Seed Dormancy, Germination, and Seedling Recruitment in Weedy Setaria

2014 ◽  
pp. 33-102
Author(s):  
Jack Dekker
Keyword(s):  
Seed Dormancy ◽  
Seedling Recruitment

Secondary seed dormancy prolongs persistence of volunteer canola in western Canada

Weed Science ◽  
2003 ◽  
Vol 51 (6) ◽  
pp. 904-913 ◽  
Author(s):  
Robert H. Gulden ◽  
Steven J. Shirtliffe ◽  
A. Gordon Thomas
Keyword(s):  
Seed Dormancy ◽  
Seedling Recruitment ◽  
Seedling Emergence ◽  
Conventional Tillage ◽  
Western Canada ◽  
Tillage Systems ◽  
Spring Canola ◽  
Typical Summer ◽  
Different Soils

In western Canada, little is known about the seedbank ecology of volunteer canola. Therefore, integrated recommendations for the management of this weed are limited. In this study, we investigated the seedbank persistence and seedling recruitment of two spring canola genotype groups with different secondary seed dormancy potentials under contrasting tillage systems. The study was conducted at two locations with different soils in the Mixed Moist Grassland ecoregion of Saskatchewan. A single cohort seedbank was established in 1999 and was followed for 3 yr in successive wheat crops. In a separate laboratory study, the six canola genotypes examined were classified as those with high and those with medium potentials for the development of secondary seed dormancy (HD and MD, respectively). After one, two, and three winters, maximum persistence of 44, 1.4, and 0.2% of the original seedbank was observed among the treatments, respectively. In 2001, HD canola genotypes tended to exhibit 6- to 12-fold greater persistence than MD canola genotypes, indicating lower seedbank mortality in HD canola. Seedling recruitment of HD canola also was higher than MD canola when differences were observed between these genotype groups. Therefore, long-term seedbank persistence of canola can be reduced by growing genotypes with low inherent potential for the development of secondary seed dormancy. The proportion of persisting seeds tended to be higher under conventional tillage than under zero tillage because of lower seedbank mortality, but no clear distinction in seedbank persistence in terms of absolute time could be made between these two tillage systems. Volunteer canola seedling recruitment followed the pattern of a typical summer-annual weed, where seedling emergence was observed only during May and June.

Seed Dormancy and Seedling Recruitment in Smooth Barley (Hordeum murinum ssp. glaucum) Populations in Southern Australia

Weed Science ◽  
2012 ◽  
Vol 60 (3) ◽  
pp. 394-400 ◽  
Author(s):  
Benjamin Fleet ◽  
Gurjeet Gill
Keyword(s):  
Seed Dormancy ◽  
Seedling Recruitment ◽  
Seedling Emergence ◽  
South Australia ◽  
Conventional Tillage ◽  
The Other ◽  
Barley Plant ◽  
Weed Species ◽  
Time Interaction ◽  
Recruitment Behavior

Weedy barley species have emerged as important weeds in southern Australia, where they can be particularly difficult to control in cereal crops. Knowledge of seed dormancy mechanisms, germination ecology, and recruitment behavior in the field would facilitate development of effective weed-control programs for these weed species. Based on somatic chromosome number, smooth barley was identified as the species infesting all the sites sampled in South Australia. Smooth barley populations from cropping fields and noncrop habitats showed large differences in their pattern of dormancy loss. Noncrop populations (EP2, EP3, and MN2) rapidly lost dormancy during dry after-ripening and showed 70 to 95% germination at 3 mo after maturity. Five populations collected from cropping fields (EP1, EP4, EP5, MN1, and MN3), on the other hand, showed < 30% germination, even at 8 mo after maturity, when germination was assessed at 20/12 C day/night temperatures. These dormant, smooth barley populations from cropping fields were found to be highly responsive to cold stratification, with germination increasing in response to the duration of the treatment. Germination of dormant, smooth barley populations increased with the addition of gibberellic acid (0.001 M GA3), but only when lemma and palea had been removed. Recruitment behavior of smooth barley in the field was influenced by the population and the tillage system. A nondormant population, collected from a long-term pasture (MN2), showed high seedling emergence (> 90%) during autumn, which was well before planting of the winter crop (lentil). In contrast, the other three populations sampled from cropping fields showed very little seedling establishment (< 10%) before crop planting, which would make them difficult to control in cereals because there are no selective herbicides available for the control of weedy barley species. There was a significant seeding system by emergence time interaction (P < 0.001), which was reflected in greater in-crop, smooth barley plant densities under zero-till than under conventional tillage and no-till systems.

The benefits of seed banking for red maple (Acer rubrum): maximizing seedling recruitment

2005 ◽  
Vol 35 (4) ◽  
pp. 806-813 ◽  
Author(s):  
Janneke Hille Ris Lambers ◽  
James S Clark
Keyword(s):  
Life History ◽  
Seed Dormancy ◽  
Early Life ◽  
Seedling Recruitment ◽  
Seedling Survival ◽  
Acer Rubrum ◽  
Growing Season ◽  
Early Life History ◽  
Red Maple ◽  
Temperate Trees

Seed banking is assumed to be unimportant for temperate trees, because their seeds are short-lived in soils. However, even short-term seed banking could increase recruitment and affect population dynamics of seed-banking trees. To investigate this possibility, we examined early life-history stages of red maple (Acer rubrum L.), an abundant seed-banking tree in eastern forests. We found that seed banking benefits red maple by increasing germination when seedling survival is likely. Most red maple seeds germinate soon after spring dispersal, when seedling survival is high, or postpone germination to the following growing season, once seedling survival becomes less likely late in the summer. This occurs because seed dormancy increases during the growing season, matching a concurrent decrease in seedling survival. Our results and those of other studies suggest seed dormancy is increased by the same environmental factors (low light and low moisture) that also decrease seedling survival. We speculate that early life-history traits, including seed banking, may have contributed to this species' increased abundance in eastern deciduous forests in the last century.

Influence of Winter Seed Position and Recovery Date on Hairy Nightshade (Solanum sarrachoides) Recruitment and Seed Germination, Dormancy, and Mortality

Weed Science ◽  
2007 ◽  
Vol 55 (1) ◽  
pp. 49-59 ◽  
Author(s):  
R. Edward Peachey ◽  
Carol Mallory-Smith
Keyword(s):  
Seed Germination ◽  
Seed Dormancy ◽  
Weed Management ◽  
Seedling Recruitment ◽  
Germination Rate ◽  
Burial Depth ◽  
Undisturbed Soil ◽  
Linear Temperature ◽  
Hairy Nightshade ◽  
Seed Position

Understanding the factors regulating recruitment in diverse tillage systems will improve the efficacy of weed-management strategies. Experiments measured the effect of hairy nightshade winter seed position (burial depth) on seedling recruitment and seed germination, dormancy, and mortality. Hairy nightshade seeds were placed in soil tubes at 1 cm below the soil line and buried in the fall so that seeds were positioned in the soil at 1, 6, 13, and 25 cm below the soil surface. Tubes with undisturbed soil and seeds were removed from the field in March, April, and May of 2004 and 2005 and placed in wells in a heated, aluminum block with a linear temperature gradient from 22.7 to 36.0 C at 2.7 C intervals, and recruitment was measured. Seeds were also recovered from the soil tubes to determine effects of seed position on germination rate, mortality, and seed dormancy. Hairy nightshade seedling recruitment was greater for seeds positioned at 6, 13, and 25 cm during the winter than at 1 cm. Seed dormancy and mortality were greatest for seeds positioned at 1 cm, but that did not adequately account for the significant decrease in recruitment at 1 cm compared to seeds buried at 6, 13, or 25 cm. Protecting the seeds buried at 1 cm from rainfall during the winter increased seedling recruitment from 0 to 20% of buried seeds but had a negligible effect on seed mortality and dormancy. Soil density was negatively correlated with recruitment.

Breaking Seed Dormancy in Corchorus olitorius Landraces

Planta Medica ◽  
2008 ◽  
Vol 74 (03) ◽  
Author(s):  
AE-D Helaly ◽  
H Al-Amier ◽  
AA Al-Aziz ◽  
LE Craker
Keyword(s):  
Seed Dormancy ◽  
Corchorus Olitorius ◽  
Breaking Seed Dormancy

Plant mortality and seedling recruitment responses to flupropanate in grassland populations of Nassella trichotoma

2017 ◽  
Vol 70 ◽  
pp. 160-164 ◽  
Author(s):  
G.W. Bourdôt ◽  
S. Jackman ◽  
D.J. Saville
Keyword(s):  
New Zealand ◽  
Dose Response ◽  
Sodium Salt ◽  
Seedling Recruitment ◽  
Residual Activity ◽  
Application Rate ◽  
Plant Mortality ◽  
Complete Control ◽  
Bio Synthesis

Flupropanate (sodium 2,2,3,3 tetrafluoropropanate), a slow-acting lipid bio- synthesis-inhibiting herbicide, was recently registered in New Zealand as Taskforce (745 g/L flupropanate as the sodium salt) for the selective and long-term control of Nassella trichotoma (nassella tussock) in pastures. In five dose-response experiments in permanent hill pastures in Canterbury, conducted between 2012 and 2016, we measured the efficacy of the herbicide against established plants of N. trichotoma and its residual activity against recruiting seedlings. Mortality, as an average across the five sites, was 93% 1.5 years after applying 1.49 kg flupropanate/ha (the label-recommended rate), and 100% at 2.98 kg/ha. This indicates that an application rate higher than the label rate will be necessary for complete control of a N. trichotoma infestation. The presence of 1,000 and 6,250 visible seedlings of N. trichotoma/ha in the autumn 3.2 and 2.1 years after applying 1.49 kg flupropanate/ha (at a Greta Valley and Scargill site respectively) indicates that the herbicide’s soil residues had decayed within 12 months to a concentration lower than necessary to kill the germinating seedlings of N. trichotoma.

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