Seed germination response of a potential rangeland weed Psilocaulon granulicaule to selected environmental conditions

2020 ◽  
Vol 68 (5) ◽  
pp. 363
Author(s):  
Rekha Ranaweera ◽  
Sandra L. Weller ◽  
Singarayer K. Florentine
Keyword(s):  
Water Stress ◽  
Heat Shock ◽  
Seed Germination ◽  
Management Practices ◽  
Germination Rate ◽  
Radiant Heat ◽  
Weed Species ◽  
Light Regimes ◽  
Heat Shocks ◽  
Environmental Weed

Studies show that just over 620 non-native naturalised plant species have been recorded within the Australian rangelands, some of which have a capacity to cause significant impacts on rangeland flora and grazing activity. Although Psilocaulon granulicaule (Haw.), Schwantes is listed as a highly invasive environmental weed species, there has been no previous research into its seed ecology. Therefore, this study was conducted to investigate the effects of temperature, light, pH, water stress, heat-shock, and salinity on the germination of P. granulicaule. In this study, four temperature regimes covering four different day and night temperature variations (17–7°C, 25–15°C, 30–25°C and 40–30°C) and two light regimes (12-h light–12-h dark, 24-h dark) were investigated. The effects of pH, water stress, heat-shock and salinity were investigated, using pH buffers, polyethylene glycol solutions, three heat shock events under four temperatures and a range of NaCl solutions. These tests were conducted under the identified optimum temperature range (25/15°C) and light regime for seed germination. The results showed that both temperature and photoperiod significantly influenced the germination rate, with 94.2% germination in the 25–15°C range under a 12-h light-12-h dark regime. Higher temperatures (30–40°C) reduced seed germination to <58% germination in both light regimes (57.5%, 12-h light-12-h dark; 54.17%, 24-h dark). The highest germination rates were observed in low pH solutions, high moisture levels, low heat-shocks and low salinity. The study showed that this species is sensitive to environmental factors such as temperature, light, pH, moisture, heat shock and salinity, suggesting that these factors can be used as critical indicators to guide effective management practices to address this weed problem. Given that seeds are sensitive to radiant heat, burning could be used as a tool to effectively manage this species.

scholarly journals Factors affecting Cyperus difformis seed germination and seedling emergence

2013 ◽  
Vol 31 (4) ◽  
pp. 823-832 ◽  
Author(s):  
A. Derakhshan ◽  
J. Gherekhloo
Keyword(s):  
Seed Germination ◽  
Integrated Management ◽  
Germination Rate ◽  
Seedling Emergence ◽  
Management Strategies ◽  
Soil Surface ◽  
Weed Species ◽  
Factors Affecting ◽  
Cyperus Difformis ◽  
Emergence Patterns

Specific knowledge about the dormancy, germination, and emergence patterns of weed species aids the development of integrated management strategies. Laboratory studies were conducted to determine the effect of several environmental factors on seed germination and seedling emergence of Cyperus difformis. Germination of freshly harvested seeds was inhibited by darkness; however, when seeds were subsequently transferred to complete light they germinated readily. Our results showed that 2 wk of cold stratification overcome the light requirement for germination. Seeds of C. difformis were able to germinate over a broad range of temperatures (25/15, 30/20, 35/25, and 40/30 ºC day/night). The response of germination rate to temperature was described as a non-linear function. Based on model outputs, the base, the optimum and the ceiling temperatures were estimated as 14.81, 37.72 and 45 ºC, respectively. A temperature of 120 ºC for a 5 min was required to inhibit 50% of maximum germination. The osmotic potential and salinity required for 50% inhibition of maximum germination were -0.47 MPa and 135.57 mM, respectively. High percentage of seed germination (89%) was observed at pH=6 and decreased to 12% at alkaline medium (pH 9) pH. Seeds sown on the soil surface gave the greatest percentage of seedling emergence, and no seedlings emerged from seeds buried in soil at depths of 1 cm.

Germination and Emergence of Virginia Buttonweed (Diodia virginiana)

Weed Science ◽  
1991 ◽  
Vol 39 (1) ◽  
pp. 37-41 ◽  
Author(s):  
James H. Baird ◽  
Ray Dickens
Keyword(s):  
Water Stress ◽  
Seed Germination ◽  
Germination Rate ◽  
Stress Conditions ◽  
Continuous Darkness ◽  
Virginia Buttonweed ◽  
Osmotic Potentials ◽  
Diodia Virginiana

Virginia buttonweed seeds germinated at temperatures between 15 and 40 C, with optimal germination occurring at 25 or 30 C in 12 h light alternated with 15 to 25 or 20 to 30 C in darkness, respectively. Germination rate was lower in continuous darkness than in light. Germination was reduced under simulated water stress conditions with less than 10% of seeds germinating at osmotic potentials below −0.3 MPa. Overall seed germination was reduced under simulated flooding conditions; greater germination occurred in aerated water than in unaerated water. Maximum germination occurred at pH 6. Seedlings emerged from depths as great as 8 cm, with maximum emergence occurring from 2 cm.

scholarly journals Municipal Solid Waste (MSW) Compost Maturity Influence on Weed Seed Germination

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 577e-577 ◽  
Author(s):  
Monica Ozores-Hampton ◽  
Thomas A. Bewick ◽  
Peter Stoffella ◽  
Daniel J. Cantliffe ◽  
Thomas A. Obreza
Keyword(s):  
Seed Germination ◽  
Root Growth ◽  
Germination Rate ◽  
Petri Dish ◽  
Dry Weight ◽  
Germination Percentage ◽  
Maturity Stage ◽  
Weed Species ◽  
Compost Maturity ◽  
Yellow Nutsedge

The influence of compost (derived from MSW and biosolids) maturity on seed germination of several weed species was evaluated. A bioassay was developed by extracting 20 g of compost of different maturities with various volumes of water, then measuring germination percentage of ivyleaf morningglory (Ipomoea hederacea) seeds placed on extract-saturated filter paper in a petri dish. A 20 g (dry weight) compost: 50 mL of water generated an extract that produced the widest percentage seed germination variation in response to composts of different maturity. Ivyleaf morningglory, barnyardgrass (Echinochloa crus-galli L.), purslane (Potulaca oleracea L.), and corn (Zea mays L) were selected as plant indicators to determine the compost maturity stage with maximum germination inhibition. Compost 8-week-old decreased percent germination, root growth, and germination index (combines germination rate and root growth), and increased mean days to germination (MDG) of each plant indicator. Immature 8 week-old compost extract effect on MDG and germination percent of 15 weed species was evaluated. Extract from 8-week-old compost inhibited germination in most weed species, except yellow nutsedge (Cyperus esculentus). Compost extracts derided from immature (3-day, 4-, and 8-week-old) compost resulted in delayed and reduced germination percent of important economic weed species.

scholarly journals Heat shock and plant leachates regulate seed germination of the endangered carnivorous plant <i>Drosophyllum lusitanicum</i>

Web Ecology ◽  
2018 ◽  
Vol 18 (1) ◽  
pp. 7-13 ◽  
Author(s):  
Susana Gómez-González ◽  
Maria Paniw ◽  
Kamila Antunes ◽  
Fernando Ojeda
Keyword(s):  
Heat Shock ◽  
Seed Germination ◽  
Seed Dormancy ◽  
Fire Ecology ◽  
Germination Rate ◽  
Natural Populations ◽  
Seed Viability ◽  
Carnivorous Plant ◽  
In Fire

Abstract. In fire-prone ecosystems, many plant species have specialized mechanisms of seed dormancy that ensure a successful recruitment after fire. A well-documented mechanism is the germination stimulated by fire-related cues, such as heat shock and smoke. However, less is known about the role of inhibitory germination signals (e.g. allelopathy) in regulating post-fire recruitment. Plant leachates derived from the unburned vegetation can enforce dormancy by means of allelopathic compounds, acting as a signal of unfavourable (highly competitive) niche for germination in pyrophyte species. Here, we assessed the separate effects of heat shock and plant leachates on seed germination of Drosophyllum lusitanicum, an endangered carnivorous plant endemic to Mediterranean fire-prone heathlands. We performed a germination experiment in which seeds were subjected to three treatments: (1) 5 min at 100 ∘C, (2) watering with plant leachate, and (3) control. Germination rate and seed viability was determined after 63 days. Heat shock stimulated seed germination in D. lusitanicum while plant leachates had inhibitory germination effects without reducing seed viability. Thus, both positive and negative signals could be involved in its successful post-fire recruitment. Fire would break seed dormancy and stimulate seed germination of D. lusitanicum through high temperatures, but also by eliminating allelochemical compounds from the soil. These results help to understand the population dynamics patterns found for D. lusitanicum in natural populations, and highlight the role of fire in the ecology and conservation of this endangered species. Seed dormancy imposed by plant-derived leachates as an adaptive mechanism should be considered more in fire ecology theory.

scholarly journals TEMPERATURE, LIGHT, AND DESICCATION TOLERANCE IN SEED GERMINATION OF Mauritia flexuosa L.F.

2018 ◽  
Vol 42 (3) ◽  
Author(s):  
Lívia Caroline Praseres de Almeida ◽  
Kathia Fernandes Lopes Pivetta ◽  
Renata Gimenes ◽  
Gustavo de Nobrega Romani ◽  
Marcos Vieira Ferraz ◽  
...  
Keyword(s):  
Seed Germination ◽  
Desiccation Tolerance ◽  
Polynomial Regression ◽  
Germination Rate ◽  
Ornamental Plants ◽  
Effect Of Temperature ◽  
Randomized Experiments ◽  
Light Regimes ◽  
Palm Trees ◽  
Mauritia Flexuosa

ABSTRACT Palm trees are widely used as ornamental plants, besides its sustainability and industry aspects. These plants are commercially propagated via seeds. Due to its importance and the need for seed germination information, this study aimed to verify the effect of temperature, light regimes, and desiccation tolerance on germination of Mauritia flexuosa L.f. For that, two completely randomized experiments were carried out. The first consisted of treatments arranged in a 6 x 2 factorial scheme, testing six temperatures (20, 25, 30, 35, 20-30, and 25-35 ºC) and light presence and absence. The second comprised five seed water contents (51, 48, 45, 30, and 26%) for desiccation tolerance evaluations. Water content measurements were made every three days, from a sample lot maintained at room temperature. In both trials, each treatment was composed of four replicates with 25 seeds per plot. Germination rate (GR) and germination speed index (GSI) were calculated, and the data were analyzed by analysis of variance (ANOVA). Temperature and light means were compared by the Tukey’s test (p < 0.05), and the desiccation ones by a polynomial regression. The highest GR was observed at 20-30 ºC, regardless of light presence. Moreover, M. flexuosa seeds were sensitive to desiccation.

scholarly journals Aspectos sobre el control de malezas compuestas en pastos dedicados a la ganadería de leche

2004 ◽  
Vol 5 (1) ◽  
pp. 76
Author(s):  
Juan Manuel Arrieta Herrera
Keyword(s):  
Seed Germination ◽  
Weed Management ◽  
Management Practices ◽  
Picolinic Acid ◽  
Weed Species ◽  
Sonchus Oleraceus ◽  
Cultural Methods ◽  
High Soil Moisture ◽  
Potential Methods ◽  
Senecio Inaequidens

<p>Con el objeto de encontrar métodos de control oportunos y eficientes de <em>Senecio inaequidens </em>y <em>Sonchus oleraceus</em>, se desarrollaron una serie de observaciones sobre la ecofisiología y morfología de estas especies de malezas y se probaron algunos métodos de control cultural, químico y biológico. Los resultados mostraron que la edad de la semilla, la cantidad y calidad de la luz percibida, tienen una incidencia proporcional sobre la tasa de germinación. La relación entre la temperatura día/noche es inversamente proporcional a la producción de capítulos florales y hojas, con óptimos entre 20°/15° C. Al analizar la curva fenológica de <em>S. inaequidens</em>, se encontró que los 40 días es la época óptima de contro, mientras que a los 50 días la planta toma la forma de roseta y adquiere resistencia bioquímica a grandes grupos de herbicidas. Los resultados indican que el crecimiento y desarrollo de <em>S. inaequidens </em>se incrementa bajo condiciones de alta humedad del suelo, de allí que esta especie coloniza fácilmente bordes de canales y áreas inundadas en lotes agrícolas. En cuanto al control químico, <em>S. inaequidens </em>es una especie cuyo estado adulto es muy tolerante al amplio grupo de herbicidas derivados de los fenoxidos, del ácido benzoico, del ácido picolínico y de las isoxazolidinonas. Cuando se usaron algunos métodos mecá­nicos en la preparación del suelo, para el manejo del banco de semillas de malezas, el renovador de praderas redujo en un 23% el número de semillas; posteriormente se realizan dos pases de guadaña cada 45 días para cortar la floración de la maleza que emerge posteriormente; la reducción fue de 20% más. En cuanto al control biológico se encontraron dos especies de insectos: <em>Homeosoma oconoquensis </em>y <em>Ensina hyallipennis</em>, cuya actividad redujo en más de 50% las poblaciones de <em>Senecio inaequidens </em>y <em>Sonchus oleraceus</em>, siendo su incidencia y severidad mayor en el segundo semestre del año. La información generada permite suponer que los parámetros morfológicos y ecofisio­lógicos analizados servirían como herramientas de conocimiento que, integradas con algunos métodos de manejo cultural, biológico y químico, conformarían un modelo para el control de estas especies de malezas en praderas de trópico alto.</p><p> </p><p class="Pa19"><strong>Control Studies on compositae weeds in highland pastures.</strong></p><p class="Default">A series of physiological and morpholo­gical studies was conducted to identify potential methods to control the weeds <em>Senecio inaequidens </em>and <em>Sonchus oleraceus </em>in highland pastures of the Colombian Andean Region. The effect of light as well as the day/night temperature ratios on the weed seed germination and weed growth was measured. Results indicated that seed age and both qua­lity and quantity of light affected the seed germination of both weed species. Day/light temperature ratio (with an optimum at 20/15°C) did not affect leaf or achene production. Based on phenological curves for these species it is recommended that control methods should be applied before 40 days after weed germination, since at this stage the weed control turns to be extremely difficult due to the formation of a roset­te structure that makes the plant more resistant to phenoxid, benzoic, picolinic acid, and isoxazolidone herbicides. This study also indicated that senecio’s growth and development are favored by high soil moisture, which explains the invasive behavior of this weed on irrigation channels and flooded areas. Two cultural methods were tested to reduce the weed seeds in the soil. The “pasture renovator” system showed a 23% seed reduction, while mowing the pasture every 45 days resulted in a 20% seed reduction. Additionally two poten­tially useful biocontrol agents were identified: <em>Homeosoma oconequensis </em>and <em>Ensina Hyallipennis </em>which reduced to 50 % or more the population of the two weeds. Results suggest that morpholo­gical and ecophysiological parameters could be used to design and develop weed management practices (cultural, chemical and biological), which could be integrated into an economically fea­sible weed management model.</p>

Factors effecting the germination and emergence of a rangeland weed; European heliotrope (Heliotropium europaeum L.)

2018 ◽  
Vol 40 (6) ◽  
pp. 583
Author(s):  
Talia Humphries ◽  
Friedrich F. Graz ◽  
Singarayer K. Florentine
Keyword(s):  
Heat Shock ◽  
Seed Germination ◽  
Osmotic Stress ◽  
Germination Rate ◽  
Seedling Emergence ◽  
Control Treatment ◽  
Research Station ◽  
Burial Depth ◽  
South Wales ◽  
Heliotropium Europaeum

European heliotrope (Heliotropium europaeum L.) is an important weed in semiarid and arid Australia, due to its toxicity to livestock and its ability to out-compete crops for water and soil nutrients. It is an ephemeral species; populations appear in high densities when conditions are favourable, but seeds remain dormant in the soil seedbank for extended periods of time. This study aimed to identify environmental factors that promoted the germination of this weed and factors that de-vitalise seeds. Seeds were collected from the Australian semiarid zone, at Nanya Research Station, New South Wales. The effects on seed germination and seedling emergence of H. europaeum of alternating temperature, photoperiod, drought, salinity, pH range, heat shock combined with smoke exposure, and burial depth were investigated. The highest germination rate was observed under the highest temperature regime, 30/20°C, under a photoperiod of 12h light and 12h dark. The weed germinated under moderate osmotic stress, but the highest germination occurred in the control treatment (no osmotic stress). The effect of salinity and pH on percentage germination was not significant. The effect of the heat shock and smoke treatment significantly reduced seed germination, with germination inhibited when seeds were exposed to 100°C for 3min. Burial depth had a significant effect on seedling emergence, with a burial depth of 0.5cm reducing the germination by ~20%. It is recommended that further research into using fire and tillage interventions for H. europaeum be explored, as these may be used to reduce the viable seedbank of this weed, allowing long-term control to be achieved.

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