Variation of Seed Dormancy and Germination Ecology of Cowcockle (Vaccaria hispanica)

Weed Science ◽  
2014 ◽  
Vol 62 (3) ◽  
pp. 483-492 ◽  
Author(s):  
Hema S. N. Duddu ◽  
Steven J. Shirtliffe
Keyword(s):  
Seed Dormancy ◽  
Great Plains ◽  
Northern Great Plains ◽  
Light Conditions ◽  
Primary Dormancy ◽  
Local Environments ◽  
Temperature Regimes ◽  
Effects Of Temperature ◽  
Two Temperature ◽  
Seed Dormancy And Germination

Cowcockle, an introduced summer annual weed of the Northern Great Plains, is being considered for domestication because of its high quality starch, cyclopeptides, and saponins. Loss of seed dormancy is one of the key desirable traits for domestication. To determine the potential for domestication of this species, an understanding of the seed dormancy and germination patterns is required. The objectives of this study were to evaluate seed dormancy in cowcockle ecotypes and determine how temperature and light affect seed dormancy. We evaluated 15 populations of cowcockle for primary dormancy by exposing them to five temperatures (5, 7.5, 10, 15, and 20 C) under two temperature regimes (constant and alternating) in both dark and light conditions. Freshly matured seeds of all the populations showed high levels of primary dormancy except ‘Mongolia’. Lower levels of dormancy at medium temperatures (10 and 15 C) and greater dormancy at low and high temperatures suggest conditional dormancy, a state at which seeds germinate over a narrower range of conditions compared to nondormant seeds. The effects of temperature regime, light, and their interaction was significant only at suboptimal (5 and 7.5 C) and supraoptimal (20 C) temperatures. Under these conditions, alternating temperatures were more effective in breaking the conditional dormancy, followed by light. The variation in optimum temperature, light, and their interactions among the cowcockle populations may be due to the plants evolving to adapt to their local environments. From a domestication perspective, the conditional dormancy in cowcockle can be observed as an evolutionary mechanism that prevents untimely germination following maturity and may not be a major obstacle for its domestication.

Inter- and intra-varietal variation in aerobic methane emissions from environmentally stressed pea plants

Botany ◽  
2018 ◽  
Vol 96 (12) ◽  
pp. 837-850 ◽  
Author(s):  
Awatif M. Abdulmajeed ◽  
Mohammad I. Abo Gamar ◽  
Mirwais M. Qaderi
Keyword(s):  
Stress Factors ◽  
Interactive Effects ◽  
Controlled Environment ◽  
Uvb Radiation ◽  
Pisum Sativum L ◽  
Temperature Regimes ◽  
Varietal Variation ◽  
Growth Chambers ◽  
Effects Of Temperature ◽  
Two Temperature

Environmental stress factors can influence methane (CH4) emissions from plants. There are a few studies on the interactive effects of stress factors on plant aerobic CH4, but none on the comparative evaluation of CH4 emissions between and among plant varieties. We examined the effects of temperature, UVB radiation, and watering regime on CH4 emissions from 10 pea (Pisum sativum L.) varieties first and then selected two varieties with the highest (237J Sundance; var. 1) and lowest (422 Ho Lan Dow; var. 2) emissions for further studies. Plants were grown in controlled-environment growth chambers under two temperature regimes (22 °C / 18 °C and 28 °C / 24 °C, 16 h light / 8 h dark), two UVB levels (0 and 5 kJ·m−2·d−1), and two watering regimes (well-watered and water-stressed) for 14 days, after one week of growth under 22 °C / 18 °C. Higher temperatures and water stress increased CH4 emissions, and increased emission was associated with stress. Pea varieties varied in growth and CH4 emissions; var. 1 was more stressed and had higher emission than var. 2. In the stressed variety, the water-stressed plants grown under higher temperatures at UVB5 had the highest CH4 emission, whereas the well-watered plants grown under lower temperatures at UVB5 had the lowest emission. We conclude that climatic stress conditions increase CH4 emissions, which vary with plant varieties.

Factors controlling seed dormancy and germination response of Brachypodium hybridum growing in the hot arid mountains of the Arabian Desert

Botany ◽  
2019 ◽  
Vol 97 (7) ◽  
pp. 371-379 ◽  
Author(s):  
Masarra Elgabra ◽  
Ali El-Keblawy ◽  
Kareem A. Mosa ◽  
Sameh Soliman
Keyword(s):  
Seed Dormancy ◽  
Light Quality ◽  
Genetic Model ◽  
Germination Rate ◽  
Red Light ◽  
Germination Percentage ◽  
Light Conditions ◽  
One Year ◽  
Native And Introduced Ranges ◽  
Seed Dormancy And Germination

Seed dormancy and germination have been studied in the genetic model Brachypodium species complex in cooler, moist higher latitudes. Studying environmental factors in arid mountains affecting dormancy and germination in Brachypodium complex could determine the factors controlling these processes. This study assesses the impacts of temperature during seed maturation, seed after-ripening, drought, photoperiod, and thermoperiod on final germination and germination rate index of B. hybridum in the Arabian Desert. Seeds were germinated under dark or light conditions and under different ratios of red:far-red light, with three diurnal thermoperiods. The final germination percentage was significantly greater at 15/25 °C and 20/30 °C than at 25/35 °C and in light rather than in darkness. Seeds that reached maturity at 15/25 °C attained greater germination rates and faster germination than those that reached maturity at 20/30 °C. One-year after-ripening enhanced the final germination percentage and reduced photoperiod requirements. Light quality did not affect final germination percentage. The seeds tolerated drought of up to –0.8 MPa polyethylene glycol. The tolerance of B. hybridum seeds produced at higher thermoperiods to moderate levels of osmotic stress and their higher dormancy indicate that this species has the potential to survive the projected global warming in its native and introduced ranges.

scholarly journals Effects of light and temperature on lettuce seedlings.

1973 ◽  
Vol 21 (2) ◽  
pp. 102-109 ◽  
Author(s):  
K. Verkerk ◽  
C.J.T. Spitters
Keyword(s):  
High Temperature ◽  
Light Intensity ◽  
Leaf Area ◽  
Temperature Regime ◽  
Natural Light ◽  
Light Conditions ◽  
Subsequent Growth ◽  
High Temperature Regime ◽  
Temperature Regimes ◽  
Effects Of Temperature

In the first of 2 experiments lettuces were grown either under natural light conditions in the glasshouse in December and January or under 8- or 16-h daylengths, with several temperature regimes, and the leaf area per plant was measured after 22 and 45 days. Under natural light growth during the first 22 days was slight but subsequent growth was greatest with a light/dark temperature regime of 13/13 deg C, followed by one of 17/17 deg . With an 8-h day growth with diurnally changing temperatures was much greater than with constant ones, the best results being obtained with a regime of 25/17 deg . With a 16-h day the effect of diurnal temperature was much less marked and a constant high temperature regime of 21/21 deg gave better results than one of 25/17 deg . In the second experiment the plants were grown for 4 weeks under the same temperature regimes with 8- or 16-h daylengths, but the light intensity was varied by placing the plants at 2 vertical distances from the overhead lamps and all plants receiving a 16-h daylength were shaded by cheesecloth. The best results were obtained with a 16-h daylength with the plants placed close to the lamps; the effects of temperature were not so marked, but regimes of 25/17, 21/13 or 17/17 deg were the most satisfactory. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Regulation of seed dormancy and germination by nitrate

2018 ◽  
Vol 28 (3) ◽  
pp. 150-157 ◽  
Author(s):  
Lisza Duermeyer ◽  
Ehsan Khodapanahi ◽  
Dawei Yan ◽  
Anne Krapp ◽  
Steven J. Rothstein ◽  
...  
Keyword(s):  
Seed Germination ◽  
Seed Dormancy ◽  
Wild Type ◽  
Gene Encoding ◽  
Environmental Signals ◽  
Primary Dormancy ◽  
Low Concentrations ◽  
Catabolic Enzyme ◽  
Seed Dormancy And Germination ◽  
Nitrate Signalling

AbstractNitrate promotes seed germination at low concentrations in many plant species, and functions as both a nutrient and a signal. As a nutrient, it is assimilated via nitrite to ammonium, which is then incorporated into amino acids. Nitrate reductase (NR) catalyses the reduction of nitrate to nitrite, the committed step in the assimilation. Seed sensitivity to nitrate is affected by other environmental factors, such as light and after-ripening, and by genotypes. Mode of nitrate action in seed germination has been well documented in Arabidopsis thaliana and the hedge mustard Sisymbrium officinale. In these species nitrate promotes seed germination independent of its assimilation by NR, suggesting that it acts as a signal to stimulate germination. In Arabidopsis, maternally applied nitrate affects the degree of primary dormancy in both wild-type and mutants defective in NR. This indicates that nitrate acts not only during germination, but also during seed development to negatively regulate primary dormancy. Functional genomics studies in Arabidopsis have revealed that nitrate elicits downstream events similar to other germination stimulators, such as after-ripening, light and stratification, suggesting that these distinct environmental signals share the same target(s). In Arabidopsis, the NIN-like protein 8 (NLP8) transcription factor, which acts downstream of nitrate signalling, induces nitrate-dependent gene expression. In particular, a gene encoding the abscisic acid (ABA) catabolic enzyme CYP707A2 is directly regulated by NLP8. This regulation triggers a nitrate-induced ABA decrease that permits seed germination. This review article summarizes an update of our current understanding of the regulation of seed dormancy and germination by nitrate.

Effects of Temperature on Damage to Velvetleaf (Abutilon theophrasti) by the Scentless Plant Bug Niesthrea louisianica

Weed Science ◽  
1987 ◽  
Vol 35 (3) ◽  
pp. 324-327 ◽  
Author(s):  
David T. Patterson ◽  
Robert D. Coffin ◽  
Neal R. Spencer
Keyword(s):  
Seed Production ◽  
Natural Populations ◽  
Growing Season ◽  
Abutilon Theophrasti ◽  
Controlled Environment ◽  
Temperature Regimes ◽  
Effects Of Temperature ◽  
Delayed Flowering ◽  
Two Temperature ◽  
Increase Population Density

In controlled-environment chambers, the scentless plant bug Niesthrea louisianica Sailer damaged reproductive structures of velvetleaf (Abutilon theophrasti Medik. # ABUTH) and reduced viable seed production by 98 to 99%, in comparison with insect-free control plants. The insect completed its life cycle on velvetleaf in two temperature regimes simulating warm growing-season conditions in Mississippi (29/23 C day/night) and Minnesota (24/18 C). Feeding by N. louisianica delayed flowering, capsule development, and capsule and seed maturation in biotypes of velvetleaf from Mississippi and Minnesota, in both temperature regimes. Numbers and weights of capsules and seed were lower in the infested plants. Augmentation of natural populations of N. louisianica to increase population density early in the growing season might be effective in reducing velvetleaf seed production.

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