karridale, a cultivar in which systemic infection was either delayed or prevented during winter. Infection decreased seed yield by c. 90% in cvv. Karridale and Woogenellup with all three isolates; seed weight was decreased 21-55%. A small proportion of cv. Woogenellup transplants outgrew the infection in new shoots during late spring to produce abundant healthy foliage. SCMV seed transmission rates in seed collected from infected transplants of cv. Woogenellup were 0.06, 0.07 and 0.43% for the Type, P23 and F4 isolates respectively. It was concluded that SCMV was present in most pastures, but at low incidences, and that it persists in them from year to year. Extended growing seasons and hard grazing are likely to increase its incidence.


FLORESTA ◽  
2018 ◽  
Vol 48 (4) ◽  
pp. 573 ◽  
Author(s):  
Camila Adaime Gabriel ◽  
Paulo Cezar Cassol ◽  
Marcia Aparecida Simonete ◽  
Letícia Moro ◽  
Priscylla Pfleger ◽  
...  

Eucalyptus crops in Southern Brazil are generally conducted in acidic soils, thus their yield can be increased by lime and gypsum applications. The objective of this study was to evaluate the effect of lime and gypsum applications on soil chemical attributes and initial growth of Eucalyptus benthamii and Eucalyptus dunnii in a Humic Cambisol (Inceptisol). The experiment was conducted in a greenhouse, with seedlings of both species of eucalyptus grown in soil treated with different rates of lime (0, 3, 6, and 12 Mg ha-1), and gypsum (0, 6, 3, 12.6, and 25.2 Mg ha-1). At 90 days after application of the treatments, the soil chemical attributes and growth components of eucalyptus seedlings. The lime increased the production shoot dry weight, however, the response to gypsum was negative. The lime increased the soil pH, exchangeable calcium (Ca), base saturation (V %), and slightly the soil electrical conductivity, decreased the soil aluminium saturation (m %), and promoted little reduction in the exchangeable potassium (K) and magnesium (Mg) contents. The gypsum didn't alter the soil pH, but decreased the m%, increased soil phosphorus (P) contents, and expressively increased the electrical conductivity, which may have had a negative effect on the eucalyptus growth. In conclusion, the addition of limestone decreases the soil acidity and benefits the growth of eucalyptus seedlings. However, the addition of gypsum has no expressive effects upon those variables, but it can decrease the growth of seedlings when the rates are excessive.


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