The seed ecology of Aegilops triuncialis: linking trait variation to growing conditions

2017 ◽  
Vol 27 (3) ◽  
pp. 183-198 ◽  
Author(s):  
Andrew R. Dyer
Keyword(s):  
Seed Mass ◽  
Seed Viability ◽  
Seed Type ◽  
Aegilops Triuncialis ◽  
Trait Variation ◽  
Growing Seasons ◽  
Small Seed ◽  
Annual Grasses ◽  
Growing Conditions ◽  
Plastic Responses

AbstractAdaptive plastic responses in invasive species allow for establishment and persistence despite the lack of genetic matching to new environments. The capacity of annual species to invade habitats to which they are not adapted is likely to be predicated on post-invasion seed trait variation correlated with conditions in the new habitat. To test this, I compared variation in seed traits and germination patterns of Aegilops triuncialis, an invasive annual grass, from 69 sample populations from 24 sites in California (USA) across 13 years. Seed mass, germination fractions, seed viability, and strength of induced dormancy between dimorphic seed pairs were used to investigate plastic variation within and among populations, across two general soil types, and among two widespread maternal genotypes. I found that seed mass variation was constrained although both seed types showed a 3-fold range among populations, 20–25% variation within populations between years, and was positively correlated with longer growing seasons. However, induced seed dormancy in the small seed type was correlated with large seed mass and to late-season precipitation, suggesting that longer growing seasons influence the strength of maternal and sibling chemical signals that induce dormancy in the small seeds. Thus variation in small seed germination fractions varies with the growing conditions experienced by the maternal plant. The greater longevity of the small seed type suggests that plasticity in germination in this species may contribute to seed bank formation, which is atypical of invasive annual grasses in California, and this may contribute to the persistence and spread of A. triuncialis in invaded ranges.

Seed production in cluster clover (Trifolium glomeratum L.). 2 Effect of sowing time and sowing rate on flowering time, abortion, seed size, and hardseededness

1998 ◽  
Vol 49 (6) ◽  
pp. 965 ◽  
Author(s):  
F. P. Smith ◽  
P. S. Cocks ◽  
M. A. Ewing
Keyword(s):  
Flowering Time ◽  
Seed Production ◽  
Seed Size ◽  
Western Australia ◽  
Seed Quality ◽  
Seed Mass ◽  
Above Ground Biomass ◽  
Sowing Time ◽  
Growing Seasons ◽  
Small Seed

An ecotype of cluster clover (Trifolium glomeratum L.) common to the wheatbelt of Western Australia was sown in pure undefoliated swards at rates in the range 2-256 kg/ha, on 2 dates to give growing seasons 13 and 18 weeks in length. Irrigation was phased out at the time of flowering of late-sown plots. The treatments generated a scale of seed production in cluster clover from 148 kg/ha (43 000 seeds/m2) to 1640 kg/ha (389 000 seeds/m2). Delayed sowing was more important in reducing seed production than was increasing sowing rate. By comparison with the early-sown plots, the late-sown plots had less above-ground biomass at flowering (2053 v. 2728 kg/ha); 48-66% fewer inflorescences per m2; a shorter vegetative phase (9 days); fewer seeds per inflorescence (26 v. 31); and lesser seed mass (337 µg v. 436 µg). There was little effect of the treatments on hardseededness except that hardseededness after 1 season in the field was higher in seeds from late-sown swards at high sowing rate (58%) than from late-sown swards at low sowing rate or early-sown swards (40%). Neither sowing rate nor sowing time influenced the within season pattern of hardseed breakdown. The results indicate that cluster clover is capable of massive seed production, and that even under highly stressed conditions seed production is maximised by a high reproductive allocation and small seed size. Despite conditions which reduced seed production by up to 90%, cluster clover is able to maintain its seed quality. Relatively few inviable seeds are produced and hardseededness is either unaffected or enhanced.

Seed size as a determinant of germination rate in Crepis tectorum (Asteraceae): evidence from a seed burial experiment

1996 ◽  
Vol 74 (4) ◽  
pp. 568-572 ◽  
Author(s):  
Stefan Andersson
Keyword(s):  
Seed Size ◽  
Germination Rate ◽  
Local Population ◽  
Seed Viability ◽  
Seed Burial ◽  
Small Seed ◽  
Crepis Tectorum ◽  
Winter Annual ◽  
Selection For ◽  
The Relationship

The present study of the winter annual Crepis tectorum examines the relationship between seed (achene) size and the extent to which seeds resist germination during the year of their production. I carried out two seed burial experiments, one at an outcrop site occupied by a small-seeded population, and another in an experimental garden with soil from the same field site, with seeds representing the local population and a segregating generation of a cross between two other populations. Using logistic regression with data corrected for seed viability, I found an association between small seed size and failure to germinate in the first autumn. The small seed size characterizing many outcrop populations may have evolved as a response to selection for delaying germination in a habitat subject to unpredictable droughts during the growth season. Keywords: Crepis tectorum, germination, seed bank, seed size.

Seed mass and early survivorship of tree species in upland clearings and shelterwoods

1998 ◽  
Vol 28 (9) ◽  
pp. 1307-1316 ◽  
Author(s):  
D F Greene ◽  
E A Johnson
Keyword(s):  
Leaf Litter ◽  
Power Law ◽  
Tree Species ◽  
Picea Glauca ◽  
Mineral Soil ◽  
Seed Mass ◽  
High Survivorship ◽  
Small Seed ◽  
Negative Exponential ◽  
The Relationship

We examined recommended sowing densities of 25 North American tree species (26 observations) to measure the relationship between juvenile survivorship and seed mass in large clearings and shelterwoods. Two models for expressing the relationship (simple power law or a cumulative negative exponential adjusted to account for rodent-repellent application and seedbed type) all showed that survivorship is highly dependent on seed mass. For a small seed, mineral soil and thin humus confer roughly equally high survivorship. Leaf litter is very poor, and undisturbed thick moss appears to be the worst possible organic seedbed on upland sites. An examination of 30 records of Picea glauca (Moench) Voss survivorship (3- to 6-year-old cohorts) on mineral soil revealed substantial intraspecific variation with only 50% of the values within twofold of the predicted value.

Control of Downy Brome (Bromus tectorum) with Herbicides and Perennial Grass Competition

1998 ◽  
Vol 12 (2) ◽  
pp. 391-396 ◽  
Author(s):  
Tom D. Whitson ◽  
David W. Koch
Keyword(s):  
Dry Matter ◽  
Perennial Grass ◽  
Integrated Approach ◽  
Growth Stages ◽  
Downy Brome ◽  
Cool Season ◽  
Growing Seasons ◽  
Annual Grasses ◽  
Russian Wildrye

Long-term control of downy brome with an integrated approach is needed in order to sustain range productivity. Studies were conducted to study the effectiveness of a combination of downy brome control practices. In two studies, glyphosate and paraquat were evaluated at various rates for up to three successive years for control of downy brome in rangeland. A third study evaluated the competitiveness of perennial cool-season grasses against downy brome in the absence of herbicides. Glyphosate, at 0.55 kg/ha, and 0.6 kg/ha paraquat provided selective downy brome control on rangeland when applications were combined with intensive grazing. Downy brome control was greater than 90% following two sequential years of 0.6 kg/ha paraquat at either the two- to eight-leaf stage or bloom stage at both study locations. At one study location, 0.55 kg/ha glyphosate provided 97% control after the first application at both growth stages. In the second study, control averaged greater than 92% following three sequential applications of glyphosate. When perennial cool-season grasses were seeded in the spring following fall tillage (no herbicides) and allowed to establish for three growing seasons, three of the five species were effective in reducing the reestablishment of downy brome. ‘Luna’ pubescent wheatgrass, ‘Hycrest’ crested wheatgrass, ‘Sodar’ streambank wheatgrass, ‘Bozoisky’ Russian wildrye, and ‘Critana’ thickspike wheatgrass controlled 100, 91, 85, 45, and 32% of the downy brome, respectively. Yields of perennial grass dry matter were 1,714, 1,596, 1,135, 900, and 792 kg/ha. Replacing noncompetitive annual grasses with competitive cool-season perennials will provide a longer term solution to a downy brome problem than the use of herbicides alone or with intensive grazing.

scholarly journals Impact of Row Spacing, Sowing Density and Nitrogen Fertilization on Yield and Quality Traits of chia (Salvia Hispanica L.) Cultivated in southwestern Germany

Agronomy ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 136 ◽  
Author(s):  
Samantha Grimes ◽  
Timothy Phillips ◽  
Filippo Capezzone ◽  
Simone Graeff-Hönninger
Keyword(s):  
Field Experiments ◽  
Seed Mass ◽  
N Fertilization ◽  
Row Spacing ◽  
Quality Traits ◽  
Yield And Quality ◽  
Chia Seed ◽  
Salvia Hispanica L ◽  
Growing Conditions ◽  
Seed Yields

To obtain high chia seed yields and seed qualities, a suitable crop management system needs to be developed for the given growing conditions in southwestern Germany. Field experiments were conducted at the experimental station Ihinger Hof in two consecutive years (2016, 2017). The study aimed to evaluate yield and quality traits of chia depending on different (i) row spacing (35, 50 and 75 cm), (ii) sowing densities (1, 1.5 and 2 kg ha−1) and, (iii) N-fertilization rates (0, 20 and 40 kg N ha−1). It consisted of three independent, completely randomized field experiments with three replications. Results showed that chia seed yields ranged from 618.39 to 1171.33 kg ha−1 and that a thousand seed mass of 1.14 to 1.24 g could be obtained. Crude protein-, crude oil- and mucilage contents varied from 18.11–23.91%, 32.16–33.78% and 10.00–13.74%, respectively. Results indicated that the year of cultivation and the accompanied environmental conditions, like precipitation or temperature, influenced the determined traits more than the applied agronomic practices. As average seed yields exceeded those obtained in the countries of origin (Mexico, Guatemala) while having comparable quality characteristics, chia holds great potential as an alternative crop for farmers in southwestern Germany.

scholarly journals The early growth of supermassive black holes in cosmological hydrodynamic simulations with constrained Gaussian realizations

2020 ◽  
Vol 496 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Kuan-Wei Huang ◽  
Yueying Ni ◽  
Yu Feng ◽  
Tiziana Di Matteo
Keyword(s):  
Black Holes ◽  
Large Scale ◽  
Initial Conditions ◽  
Seed Mass ◽  
Early Growth ◽  
Supermassive Black Holes ◽  
Formation Mechanisms ◽  
Density Peak ◽  
Hydrodynamic Simulations ◽  
Small Seed

ABSTRACT The paper examines the early growth of supermassive black holes (SMBHs) in cosmological hydrodynamic simulations with different BH seeding scenarios. Employing the constrained Gaussian realization, we reconstruct the initial conditions in the large-volume bluetides simulation and run them to z = 6 to cross-validate that the method reproduces the first quasars and their environments. Our constrained simulations in a volume of $(15 \, h^{-1} {\rm Mpc})^3$ successfully recover the evolution of large-scale structure and the stellar and BH masses in the vicinity of a ${\sim}10^{12} \, M_{\odot }$ halo which we identified in bluetides at z ∼ 7 hosting a ${\sim}10^9 \, M_{\odot }$ SMBH. Among our constrained simulations, only the ones with a low-tidal field and high-density peak in the initial conditions induce the fastest BH growth required to explain the z > 6 quasars. We run two sets of simulations with different BH seed masses of 5 × 103, 5 × 104, and $5 \times 10^5 \, h^{-1} M_{\odot }$, (i) with the same ratio of halo to BH seed mass and (ii) with the same halo threshold mass. At z = 6, all the SMBHs converge in mass to ${\sim}10^9 \, M_{\odot }$ except for the one with the smallest seed in (ii) undergoing critical BH growth and reaching 108 – $10^9 \, M_{\odot }$, albeit with most of the growth in (ii) delayed compared to set (i). The finding of eight BH mergers in the small-seed scenario (four with masses 104 – $10^6 \, M_{\odot }$ at z > 12), six in the intermediate-seed scenario, and zero in the large-seed scenario suggests that the vast BHs in the small-seed scenario merge frequently during the early phases of the growth of SMBHs. The increased BH merger rate for the low-mass BH seed and halo threshold scenario provides an exciting prospect for discriminating BH formation mechanisms with the advent of multimessenger astrophysics and next-generation gravitational wave facilities.

The effect of growing sites on grain quality of oats and pasting properties of oatmeals

1999 ◽  
Vol 50 (8) ◽  
pp. 1409 ◽  
Author(s):  
M. X. Zhou ◽  
M. Glennie-Holmes ◽  
G. L. Roberts ◽  
K. Robards ◽  
S. Helliwell
Keyword(s):  
Chemical Composition ◽  
Pasting Properties ◽  
Kernel Weight ◽  
Milling Quality ◽  
Growing Seasons ◽  
South Wales ◽  
Grain Milling ◽  
Oil Concentration ◽  
Growing Conditions

To assess the effect of growing sites on oat quality, 8 varieties were grown at 13 sites in New South Wales, Australia, in the 1995–96 and 1996–97 growing seasons. Grain milling quality, chemical composition, and pasting properties differed significantly between sites and were related to both variety and growing conditions. Varieties were the main determining factor of kernel size, kernel weight, and oil concentration, whereas growing conditions accounted for most of the variance in groat percentage and protein concentration. Breeding and selection offer opportunities for improving oat quality, and selecting suitable sites to grow oats could greatly improve milling quality and pasting properties, and ensure appropriate chemical composition.

Genetic diversity assessment of extra-early maturing yellow maize inbreds and hybrid performance inStriga-infested andStriga-free environments

2012 ◽  
Vol 151 (4) ◽  
pp. 519-537 ◽  
Author(s):  
I. C. AKAOGU ◽  
B. BADU-APRAKU ◽  
V. O. ADETIMIRIN ◽  
I. VROH-BI ◽  
M. OYEKUNLE ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Grain Yield ◽  
Central Africa ◽  
Striga Hermonthica ◽  
Environment Interaction ◽  
Maize Production ◽  
Growing Seasons ◽  
Diversity Assessment ◽  
Early Maturing ◽  
Growing Conditions

SUMMARYMaize (Zea maysL.), a major staple food crop in West and Central Africa (WCA), is adapted to all agro-ecologies in the sub-region. Its production in the sub-region is greatly constrained by infestation ofStriga hermonthica(Del.) Benth. The performance and stability of the extra-early maturing hybrids, which are particularly adapted to areas with short growing seasons, were assessed underStriga-infested andStriga-free conditions. A total of 120 extra-early hybrids and an open-pollinated variety (OPV) 2008 Syn EE-Y DT STR used as a control were evaluated at two locations each underStriga-infested (Mokwa and Abuja) andStriga-free (Ikenne and Mokwa) conditions in 2010/11. TheStriga-resistant hybrids were characterized by higher grain yield, shorter anthesis–silking interval (ASI), better ear aspect, higher numbers of ears per plant (EPP), lowerStrigadamage rating, and lower number of emergedStrigaplants at 8 and 10 weeks after planting (WAP) compared with the susceptible inbreds. UnderStrigainfestation, mean grain yield ranged from 0·71 to 3·18 t/ha and 1·19 to 3·94 t/ha underStriga-free conditions. The highest yielding hybrid, TZEEI 83×TZEEI 79, out-yielded the OPV control by 157% underStrigainfestation. The hybrids TZEEI 83×TZEEI 79 and TZEEI 67×TZEEI 63 were the highest yielding under bothStriga-infested andStriga-free conditions. The genotype main effect plus genotype×environment interaction (GGE) biplot analysis identified TZEEI 88×TZEEI 79 and TZEEI 81×TZEEI 95 as the ideal hybrids across research environments. Twenty-three pairs of simple sequence repeat (SSR) markers were used to assess the genetic diversity among the inbred lines. The correlations between the SSR-based genetic distance (GD) estimates of parental lines and the means observed in F1hybrid underStrigainfestation and optimum growing conditions were not significant for grain yield and other traits except ASI under optimum conditions. Grain yield of inbreds was not significantly correlated with that of F1hybrids. However, a significant correlation existed between F1hybrid grain yield and heterosis underStrigainfestation (r=0·72,P<0·01). These hybrids have the potential for increasing maize production inStrigaendemic areas in WCA.

scholarly journals Winter Oilseed Rape (Brassica napus L.) Yield Components in Agro–ecological Conditions of Banja Luka Region

2018 ◽  
Vol 18 (3) ◽  
pp. 175
Author(s):  
Danijela Kondić ◽  
Đurađ Hajder ◽  
Saša Marinković ◽  
Miloš Nožinić
Keyword(s):  
Oilseed Rape ◽  
Yield Components ◽  
Seed Weight ◽  
Seed Mass ◽  
Index Number ◽  
Total Production ◽  
Important Species ◽  
Ecological Conditions ◽  
Growing Seasons ◽  
Banja Luka

Due to its numerous agricultural and industrial purposes, oilseed rape is a very important species. The total production of oilseed rape in the Republic of Srpska is faced with noticeable variation throughout years, with an increase in last three years. The oilseed rape yield is strongly influenced by environmental factors. The objective of this study was to analyze yield components of oilseed rape in agro–ecological conditions of Banja Luka. Four oilseed rape hybrids were used: PR46W21, PR46W20, PR46W14 and PR45DO3 in two growing seasons: 2012/13 and 2013/14. Yield components tested were: pod mass (g), seed mass per pod (g), pod index (%), number of seeds per pod and 1000–seed weight (g). Factorial 2×4 ANOVA and Fisher's LSD test were used to analyze data, with growing seasons (years) and hybrids as factors. Growing season significantly affected the pod mass (g), total seed mass per pod (g) and 1000–seed weight. Generally, higher yield component values were obtained in the second examined year (2013/14).

scholarly journals Using Quinclorac to Control Annual Grasses and Palmer Amaranth in Grain Sorghum (Sorghum bicolor L.)

2021 ◽  
Vol 12 ◽  
pp. 1-10
Author(s):  
James Grichar ◽  
Travis Janak
Keyword(s):  
Field Studies ◽  
Grain Sorghum ◽  
Palmer Amaranth ◽  
Application Timing ◽  
Growing Seasons ◽  
South Central ◽  
Untreated Check ◽  
Central Texas ◽  
Annual Grasses ◽  
Sorghum Bicolor L

Field studies were conducted during the 2015 and 2016 growing seasons in south-central Texas to determine control of Palmer amaranth and annual grasses along with grain sorghum tolerance to quinclorac alone and in various combinations when applied to weeds < 5 cm (EPOST) or 10 to 16 cm tall (LPOST). When evaluated late-season quinclorac alone at 0.43 kg ae ha-1 controlled broadleaf signalgrass 72% when applied EPOST and 91% when applied LPOST. Combinations of quinclorac with either atrazine, pyrasulfotole + bromoxynil, dicamba, or dimethenamid-P controlled Palmer amaranth 88 to 100% when applied EPOST or LPOST; however, broadleaf signalgrass control with these combination was better when applied LPOST (75 to 95%) compared with EPOST (37 to 72%) applications. Texas millet control with quinclorac was poor in both years and was never greater than 54%. Quinclorac plus either atrazine, pyrasulfotole + bromoxynil, dicamba, or atrazine + dimethenamid-P caused at least 20% sorghum injury at one of three locations. No yield reductions from the untreated check were noted in either year; however, in 2016 all treatments with the exception of quinclorac alone at 0.29 kg ha-1 applied EPOST, quinclorac + pyrasulfotole + bromoxynil applied LPOST, quinclorac + atrazine + pyrasulfotole + bromoxynil applied LPOST, and quinclorac + dicamba at either application timing produced yields that were greater than the untreated check.

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