Overcoming physical seed dormancy in priority native species for use in arid-zone restoration programs

2016 ◽  
Vol 64 (5) ◽  
pp. 401 ◽  
Author(s):  
Todd E. Erickson ◽  
David J. Merritt ◽  
Shane R. Turner
Keyword(s):  
Native Species ◽  
Arid Zone ◽  
Relative Effectiveness ◽  
Heat Treatments ◽  
Treatment Temperature ◽  
Physical Dormancy ◽  
Dry Heat ◽  
Wet Heat ◽  
Seed Handling ◽  
Species Specific

The relative effectiveness of wet- and dry-heat treatments on alleviating physical dormancy (PY) of seeds of seven species of Fabaceae and five species of Malvaceae was determined to optimise seed handling procedures for ecological restoration. Seeds of all species were treated at different temperatures (40−100°C) for various durations (2 and 5 min of wet heat, and 5, 10 and 30 min of dry heat). Prior to treatment, seeds of all species exhibited low germination (0–38%). As hypothesised, there was variation among species with respect to the efficacy of the heat treatments. In general, wet-heat treatments at temperatures >70°C for 2 or 5 min were effective in breaking PY for all Fabaceae species, and two Malvaceae species, with resultant germination typically >75%. For dry-heat treatments, higher temperatures and longer durations were required to achieve similar germination results. In the three Malvaceae species that were least responsive to heat (Abutilon otocarpum, Hibiscus haynaldii and Sida echinocarpa), there was a trade-off between treatment temperature and duration; lower temperatures (<70°C) failed to alleviate PY, whereas higher temperatures either rendered seeds permeable but not germinable (70−90°C), or resulted in seeds losing viability (e.g. 100°C). Therefore, combinational dormancy (PY + physiological dormancy) appears to be present in a proportion of the seeds of these Malvaceae species (i.e. those that imbibed and remained viable, but did not germinate). Scanning electron imagery established that the majority of wet-heat treatments resulted in the rupture of the water gap in the seed testa of all species. The results clearly demonstrate that optimal heat treatments for the alleviation of PY are species-specific. Restoration practitioners handling seeds of diverse species should be mindful of treating seeds at the lowest effective temperature (70−90°C) to avoid injury through inadvertent exposure to temperatures that are higher and longer than necessary to break dormancy.

Dormancy-breaking and germination requirements for seeds of Acacia papyrocarpa, Acacia oswaldii and Senna artemisioides ssp.×coriacea, three Australian arid-zone Fabaceae species

2014 ◽  
Vol 62 (7) ◽  
pp. 546 ◽  
Author(s):  
Leanne M. Pound ◽  
Phillip J. Ainsley ◽  
José M. Facelli
Keyword(s):  
Arid Zone ◽  
South Australia ◽  
Dormancy Breaking ◽  
Physical Dormancy ◽  
Dry Heat ◽  
Seed Mortality ◽  
Wet Heat ◽  
Pre Treatment ◽  
Unpredictable Environment ◽  
Germination Requirements

Physical dormancy is common in seeds of arid-land legumes. Improved understanding of germination requirements of hard-seeded species will further our understanding of arid lands and aid restoration projects. We studied the germination responses of Acacia papyrocarpa (Benth.), A. oswaldii (F.Muell) and Senna artemisioides (Gaudich. ex DC.) Randell ssp. × coriacea (Benth.) Randell from a chenopod shrubland in South Australia. Imbibition testing indicated that all three species had physical dormancy, but the proportion of dormant seeds was lower in A. oswaldii. This corresponded to a thinner testa in this species. Mechanisms tested to scarify seeds included mechanical scarification and different durations of wet or dry heat. Mechanically scarified seeds germinated readily, reaching maximum numbers in 10–15 days, independently of incubation temperatures, with the exception of S. artemisioides seeds, which germinated at a slower rate in cooler temperatures. Overall, wet heat was more effective than dry heat to alleviate physical dormancy, whereas dry heat in some cases resulted in seed mortality. On the basis of these results, it is recommended that seeds of A. papyrocarpa and S. artemisoides be pretreated with wet heat in future restoration programs. No pre-treatment is required for dormancy loss in A. oswaldii seeds. The different responses of seeds of these species suggest that their populations have varying strategies for persistence in this unpredictable environment.

Cross-species Transcriptomes Reveal Species-specific and Shared Molecular Adaptations for Plants Development on Iron-rich Rocky Outcrops Soils

2021 ◽  
Author(s):  
Mariana Costa Dias ◽  
Cecílio Caldeira ◽  
Markus Gastauer ◽  
Silvio Ramos ◽  
Guilherme Oliveira
Keyword(s):  
Circadian Rhythm ◽  
Differential Expression ◽  
Native Species ◽  
Molecular Mechanisms ◽  
Light Stimulus ◽  
Differential Expression Analysis ◽  
Common Mechanism ◽  
Dependent Manner ◽  
Rocky Outcrops ◽  
Species Specific

Abstract BackgroundCanga is the Brazilian term for the savanna-like vegetation harboring several endemic species on iron-rich rocky outcrops, usually considered for mining activities. Parkia platycephala Benth. and Stryphnodendron pulcherrimum (Willd.) Hochr. naturally occur in the cangas of Serra dos Carajás (eastern Amazonia, Brazil) and the surrounding forest, indicating high phenotypic plasticity. The morphological and physiological mechanisms of the plants’ establishment in the canga environment are well studied, but the molecular adaptative responses are still unknown. We aimed to identify molecular mechanisms that allow the establishment of these plants in the canga environment.ResultsPlants were grown in canga and forest substrates collected in the Carajás Mineral Province. RNA was extracted from pooled leaf tissue, and RNA-seq paired-end reads were assembled into representative transcriptomes for P. platycephala and S. pulcherrimum containing 31,728 and 31,311 primary transcripts, respectively. We identified both species-specific and core molecular responses in plants grown in the canga substrate using differential expression analyses. In the species-specific analysis, we identified 1,112 and 838 differentially expressed genes for P. platycephala and S. pulcherrimum, respectively. Enrichment analyses showed unique biological processes and metabolic pathways affected for each species. Comparative differential expression analysis was based on shared single-copy orthologs. The overall pattern of ortholog expression was species-specific. Even so, almost 300 altered genes were identified between plants in canga and forest substrates, responding the same way in both species. The genes were functionally associated with the response to light stimulus and the circadian rhythm pathway.ConclusionsPlants possess species-specific adaptative responses to cope with the substrates. Our results also suggest that plants adapted to both canga and forest environments can adjust the circadian rhythm in a substrate-dependent manner. The circadian clock gene modulation might be a central mechanism regulating the plants’ development in the canga substrate in the studied legume species. The mechanism may be shared as a common mechanism to abiotic stress compensation in other native species.

scholarly journals Emerging fungal pathogen of an invasive grass: Implications for competition with native plant species

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0237894
Author(s):  
Amy E. Kendig ◽  
Vida J. Svahnström ◽  
Ashish Adhikari ◽  
Philip F. Harmon ◽  
S. Luke Flory
Keyword(s):  
Invasive Species ◽  
Plant Species ◽  
Fungal Pathogen ◽  
Native Species ◽  
Grass Species ◽  
Leaf Spot Disease ◽  
Native Plant ◽  
Invasive Grass ◽  
Native Plant Species ◽  
Species Specific

Infectious diseases and invasive species can be strong drivers of biological systems that may interact to shift plant community composition. For example, disease can modify resource competition between invasive and native species. Invasive species tend to interact with a diversity of native species, and it is unclear how native species differ in response to disease-mediated competition with invasive species. Here, we quantified the biomass responses of three native North American grass species (Dichanthelium clandestinum, Elymus virginicus, and Eragrostis spectabilis) to disease-mediated competition with the non-native invasive grass Microstegium vimineum. The foliar fungal pathogen Bipolaris gigantea has recently emerged in Microstegium populations, causing a leaf spot disease that reduces Microstegium biomass and seed production. In a greenhouse experiment, we examined the effects of B. gigantea inoculation on two components of competitive ability for each native species: growth in the absence of competition and biomass responses to increasing densities of Microstegium. Bipolaris gigantea inoculation affected each of the three native species in unique ways, by increasing (Dichanthelium), decreasing (Elymus), or not changing (Eragrostis) their growth in the absence of competition relative to mock inoculation. Bipolaris gigantea inoculation did not, however, affect Microstegium biomass or mediate the effect of Microstegium density on native plant biomass. Thus, B. gigantea had species-specific effects on native plant competition with Microstegium through species-specific biomass responses to B. gigantea inoculation, but not through modified responses to Microstegium density. Our results suggest that disease may uniquely modify competitive interactions between invasive and native plants for different native plant species.

Thermal Processing of Polycrystalline NiTi Shape Memory Alloys

2004 ◽  
Vol 855 ◽  
Author(s):  
Carl P. Frick ◽  
Alicia M. Ortega ◽  
Jeff Tyber ◽  
Ken Gall ◽  
Hans J. Maier ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Shape Memory ◽  
Hot Rolling ◽  
Rolling Process ◽  
Heat Treatments ◽  
Treatment Temperature ◽  
Precipitate Size ◽  
Stress Strain ◽  
Transformation Temperatures ◽  
Strain Behavior

ABSTRACTThe objective of this study is to examine the effect of heat treatment on polycrystalline Ti-50.9 at.%Ni subsequent to hot-rolling. In particular we examine microstructure, transformation temperatures and mechanical behavior of deformation processed NiTi. The results constitute a fundamental understanding of the effect of heat treatment on thermal/stress induced martensite, which is critical for optimizing mechanical properties. The high temperature of the hot-rolling process caused recrystallization, recovery, and hindered precipitate formation, essentially solutionizing the NiTi. Subsequent heat treatments were carried out at various temperatures for 1.5 hours. Transmission Electron Microscopy (TEM) observations revealed that Ti3Ni4 precipitates progressively increased in size and changed their interface with the matrix from being coherent to incoherent with increasing heat treatment temperature. Accompanying the changes in precipitate size and interface coherency, transformation temperatures were observed to systematically shift, leading to the occurrence of the R-phase and multiple-stage transformations. Room temperature stress-strain tests illustrated a variety of mechanical responses for the various heat treatments, from pseudoelasticity to shape memory. The changes in stress-strain behavior are interpreted in terms of shifts in the primary martensite transformation temperatures, rather then the occurrence of the R-phase transformation. The results confirm that Ti3Ni4 precipitates can be used to elicit a desired isothermal stress-strain behavior in polycrystalline NiTi.

Some effects of heat waves on grain sorghum at the stage of head emergence

1969 ◽  
Vol 9 (41) ◽  
pp. 636 ◽  
Author(s):  
D Pasternak ◽  
GL Wilson
Keyword(s):  
High Temperature ◽  
Grain Yield ◽  
Seed Set ◽  
Heat Waves ◽  
Pollen Viability ◽  
Grain Sorghum ◽  
Heat Treatments ◽  
Grain Production ◽  
Dry Heat ◽  
Heat Application

Sorghum plants were exposed at head emergence to simulated heat waves for five days, and subsequent grain production observed. Comparisons were made between relatively dry heat (108�F, 41 per cent RH by day and 90�F, 53 per cent RH by night), more humid hot conditions (107�F, 70 per cent RH-90�F, 70 per cent RH), and ambient (81�F, 64 per cent RH-71�F, 85 per cent RH). Whole inflorescences or portions that had emerged before heat application were little affected, whereas most enclosed flowers were killed. High temperature was responsible, humidity having little effect. Grain yield depended on the resulting number of grains. There was some loss of pollen viability in the dry heat treatments, but not sufficient to affect seed set.

scholarly journals In-Situ Characterization by High-Energy X-ray Diffraction of the Phase Transformations Leading to Transformation-Induced Plasticity-Aided Bainitic Steel

2019 ◽  
Vol 3 (4) ◽  
pp. 25
Author(s):  
Zélie Tournoud ◽  
Frédéric De Geuser ◽  
Gilles Renou ◽  
Didier Huin ◽  
Patricia Donnadieu ◽  
...  
Keyword(s):  
Carbon Content ◽  
Phase Transformations ◽  
High Energy ◽  
Heat Treatments ◽  
Treatment Temperature ◽  
Bainitic Steel ◽  
X Ray Diffraction ◽  
Transformation Induced Plasticity ◽  
X Ray

The phase transformations occurring during the heat treatments leading to transformation-induced plasticity (TRIP)-aided bainitic steel have been investigated in-situ by high-energy X-ray diffraction (HEXRD) conducted with synchrotron light at 90 keV. Direct microstructure characterization has been performed by electron microscopy using electron backscatter diffraction and orientation and phase mapping in a transmission electron microscope. HEXRD data allow the quantification of the evolution of the austenite phase fraction with the heat treatments, as well as its carbon content and the fraction of carbides, from the lattice parameter evolution. It is shown that different combinations of austenite fraction and carbon content can be reached by adjusting the heat treatment temperature.

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