scholarly journals Germination response to water availability in populations of Festuca pallescens along a Patagonian rainfall gradient based on hydrotime model parameters

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Aldana S. López ◽  
D. R. López ◽  
M. V. Arana ◽  
D. Batlla ◽  
P. Marchelli
Keyword(s):  
Water Potential ◽  
Water Availability ◽  
Model Parameters ◽  
Species Variation ◽  
Suitable Model ◽  
Rainfall Gradient ◽  
Festuca Pallescens ◽  
Hydrotime Model ◽  
Response To Water ◽  
Base Water Potential

AbstractSensitivity to water availability is a key physiological trait for grassland species located in arid and semiarid environments, where successful germination is closely related to rainfall dynamics. Festuca pallescens inhabits diverse environments along a steep precipitation gradient in North Patagonia, thus offering a suitable model for the study of germination behavior in response to water availability. By analyzing germination in nine populations using a hydrotime model approach, we aimed to find within-species variation. Seed population behavior was analyzed under different hydric conditions using hydrotime model parameters (hydrotime, mean base water potential and its standard deviation). We estimated the mean base water potential for F. pallescens (ψb(50) = − 2.79 ± 0.45 MPa), which did not differ significantly between populations. However, the hydrotime parameter (θH) varied markedly, suggesting physiological adaptation to local environments. Higher values of θH were found in populations located at the extremes of the distribution gradient, indicating that germination may be prevented or delayed in conditions that are suboptimal for the species. Since the variation in hydrotime model parameters did not follow a cline, micro-environmental cues may have the greatest influence on the physiological behavior of the species, rather than the macroscale rainfall gradient.

Hydropriming accelerates seed germination of Medicago sativa under stressful conditions: A thermal and hydrotime model approach

2017 ◽  
Author(s):  
Rong Li ◽  
Dandan Min ◽  
Lijun Chen ◽  
Chunyang Chen ◽  
Xiaowen Hu
Keyword(s):  
Water Potential ◽  
Germination Rate ◽  
High Water ◽  
Nacl Stress ◽  
Base Temperature ◽  
Severe Water Stress ◽  
Hydrotime Model ◽  
Response To Temperature ◽  
Base Water Potential ◽  
Temperature Water

This study determined the effects of priming on germination in response to temperature, water potential and NaCl. Thermal and hydrotime models were utilized to evaluate changes in parameters of the model after priming. Priming reduced the amount of thermal time in both cultivars, but slightly increased the base temperature for germination from 1.0 to 3.5°C in “Longdong”. Priming significantly increased germination rate at high water potential but had no effect at low water potential. Further, priming reduced the hydrotime constant but made the median base water potential value slightly more positive in both cultivars. Thus, priming increased germination rate in water but decrease it under severe water stress. Germination rate was significantly increased in both cultivars under salinity (NaCl) stress. Moreover, priming improved seedling growth in response to temperature, water and salinity stress in both cultivars.

Incubation under fluctuating temperatures reduces mean base water potential for seed germination in several non-cultivated species

2005 ◽  
Vol 15 (2) ◽  
pp. 89-97 ◽  
Author(s):  
Roberto Huarte ◽  
Roberto L. Benech-Arnold
Keyword(s):  
Seed Germination ◽  
Water Potential ◽  
Osmotic Potential ◽  
Quantitative Description ◽  
Maximum Temperature ◽  
The Mean ◽  
Hydrotime Model ◽  
Total Seed ◽  
Base Water Potential ◽  
Fluctuating Temperatures

Seeds ofCarduus acanthoides,Cynara cardunculus,Cirsium vulgare,Brassica campestris, andSisymbrium altissimumwere incubated at a range of decreasing osmotic potentials (Ψo) under fluctuating temperatures or the median temperature of the fluctuation cycle. Fluctuating temperatures promoted total seed germination in water and at reduced osmotic potential. Total germination was reduced as the Ψodecreased. However, this trend was smallest under fluctuating temperatures, signalling a higher tolerance of seeds to reduced osmotic potential. Effects of osmoticum and temperature were modelled with the hydrotime model. The parameters estimated from the model, the hydrotime constant (θH), the mean base water potential Ψb(50) and its standard deviation (σΨb) gave good descriptions of germination time courses. For all species, incubation under fluctuating temperatures shifted Ψb(50) values downwards without modifying their distribution substantially. This accounted for the greater tolerance of germination to reduced Ψounder fluctuating temperatures. To confirm that these effects were mediated by temperature fluctuationsper se, the behaviour ofC. acanthoidesandC. cardunculusincubated at the minimum, the mean and the maximum temperature of the fluctuation cycle was also analysed. Constant maximum and minimum temperatures of the cycle did not stimulate germination, nor did they shift Ψb(50) towards more negative values. The hydrotime model provides a physiologically based quantitative description for germination promotion due to fluctuating temperature.

Application of the hydrotime model to assess seed priming effects on the germination of rapeseed (Brassica napus L.) in response to water stress

Botany ◽  
2020 ◽  
Vol 98 (5) ◽  
pp. 283-291
Author(s):  
Samaneh Tatari ◽  
Farshid Ghaderi-Far ◽  
Ahad Yamchi ◽  
Asieh Siahmarguee ◽  
Ali Shayanfar ◽  
...  
Keyword(s):  
Water Stress ◽  
Germination Rate ◽  
Seed Priming ◽  
Germination Percentage ◽  
The Other ◽  
Dormancy Breaking ◽  
Brassica Napus L ◽  
Hydrotime Model ◽  
Response To Water ◽  
Base Water Potential

Our aim was to determine whether the parameters of the hydrotime model can be used to compare the effects of seed priming treatments on germination. Seeds of three rapeseed cultivars (‘H61’, ‘H4815’, and ‘DK003’) were exposed to priming treatments and then their germination was tested at different water potentials. Seed priming improved the germination percentage, which was higher in ‘H4815’ than in the other two cultivars, and it increased germination rate (decreased θH) and uniformity (decreased σψb). The increase in germination rate was higher in PEG-osmoprimed than in NaCl-osmoprimed and hydroprimed seeds. The base water potential allowing 50% germination ([Formula: see text]) also was affected by seed priming, but the response of cultivars to different priming treatments varied. Compared with the control seeds, hydropriming of ‘H61’ seeds shifted ψb(50) toward negative values, whereas NaCl-osmopriming of ‘H4815’ seeds shifted ψb(50) toward negative values. On the other hand, priming of ‘DK003’ seeds shifted ψb(50) to more positive values and increased susceptibility to water stress. After dormancy-breaking and dormancy-induction treatments, ψb(50) shifted to more negative or positive values, indicating the release of primary dormancy and induction of dormancy, respectively. Therefore, priming treatments should be selected, depending on the environmental conditions anticipated to prevail during the germination of rapeseed seeds.

Seed dormancy in red rice. XII: Population-based analysis of dry-afterripening with a hydrotime model

2007 ◽  
Vol 17 (4) ◽  
pp. 253-271 ◽  
Author(s):  
Alberto Gianinetti ◽  
Marc Alan Cohn
Keyword(s):  
Water Potential ◽  
Germination Rate ◽  
Red Rice ◽  
Decay Kinetics ◽  
Water Potentials ◽  
Secondary Dormancy ◽  
Seed Population ◽  
The Mean ◽  
Hydrotime Model ◽  
Base Water Potential

AbstractRed rice (Oryza sativaL.) dispersal units (florets) were dry-afterripened for 0–8 weeks and subsequently incubated at 30°C in polyethylene glycol (PEG) solutions with water potentials from 0 to − 1.6 MPa. Germination percentages and rates increased with dry-afterripening and water potential of the incubation medium. The seed population exhibited a normal distribution of base water potentials (Ψb, i.e. minimum water potential allowing germination) among individual seeds, characterized by three parameters: the hydrotime constant (θH), the mean base water potential (Ψb) and the standard deviation of the base water potential distribution (σΨb). Changes in germination during afterripening could be described by modifications of such parameters, particularlyΨb, which was employed to derive an index, DH(ARX = Ψb(ARX) − Ψb(ARN), where DH(ARX) represents a measure of dormancy of the seed population (in MPa) based on the hydrotime model,Ψb(ARX) is the mean base water potential of the seed population at any afterripening timeX, andΨb(ARN) is the mean water potential of the non-dormant (fully afterripened) population. The introduction of this index permitted interpretation of afterripening as a measurable reduction in the dormancy status of the seed, with progressive acquisition of both full germinative capacity and maximum germination rate, as anticipated by the hydrotime model. Moreover, secondary dormancy was induced proportionally to the reduction in water potential in the dark. Susceptibility to secondary dormancy induction was defined through DI(ARX), an index analogous to DH(ARX). These indices revealed that, in red rice, both breaking of primary dormancy and the inducibility of secondary dormancy followed decay kinetics with different sensitivities to the duration of dry storage.

scholarly journals The seasonal dormancy pattern and germination of Matricaria maritima subsp. inodora (L.) Dostal seeds in hydrotime model terms

2011 ◽  
Vol 76 (4) ◽  
pp. 299-307 ◽  
Author(s):  
Anna Bochenek ◽  
Janusz Gołaszewski ◽  
Ryszard J. Górecki
Keyword(s):  
Model Parameters ◽  
Life Strategies ◽  
Population Parameters ◽  
Weed Seed ◽  
Natural Conditions ◽  
Pattern Description ◽  
Time Courses ◽  
Hydrotime Model ◽  
Base Water Potential ◽  
Dormancy Pattern

Changes in hydrotime model parameters were determined in <em>Matricaria maritima</em> L. subsp. inodora seeds during burial in a field in order to describe the seasonal dormancy pattern. Seeds were exhumed at regular intervals over a year and incubated at different water potentials at 19°C. Germination time courses were analyzed to determine hydrotime population parameters. Values of ѱb(50), ѲH and σѱb varied each month. Mean base water potential values in seeds exhumed each month were related to precipitation over 20 days before their exhumation. Soil temperature could be a trend-controlling factor of this relationship. The seeds were in deep dormancy after remaining 80-90 days in soil below or above limit temperature 15°C. The application of the hydrotime model to describe and predict seasonal dormancy patterns of weed seed is promising, especially for species with a considerable diversification of life strategies and ecophysiological flexibility of diaspores. It could also suggest mechanisms of seasonal dormancy changes of seeds in natural conditions and provide a basis for their examination. One of advantages of the dormancy pattern description of weed seeds remaining in a soil bank by means of threshold models is its simplicity.

scholarly journals The risk-takers and -avoiders: germination sensitivity to water stress in an arid zone with unpredictable rainfall

AoB Plants ◽  
2019 ◽  
Vol 11 (6) ◽  
Author(s):  
Corrine Duncan ◽  
Nick L Schultz ◽  
Megan K Good ◽  
Wolfgang Lewandrowski ◽  
Simon Cook
Keyword(s):  
Water Stress ◽  
Seed Germination ◽  
Water Potential ◽  
Water Availability ◽  
Cold Climate ◽  
Arid Zones ◽  
Water Potentials ◽  
Risk Takers ◽  
Hydrotime Model ◽  
Germination Traits

Abstract Water availability is a critical driver of population dynamics in arid zones, and plant recruitment is typically episodic in response to rainfall. Understanding species’ germination thresholds is key for conservation and restoration initiatives. Thus, we investigated the role of water availability in the germination traits of keystone species in an arid ecosystem with stochastic rainfall. We measured seed germination responses of five arid species, along gradients of temperature and water potential under controlled laboratory conditions. We then identified the cardinal temperatures and base water potentials for seed germination, and applied the hydrotime model to assess germination responses to water stress. Optimum temperatures for germination ranged from 15 to 31 °C under saturated conditions (0 MPa), and three species had low minimum temperatures for germination (&lt;3 °C). A small proportion of seeds of all species germinated under dry conditions (Ψ ≤ −1 MPa), although base water potential for germination (Ψ b50) ranged from −0.61 to −0.79 MPa. Species adhered to one of two germination traits: (i) the risk-takers which require less moisture availability for germination, and which can germinate over a wider range of temperatures irrespective of water availability (Casuarina pauper and Maireana pyramidata), and (ii) the risk-avoiders which have greater moisture requirements, a preference for cold climate germination, and narrower temperature ranges for germination when water availability is low (Atriplex rhagodioides, Maireana sedifolia and Hakea leucoptera). High seed longevity under physiological stress in H. leucoptera, combined with a risk-avoiding strategy, allows bet-hedging. The hydrotime model predicted lower base water potentials for germination than observed by the data, further supporting our assertion that these species have particular adaptations to avoid germination during drought. This study provides insights into the complex physiological responses of seeds to environmental stress, and relates seed germination traits to community dynamics and restoration in arid zones.

scholarly journals Under pressure: maternal effects promote drought tolerance in progeny seed of Palmer amaranth (Amaranthus palmeri)

Weed Science ◽  
2020 ◽  
pp. 1-8
Author(s):  
Maor Matzrafi ◽  
O. Adewale Osipitan ◽  
Sara Ohadi ◽  
Mohsen B. Mesgaran
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Maternal Effects ◽  
Environmental Conditions ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Hydrotime Model ◽  
Base Water Potential ◽  
Seed Characteristics ◽  
Two Populations

Abstract The environmental conditions under which parental plants are reared can affect the seed characteristics of the progeny. The variation originating from such maternal effects has rarely been incorporated into models of seed germination. Here, using Palmer amaranth (Amaranthus palmeri S. Watson), we examined the effects of water stress during the growth of parental plants on the progeny seed characteristics, including weight, size, final germination, and parameters of a hydrotime germination model. We grew two populations (from California and Kansas) under continuous water-deficit or well-watered conditions. In both A. palmeri populations, progeny seeds originating from water-stressed plants were heavier and larger than those from well-watered plants. Plants exposed to water stress also produced seeds that were ~30% less dormant than seeds from control plants. To test whether the maternal environment affects the parameters of a hydrotime model, progeny seeds were subject to five water potentials (0, −0.2, −0.4, −0.6, and −0.8 MPa) and incubated at 20 and 30 C; germination was monitored daily. The estimated median base water potential (Ψb(50)), that is, the water potential at which 50% of seeds cannot germinate, was consistently lower for seeds from water-stressed plants than for seeds from well-watered plants. Our results showed that A. palmeri plants experiencing drought during their growth produce seeds that are less dormant and can germinate from drier conditions—a maternal response that seems to be adaptive. These findings also call for development of germination models that incorporate the environmental conditions of both the current and past seasons to better describe the variability in germination of weed seeds.

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