Assessing tree germination resilience to global warming: a manipulative experiment using sugar maple (Acer saccharum)

AbstractA climate warming of 2–5°C by the end of the century will impact the likelihood of seed germination of sugar maple (Acer saccharum), a dominant tree species which possesses a restricted temperature range to ensure successful reproduction. We hypothesize that seed origin affects germination due to the species' local adaptation to temperature. We tested this by experimentally investigating the effect of incubation temperature and temperature shifting on sugar maple seed germination from seven different seed sources representing the current species range. Survival analysis showed that seeds from the northern range had the highest germination percentage, while the southern range had the lowest. The mean germination percentage under constant temperatures was best when temperatures were ≤5°C, whereas germination percentages plummeted at temperatures ≥11°C (5.8%). Cool shifting increased germination by 19.1% over constant temperature treatments and by 29.3% over warm shifting treatments. Both shifting treatments caused earlier germination relative to the constant temperature treatments. A climate warming of up to +5°C is shown to severely reduce germination of seeds from the southern range. However, under a more pronounced warming of 7°C, seed germination at the northern range become more affected and now comparable to those found from the southern range. This study states that the high seed germination percentage found in sugar maple at the northern range makes it fairly resilient to the warmest projected temperature increase for the next century. These findings provide forest managers with the necessary information to make accurate projections when considering strategies for future regeneration while also considering climate warming.

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Temperature Requirements for Seed Germination of Three Penstemon Species'

HortScience ◽

10.21273/hortsci.25.2.191 ◽

1990 ◽

Vol 25 (2) ◽

pp. 191-193 ◽

Cited By ~ 9

Author(s):

Phil S. Allen ◽

Susan E. Meyer

Keyword(s):

Seed Germination ◽

Incubation Temperature ◽

Marked Decrease ◽

Rocky Mountain ◽

Germination Percentage ◽

Cold Stratification ◽

Dormancy Breaking ◽

Primary Dormancy ◽

Temperature Requirements ◽

Seed Propagation

To determine optimum germination temperatures and effective dormancy-breaking procedures, field-grown (1983-85) seeds of `Bandera' Rocky Mountain penstemon (Penstemon strictus Benth), `Cedar' Palmer penstemon (Penstemon palmeri Gray), and firecracker penstemon (Penstemon eatonii Gray) were subjected to various cold stratification and incubation temperature treatments. Increased germination following an 8-week stratification occurred in seed lots containing dormant seeds, but a 2-week stratification generally failed to break dormancy. Older (1983) seeds of `Bandera' and `Cedar' penstemon germinated to full viability without stratification. All species showed a marked decrease in germination percentage above 20C; 15C consistently produced maximum germination after 4 weeks. At 15C, mean times to 90% of total germination were 11, 22, and 29 days for `Bandera', `Cedar', and firecracker penstemon, respectively. Transfer of seeds failing to germinate at warm temperatures (25 and 30C) to 15C and applying 720 μm gibberellic acid (GA3) solution was effective in breaking primary dormancy of firecracker penstemon and secondary dormancy of `Bandera' penstemon. Our findings suggest that incubation below 20C, combined with 8 weeks of stratification or the use of after-ripened seed, may improve seed propagation efforts for these species.

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Petroleum Ether Separation and Seedcoat Removal Enhance Seed Germination of a Casuarina equisetifolia L. × C. glauca Sieb. ex Spreng Hybrid

HortScience ◽

10.21273/hortsci.44.3.770 ◽

2009 ◽

Vol 44 (3) ◽

pp. 770-773

Author(s):

Xiuli Shen ◽

William S. Castle ◽

Frederick G. Gmitter

Keyword(s):

Seed Germination ◽

Petroleum Ether ◽

Germination Percentage ◽

Seed Sources ◽

Citrus Groves ◽

Casuarina Cunninghamiana ◽

Poor Seed ◽

Hybrid Seeds ◽

Two Temperatures ◽

Empty Seeds

Casuarina cunninghamiana Miq. is an introduced species to Florida that has potential as a windbreak plant to help manage canker in citrus groves; however, only Florida sources can be used for that purpose. Local sources of Casuarina are generally adequate seed producers, but germination percentages are frequently poor. Thus, the causes of low seed germination and methods to improve germination were investigated using C. cunninghamiana and a local hybrid (C. equisetifolia L. × C. glauca Sieb. ex Spreng.). Seeds of the hybrid were larger and heavier (88 mg/100 seeds) than those of C. cunninghamiana (mean wt. 67 mg/100 seeds). Shrunken, insect-damaged, and empty seeds, present in all unsorted seed lots, were responsible for poor seed germination of the four seed sources studied. Petroleum ether separation improved germination by dividing seeds into floaters and sinkers. The floater fraction consisted of 47.5% to 93% insect-damaged seeds compared with 9.0% to 43.5% among sinkers. More than 50% of the sinkers were filled seeds and less than 21% in floaters. No empty seeds were sinkers except for one source of C. cunninghamiana. In sorted hybrid seeds, petroleum ether separation eliminated a large proportion of ungerminable seeds (floaters) and seed germination among sinkers was faster with a higher germination percentage than floaters. Cumulative germination of hybrid seeds in a trial involving two temperatures was 23.0% for sunken seeds at 30 °C at the end of 8 weeks compared with 1% of unsorted seeds. Temperature had no significant effect on seed germination. The germination percentage of hybrid seeds with seedcoats removed was 91.0% in the first week of culture compared with only 1.2% in the first week and 12.6% seed germination at the end of 8 weeks' culture of intact seeds.

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Seed Source and Quality Influence Germination in Purple Coneflower [Echinacea purpurea (L.) Moench.]

HortScience ◽

10.21273/hortsci.29.12.1443 ◽

1994 ◽

Vol 29 (12) ◽

pp. 1443-1444 ◽

Cited By ~ 7

Author(s):

N. Wartidiningsih ◽

R.L. Geneve

Keyword(s):

Seed Germination ◽

Dry Weight ◽

Echinacea Purpurea ◽

Germination Percentage ◽

Physiological Maturity ◽

Seed Sources ◽

Purple Coneflower ◽

Temperature Regimes ◽

Two Temperature ◽

Effect Of Light

Six seed lots of purple coneflower were purchased from four commercial seed sources and evaluated for germination in either light or darkness in combination with two temperature regimes (constant 27C vs. alternating 30C for 8 hours and 20C for 16 hours). Seed lot differences accounted for the majority of variation, with two seed lots exhibiting high (81% to 91%) germination and the remaining seed lots having 39% to 66% germination. There was no effect of light on germination, regardless of the seed lot. However, alternating temperatures improved germination in one of the low-germination seed lots. Seed size and inflorescence position did not affect seed germination. Seed harvested at physiological maturity (maximum seed dry weight), but before drying had occurred, had a higher germination percentage than seeds harvested after desiccation, and they maintained a higher germination percentage even after 1 year in storage.

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Bromus tectorum seed germination: between-population and between-year variation

Canadian Journal of Botany ◽

10.1139/b96-109 ◽

1996 ◽

Vol 74 (6) ◽

pp. 875-882 ◽

Cited By ~ 52

Author(s):

Julie Beckstead ◽

Susan E. Meyer ◽

Phil S. Allen

Keyword(s):

Seed Germination ◽

Bromus Tectorum ◽

Incubation Temperature ◽

Weather Conditions ◽

Germination Percentage ◽

Maximum Temperature ◽

Germination Time ◽

Germination Response ◽

Mean Germination Time ◽

Contrasting Habitats

Cheatgrass (Bromus tectorum L., Poaceae), an introduced winter annual, has invaded a variety of habitats in western North America. This study examines variation in cheatgrass germination response and after-ripening patterns that are related to differences in habitat and to yearly differences in weather conditions during seed maturation. Seeds collected from five contrasting populations in 1992 and 1993 were subjected to controlled dry storage and then incubated across a range of temperatures. Recently harvested seeds were dormant and germinated slowly, while fully after-ripened seeds were nondormant and germinated rapidly. The optimal incubation temperature for mean germination time shifted from 5:15 to 20:30 °C as a result of after-ripening. Between-population differences in germination response appear to be related to the potential risk of precocious summer germination. The results from this 2-year study suggest that the more extreme yet predictable environments select for seed germination and after-ripening patterns that are genetically fixed, while populations from more favorable environments tended to show more between-year variations, suggesting more phenotypic plasticity. Germination percentage showed greater between-year variation than mean germination time. Between-year differences could not be explained simply by differences in maximum temperature or total precipitation during maturation. Adaptive germination responses in cheatgrass populations from contrasting habitats may have both genetic and environmental components, thus explaining why this species can become established in such a variety of habitats. Keywords: after-ripening, invading species, dormancy, mean germination time, cheatgrass, downy brome.

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Pericarp, Leachate, and Carbohydrate Involvement in Thermoinhibition of Germinating Spinach Seeds

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.124.3.301 ◽

1999 ◽

Vol 124 (3) ◽

pp. 301-306 ◽

Cited By ~ 12

Author(s):

Daniel I. Leskovar ◽

Virgil Esensee ◽

Helen Belefant-Miller

Keyword(s):

Seed Germination ◽

Constant Temperature ◽

Spinacia Oleracea ◽

Germination Percentage ◽

Germination Inhibition ◽

Physical Barrier ◽

Glucose Levels ◽

Incubation Temperatures ◽

Aba Content ◽

Genotype Sensitivity

Spinach (Spinacia oleracea L.) seed germination can be inhibited by high temperatures. An understanding of thermoinhibition in spinach is critical in predicting germination and emergence events. The purpose of this study was 3-fold: 1) to determine seed germination percentage and rate of spinach genotypes—`Cascade', `ACX 5044', `Fall Green', and `ARK 88-354'—exposed to constant and alternating temperatures; 2) to determine the nature and extent of inhibition imposed by the pericarp; and 3) to investigate leachate and oligosaccharide involvement in thermoinhibition. Germination inhibition began at >20 °C constant temperature and was totally suppressed at 35 °C. Alternating temperatures at 30/15 °C (12-hour day/12-hour night) resulted in greater germination than a constant 30 °C. The genotype sensitivity to supraoptimal temperatures was in the order of `ARK 88-354' ≤ `Fall Green' < `ACX 5044' < `Cascade', but the highly thermoinhibited `Cascade' seeds retained the ability to germinate when shifted to lower incubation temperatures. The pericarp inhibited germination, since seeds deprived of the pericarp had ≈90% germination at 30 °C. `ACX 5044' and `Cascade' had higher ABA content in the pericarp than `ARK 88-354' and `Fall Green'. Before imbibition at 30 °C, raffinose levels in each genotype were in the order of `ARK 88-354' > `Fall Green' > `Cascade'. After 48 hours of imbibition, sucrose and glucose levels were highest and raffinose levels were lowest in `ARK 88-354' and `Fall Green' seeds, while `Cascade' seeds remained less active metabolically. These data suggest that the pericarp apparently acts as a physical barrier as well as a source of inhibitors during thermoinhibition.

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Effect of Potassium Nitrate Priming on Seed Germination of Seashore Paspalum

HortScience ◽

10.21273/hortsci.43.7.2259 ◽

2008 ◽

Vol 43 (7) ◽

pp. 2259-2262 ◽

Cited By ~ 17

Author(s):

Sang In Shim ◽

Jun-Cheol Moon ◽

Cheol Seong Jang ◽

Paul Raymer ◽

Wook Kim

Keyword(s):

Seed Germination ◽

Constant Temperature ◽

Critical Factor ◽

Potassium Nitrate ◽

Germination Percentage ◽

Seashore Paspalum ◽

Second Stage ◽

Priming Condition ◽

Osmotic Solution ◽

Alternating Temperature

Germination of seashore paspalum (Paspalum vaginatum Swartz) is a critical factor influencing seedling establishment when seeded directly in fields. In this research, pregermination priming with osmotic solution was used to improve the germination percentage of seashore paspalum. The goal of this study was to develop techniques that improve the germination of a seashore paspalum cultivar (SeaSpray). Seeds were subjected to priming in petri dishes with solutions of KNO3 at 25 °C for 24, 48, and 72 h in growth chambers. Germination percentage differed by priming duration as well as concentration of priming media. Based on the germination percentage 14 days after imbibition, the most promising priming condition was the treatment with 0.2% or 0.5% KNO3 for 72 h at a constant temperature of 30 °C and 0.2% or 0.5% KNO3 for 48 to 72 h at alternating temperature of 25/35 °C. Both concentrations showed reasonable germination percentage greater than 85% at alternating temperature condition. Priming with KNO3 solution for 48 to 72 h improved not only germination percentage, but also uniformity. The increased duration of priming with KNO3 was positively correlated with an improved germination percentage. The effect of increasing concentration was the most apparent at a constant temperature (30 °C) regime with the treatment of 0.2% KNO3 priming. Germination percentage was increased from 34.3% to 68.0% 2 weeks after imbibition (WAI) as the priming duration was increased from 24 to 72 h. Priming with KNO3 for 3 days also had a modest effect on germination percentage (greater than 74.7%) at 1 WAI. Therefore, priming with 0.2% or 0.5% solution of KNO3 for 72 h is a recommended method that can be practically applied for increasing germination of paspalum under an alternating temperature (25/35 °C) condition. The regression analysis between odds of germination percentage and germination time showed that priming treatment increased internal activities during the second stage of seed germination.

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Maternal source affects seed germination of a rare Arabian desert species (Astragalus sieberi)

Botany ◽

10.1139/cjb-2020-0144 ◽

2021 ◽

Author(s):

Arvind Bhatt ◽

María Mercedes Carón ◽

Paulo Roberto de Moura Souza-Filho ◽

David Gallacher

Keyword(s):

Seed Germination ◽

Seedling Emergence ◽

Germination Percentage ◽

Population Variation ◽

Source Selection ◽

Seed Sources ◽

Native Seed ◽

Germination Characteristics ◽

Desert Areas

Understanding variation of seed germination in wild populations can assist restoration projects through improved seed source selection. Recruitment of artificially distributed seed can be improved by selecting for suitable dormancy and germination characteristics. We investigated seed germination and emergence responses of three Astragalus sieberi populations (Abdali, Liya and Salmi) to in situ storage for 5 months at depths of 0 and 5 cm, pre-sowing hydration for 12 and 24 hours, and chemical scarification with concentrated sulfuric acid for 5, 10 and 15 minutes. Germination percentage was low for freshly collected seeds (< 3%) from Abdali and Salmi. In situ storage partially enhanced germination. Pre-sowing hydration did not affect seedling emergence, but acid scarification effectively broke seed dormancy. The longest scarification treatment of 15 min produced the greatest seedling emergence, though populations responded differently. Results indicate that selection of maternal seed sources can improve revegetation projects of desert areas with native seed sources. Knowledge of inter-population variation can improve the understanding of the mechanisms regulating seed germination, thus optimizing restoration projects by selecting optimal seed sources.

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