Environmental effects on seed development and hardseededness in Stylosanthes hamata cv. Verano. II. Moisture supply and illuminance

1983 ◽  
Vol 34 (3) ◽  
pp. 271 ◽  
Author(s):  
PJ Argel ◽  
LR Humphreys
Keyword(s):  
Seed Production ◽  
Day Treatment ◽  
Seedling Emergence ◽  
Field Capacity ◽  
Seed Setting ◽  
Negative Effects ◽  
Seed Moisture Content ◽  
Seed Formation ◽  
Stylosanthes Hamata ◽  
Moisture Supply

The effects of variation in moisture supply and of level of illuminance during seed formation on the development of hardseededness and on the seed production of Stylosanthes hamata cv. Verano were studied in two glasshouse experiments. Verano plants were grown in pots containing 1.6 kg soil and were watered daily to field capacity until early flowering (43 days after seedling emergence). From day 43 to day 116, the plants were watered every 1, 2, 3 or 4 days. Leaf water potential immediately before rewatering varied from c. -20 to -28 bars in the 4-day treatment. Yields of seed pods were 5.8, 4.6, 3.8 and 3.8 g in the I-, 2-, 3- and 4-day treatments respectively. Severe water stress greatly reduced inflorescence density, had lesser negative effects on frequency of blooming, floret number, seed setting and proportion of florets forming a lower (beakless) articulation, and increased individual pod weight. Watering treatment had transitory and inconsistent effects on hardseededness. Seed production of Verano plants grown after flowering under shades with 30,40 or 59 % transmission or no shade was reduced by low level of illuminance, mainly because of effects on floret number per inflorescence; the proportion of florets forming a lower articulation and individual pod weight (but not seed setting) was also reduced by shading. The seed moisture content at different harvest occasions appeared to influence hardseededness, but shading had no consistent effect.

Environmental effects on seed development and hardseededness in Stylosanthes hamata cv. Verano. I. Temperature

1983 ◽  
Vol 34 (3) ◽  
pp. 261 ◽  
Author(s):  
PJ Argel ◽  
LR Humphreys
Keyword(s):  
Seed Development ◽  
Environmental Effects ◽  
Storage Conditions ◽  
Seed Setting ◽  
Negative Effects ◽  
Seed Formation ◽  
Moisture Contents ◽  
Stylosanthes Hamata ◽  
Seed Moisture ◽  
Embryo Dormancy

The level of hardseededness in Stylosanthes hamata cv. Verano grown in the open at St Lucia was positively and linearly related to temperature during seed formation; this relationship was stronger in 1976 than in 1977 when warmer conditions occurred. In two other experiments Verano plants were grown under the same conditions until early flowering and then exposed to differing temperature regimens. Seed production was maximal at 31/24�C (day/night), and cool temperatures (20/16�C or 18�C constant) had negative effects on inflorescence differentiation, rate of floret blooming and seed setting. Hardseededness developed most strongly at the high temperatures (35/28, 31/24�C, or 27 and 24�C constant), and this was also allied with lower seed moisture contents at harvest and in varying storage conditions. These findings may explain the variation in hardseededness of seed lots of differing provenance, which also may bear on the climatic adaptation of this short-lived plant. A range of mechanisms promote continued seed dormancy and its progressive release. Verano exhibited a transitory and weakly developed embryo dormancy at maturity, strong pod and testa inhibition of germination which decreased after 120 days of storage, and hardseededness continuing after 180 days of storage; the last was greater in the upper than in the lower articulation or seed pod.

Apex, lamina and shoot removal effects on seed production and growth of Stylosanthes hamata cv. Verano

1979 ◽  
Vol 30 (2) ◽  
pp. 293 ◽  
Author(s):  
B Wilaipon ◽  
SA Gigir ◽  
LR Humphreys
Keyword(s):  
Seed Yield ◽  
Yield Components ◽  
Floral Initiation ◽  
Seed Setting ◽  
Seed Formation ◽  
Stylosanthes Hamata ◽  
Seed Yield Components ◽  
Leaf Differentiation ◽  
Delayed Flowering ◽  
Bud Site

Swards of Stylosanthes hamata cv. Verano were simulated by growing plants in irrigated square pots placed edge to edge and discarding border rows. The effects on the events leading to seed formation of removing (1) all shoot apices, (2) apices plus 60% of laminae and (3) shoots supporting 60% of laminae were studied, when these treatments were applied at (1) a vegetative stage, (2) early floral initiation and (3) advanced floral initiation. Defoliation delayed flowering and reduced growth rates for 10–30 days subsequently, these effects increasing if bud sites were removed in addition to lamina and apices. In this heated glasshouse the final seed yield and most of the seed yield components were similar in all treatments, including undefoliated swards. Seed yield increased from 141 to 171 g m-2 when 60% of laminae only were removed at an early seed-setting stage in well-grown swards (LAI 6.9). In a subsequent experiment, removal of 33% of laminae at a similar advanced developmental stage increased seed yield from 106 to 180 g m-2, and other late defoliation treatments did not significantly influence seed yield. These effects are discussed in terms of altered patterns of apical dominance and leaf differentiation, bud site removal, assimilate supply to the inflorescences, and the consequences of delayed flowering.

Environmental effects on seed development and hardseededness in Stylosanthes hamata cv. Verano. III. Storage humidity and seed characteristics

1983 ◽  
Vol 34 (3) ◽  
pp. 279 ◽  
Author(s):  
PJ Argel ◽  
LR Humphreys
Keyword(s):  
Relative Humidity ◽  
Temperature Treatment ◽  
Seed Colour ◽  
Seed Moisture Content ◽  
Seed Formation ◽  
Stylosanthes Hamata ◽  
Seed Moisture ◽  
Palisade Cells ◽  
Seed Characteristics ◽  
Seed Provenance

Seed pods (upper articulation) from Stylosanthes hamata cv. Verano plants grown at 27,24 and 21�C from flowering onwards were suspended above saturated salt solutions which provided 77, 32, 15 or 6% relative humidity. The seed moisture content which developed after storage in 77 and 32% relative humidity was negatively related, and the degree of hardseededness positively related, to temperature of seed provenance. Seeds formed under high temperature had more lignin (which was concentrated in the counterpalisade cells) and hemicellulose, less cellulose, and shorter palisade cells than seeds formed under cooler temperature. Cutin content was independent of temperature, but the testa of hard seeds exhibited under the scanning electron microscope a more regular, evenly reticulate surface than that of soft seeds. Seed colour changed from dark to light as temperature of seed formation decreased from 27 to 21�C, but hardseededness within each temperature treatment was not consistently associated with seed colour.

Variability in habit, flowering and seed production within the Kangaroo Valley cultivar of Lolium perenne when grown in a range of environments

1990 ◽  
Vol 41 (5) ◽  
pp. 901 ◽  
Author(s):  
SG Shah ◽  
CJ Pearson ◽  
JW Read
Keyword(s):  
Seed Production ◽  
Seedling Emergence ◽  
Early Flowering ◽  
Population Characteristic ◽  
Seed Formation ◽  
Late Flowering ◽  
Seed Harvest ◽  
Different Populations ◽  
Seed Yields ◽  
Production Characteristics

Diversity of flowering and seed production characteristics were measured within and between seven populations of Kangaroo Valley perennial ryegrass. The hypothesis that these characteristics would not change when grown in diverse environments was tested. The average time from seedling emergence to spike emergence was similar for each of three biotypes that represented early, intermediate and late flowering populations. This occurred in spite of variation in this character of 54 to 72 days between plants within each of these biotypes. When data from all seven populations were combined, they formed a normal distribution with respect to time of flowering. Distinctive components of seed production were found for the different populations. Early flowering populations had higher seed yields and more but shorter spikes than late flowering populations. Wide variation in habit occurred within populations but there was a high correlation between erect habit and early flowering. Spikes of erect plants emerged 27 days earlier than prostrate plants. The seed formation characteristics of an early flowering population were unaltered when grown for three generations in diverse environments. The spike emergence and anthesis times for each of the seven populations were not changed when grown in new environments. We conclude that seed production of Kangaroo Valley ryegrass in environments similar to those described in these experiments will not significantly alter the population characteristic. For changes in the character of the population to occur, the new environment would have to be so severe to (a) restrict growth and select out a proportion of the progeny or (b) cause a change in the time of seed harvest.

Henbit (Lamium amplexicaule), Common Chickweed (Stellaria media), Shepherd's-Purse (Capsella bursa-pastoris), and Field Pennycress (Thlaspi arvense): Fecundity, Seed Dispersal, Dormancy, and Emergence

Weed Science ◽  
2014 ◽  
Vol 62 (1) ◽  
pp. 97-106 ◽  
Author(s):  
Erin C. Hill ◽  
Karen A. Renner ◽  
Christy L. Sprague
Keyword(s):  
Seed Production ◽  
Seedling Emergence ◽  
Crop Productivity ◽  
Seed Fate ◽  
Stellaria Media ◽  
Thlaspi Arvense ◽  
Emergence Patterns ◽  
Field Pennycress ◽  
Winter Annuals ◽  
Winter Annual

Winter annual weeds protect the soil from erosion and retain nutrients during the winter; however, they can also act as a host for crop pests and pathogens and impede planting. Increased knowledge of the reproductive biology and the seed fate of winter annuals would be useful to improve management and crop productivity. The objectives of this research were to determine the recruitment biology of shepherd's-purse, henbit, common chickweed, and field pennycress, including seed production, dispersal, dormancy, and seedling emergence, based on growing degree days (GDD). Henbit was the least prolific of the four weeds studied, producing 800 to 40,000 seeds m−2at naturally occurring densities; shepherd's-purse was the most prolific, producing 11,000 to 400,000 seeds m−2with 40 to 230 plants m−2. Fifty percent seed rain occurred for henbit, common chickweed, shepherd's-purse, and field pennycress at 620, 790, 880, and 1300 GDDBase,0C, respectively. Overall, seeds were dormant for all species at the time of dispersal. In 2 of 3 yr, dormancy of later-dispersed common chickweed decreased after 6 mo of storage at natural, fluctuating temperatures in the absence of water. The emergence patterns of the four species followed the Gompertz equation and were indicative of facultative winter annuals. The emergence patterns by rate were similar between henbit and common chickweed and between shepherd's-purse and field pennycress. Seed production, dispersal, dormancy, and seedling emergence were influenced by moisture; therefore, including a precipitation or soil moisture component into a GDD model (such as the use of hydrothermal time) would improve the accuracy of predicting winter annual reproduction, seed fate, and emergence.

scholarly journals Heliotropism and water availability effects on flowering dynamics and seed production in Macroptilium lathyroides

2006 ◽  
Vol 28 (2) ◽  
pp. 45-52 ◽  
Author(s):  
Armando Martins dos Santos ◽  
Luis Mauro Gonçalves Rosa ◽  
Lucia Brandão Franke ◽  
Carlos Nabinger
Keyword(s):  
Seed Production ◽  
Water Availability ◽  
Yield Components ◽  
Seed Weight ◽  
Field Capacity ◽  
Leaf Movements ◽  
Independent Effects ◽  
Total Seed ◽  
Macroptilium Lathyroides ◽  
Response To Water

The experiment was carried out in pots in a glasshouse, with one plant per pot and nine repetitions per treatment. The treatments consisted of free or restricted leaves, submited to 90-100% or 60-70% soil field capacity (FC). Only independent effects of water availability or leaf movement were observed on yield components. Plants under well-watered conditions and with freely orienting leaves were taller, and had a larger number of ramifications. The greater development favored the setting of a higher number of inflorescences per plant in these treatments. This behavior resulted in a high number of flowers, green and mature legumes per plant, thus resulting in high seed production which was the most evident response to water availability. Although individual seed weight was higher in the water stress treatment, total seed production was higher for well-watered plants, with no statistically significant effect of leaf movements.

Weed Seedling Emergence and Survival as Affected by Crop Canopy

2008 ◽  
Vol 22 (4) ◽  
pp. 736-740 ◽  
Author(s):  
Randy L. Anderson
Keyword(s):  
Winter Wheat ◽  
Seed Production ◽  
Spring Wheat ◽  
Seedling Emergence ◽  
Crop Canopy ◽  
Cool Season ◽  
Common Lambsquarters ◽  
Green Foxtail ◽  
Seedling Emergence And Survival ◽  
Weed Dynamics

This study measured impact of cool-season crops on seedling emergence, survival, and seed production of weeds common in corn and soybean. Weed dynamics were monitored in permanently marked quadrats in winter wheat, spring wheat, and canola. Three species, green foxtail, yellow foxtail, and common lambsquarters, comprised more than 80% of the weeds observed in the study. Seedling emergence was reduced by winter wheat, but not by spring wheat or canola, when compared with adjacent quadrats without a crop canopy. Approximately 10% of seedlings in spring wheat and canola developed into seed-bearing plants, but no seed-bearing plants were present in winter wheat at harvest. Common lambsquarters produced more than 1,100 seeds/plant, whereas a foxtail plant produced 85 seeds, averaged across spring wheat and canola. At harvest, new seedlings were present in all crops; thus, control after harvest will be required to prevent seed production in the fall. Winter wheat may provide an opportunity to disrupt population dynamics of weeds common in corn and soybean without requiring herbicides.

scholarly journals Potential Role of Sequential Glufosinate and Foramsulfuron Applications for Management of Fescues (Festucaspp.) in Wild Blueberry

2017 ◽  
Vol 31 (1) ◽  
pp. 100-110 ◽  
Author(s):  
Scott N. White ◽  
Shanthanu Krishna Kumar
Keyword(s):  
Field Study ◽  
Seed Production ◽  
Potential Role ◽  
Seedling Recruitment ◽  
Seedling Emergence ◽  
Seed Viability ◽  
Early Spring ◽  
Seedling Mortality ◽  
Wild Blueberry

Sheep and hair fescue are perennial, tuft forming grasses that spread by seed and form dense sods in wild blueberry fields. These sods compete with the crop for resources and hinder harvest. Field and greenhouse studies were conducted in 2015 to evaluate 1) the effect of sequential glufosinate and foramsulfuron applications on suppression of fescues in the greenhouse and field, and 2) efficacy of glufosinate and foramsulfuron on fescue seedlings when applied at 2, 4, 6, and 8 wk after seedling emergence in the greenhouse. Glufosinate applications at 750 and 1,005 g ai ha−1followed by foramsulfuron application at 35 g ai ha−1reduced fescue leaf number and biomass relative to foramsulfuron application alone in the greenhouse. In the field study, fescue flowering tuft density, tuft inflorescence height, seed production, and seed viability were reduced by foramsulfuron alone, but there was a trend towards lower seed production and tuft height when fescues were treated with glufosinate at 1,005 g ha−1followed by foramsulfuron. Foramsulfuron caused low seedling mortality at all application timings evaluated, but glufosinate caused >90% mortality in seedlings when applied at 2, 4, 6, or 8 wk after seedling emergence. Our results suggest that sequential applications of these herbicides are less effective under field conditions relative to results obtained in the greenhouse, though burndown glufosinate applications may have a role in reducing fescue seedling recruitment. Additional research should be conducted to determine the effect of early spring and autumn glufosinate applications on fescue seedling recruitment and suppression of established fescue tufts with subsequent foramsulfuron applications.

scholarly journals Conspecific and heterospecific grass litter effects on seedling emergence and growth in ragwort (Jacobaea vulgaris)

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246459
Author(s):  
Henrike Möhler ◽  
Tim Diekötter ◽  
Geeltje Marie Bauer ◽  
Tobias W. Donath
Keyword(s):  
Seedling Emergence ◽  
Management Tool ◽  
Litter Type ◽  
Negative Effects ◽  
Positive Effects ◽  
Mediated Effects ◽  
Jacobaea Vulgaris ◽  
Grass Litter ◽  
Early Seedling ◽  
Biomass Plant

Jacobaea vulgaris Gaertn. or common ragwort is a widespread noxious grassland weed that is subject to different regulation measures worldwide. Seedling emergence and growth are the most crucial stages for most plants during their life cycle. Therefore, heterospecific grass or conspecific ragwort litter as well as soil-mediated effects may be of relevance for ragwort control. Our study examines the effects of conspecific and heterospecific litter as well as ragwort conditioned soil on seedling emergence and growth. We conducted pot experiments to estimate the influence of soil conditioning (with, without ragwort), litter type (grass, ragwort, grass-ragwort-mix) and amount (200 g/m², 400 g/m²) on J. vulgaris recruitment. As response parameters, we assessed seedling number, biomass, height and number of seedling leaves. We found that 200 g/m² grass litter led to higher seedling numbers, while litter composed of J. vulgaris reduced seedling emergence. Litter amounts of 400 g/m² had negative effects on the number of seedlings regardless of the litter type. Results for biomass, plant height and leaf number showed opposing patterns to seedling numbers. Seedlings in pots treated with high litter amounts and seedlings in ragwort litter became heavier, grew higher and had more leaves. Significant effects of the soil conditioned by ragwort on seedling emergence and growth were negligible. The study confirms that the amount and composition of litter strongly affect seedling emergence and growth of J. vulgaris. Moreover, while conspecific litter and high litter amounts negatively affected early seedling development in ragwort, those seedlings that survived accumulated more biomass and got taller than seedlings grown in heterospecific or less dense litter. Therefore, ragwort litter has negative effects in ragwort germination, but positive effects in ragwort growth. Thus, leaving ragwort litter on pastures will not reduce ragwort establishment and growth and cannot be used as management tool.

Preharvest glyphosate in alfalfa for seed production: Effect on alfalfa seed yield and quality

2003 ◽  
Vol 83 (1) ◽  
pp. 189-197 ◽  
Author(s):  
W. E. May ◽  
H. A. Loeppky ◽  
D. C. Murrell ◽  
C. D. Myhre ◽  
J. J. Soroka
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Seed Quality ◽  
Seedling Emergence ◽  
Canada Thistle ◽  
Seedling Vigour ◽  
Yield And Quality ◽  
Alfalfa Seed ◽  
Medicago Sativa L ◽  
Seed Yields

Preharvest applications of glyphosate have been shown to be effective in controlling Canada thistle in annual crops, but may reduce alfalfa seed yield depending on time and rate of application. The objective of this study was to determine the effect of preharvest applications of glyphosate on subsequent alfalfa seed yield and quality. The effects of timing, 1, 26, 51 and 76% alfalfa seed pod maturity, and rate, 0, 440, 880, 1320, and 1760 g a.i. ha-1, of a preharvest application of glyphosate on alfalfa seed yield and quality in the year of application, and regrowth and seed yield in the following year were determined. The rate of glyphosate applied did not affect seed yield in the application year; however, in the following year, growth and seed yield were reduced as rates increased. Delaying the application of glyphosate increased seed yields in the application year, but decreased alfalfa regrowth and flowering the following year. Germination and seedling emergence were not affected by the rate or timing of the glyphosate. A preharvest application of glyphosate at 1760 g a.i. ha-1 at 76% pod maturity is a viable option in the last year of seed production. Key words: Alfalfa (Medicago sativa L.), glyphosate, abnormal seeds, seed quality, and seedling vigour

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