scholarly journals TEMPERATURE - GERMINATION RESPONSES OF SUNFLOWER (Helianthus annuus L.) GENOTYPES / GERMINACION COMO REACCION A LA TEMPERATURA EN LOS GENOTIPOS DEL GIRASOL (Helianthus annuus L.) / GERMINATION - RÉACTION À LA TEMPÉRATURE DANS LES GÉNOTYPES DE TOURNESOL (Helianthus annuus L.)

Helia ◽  
2000 ◽  
Vol 23 (33) ◽  
pp. 97-104
Author(s):  
F.M. Khalifa ◽  
A.A. Schneiter ◽  
E.I. El Tayeb
Keyword(s):  
Seed Germination ◽  
Helianthus Annuus ◽  
Maximum Rate ◽  
Germination Rate ◽  
Thermal Time ◽  
Large Temperature ◽  
Climatic Zones ◽  
Helianthus Annuus L ◽  
Wide Range ◽  
Cardinal Temperature

SUMMARY Seed germination of six sunflower (Helianthus annuus L.) hybrids was investigated across a range of eleven constant temperatures between 5°C and 45°C. Large temperature differences in germination rate 1/t (d-1), cardinal temperature (°C) and thermal time θ (°cd) were observed among hybrids. Base temperatures (Tb) varied between 3.3°C and 6.7°C whereas maximum germination temperatures (Tm) varied between 41.7°C and 48.9°C. Final germination fraction was attained at 15°C - 25°C whereas the maximum rate of germination was attained at 30.4°C - 35.6°C. The maximum germination rate of hybrid USDA 894, the cultivar with the slowest germination rate, was only 50% of that of hybrid EX 47. The low Tb and high Tm of sunflower appear to be one of the factors which explain the successful adaptation of sunflower to a wide range of temperature. These findings are discussed in relation to the origin of the crop and its wide adaptations in diverse habitats and climatic zones.

Effect of Environmental Factors on Germination and Emergence of Shortawn Foxtail (Alopecurus aequalis)

Weed Science ◽  
2017 ◽  
Vol 66 (1) ◽  
pp. 47-56 ◽  
Author(s):  
Ning Zhao ◽  
Qi Li ◽  
Wenlei Guo ◽  
Lele Zhang ◽  
Lu’an Ge ◽  
...  
Keyword(s):  
Seed Germination ◽  
Osmotic Potential ◽  
Control Strategies ◽  
Abiotic Factors ◽  
Germination Rate ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Burial Depth ◽  
Effective Measure ◽  
Wide Range

Shortawn foxtail is an invasive grass weed infesting winter wheat and canola production in China. A better understanding of the germination ecology of shortawn foxtail would help to develop better control strategies for this weed. Experiments were conducted under laboratory conditions to evaluate the effects of various abiotic factors, including temperature, light, pH, osmotic stress, salt concentration, and planting depth, on seed germination and seedling emergence of shortawn foxtail. The results showed that the seed germination rate was greater than 90% over a wide range of constant (5 to 25C) and alternating (15/5 to 35/25C) temperatures. Maximum germination occurred at 20C or 25/15C, and no germination occurred at 35C. Light did not appear to have any effect on seed germination. Shortawn foxtail germination was 27% to 99% over a pH range of 4 to 10, and higher germination was obtained at alkaline pH values ranging from 7 to 10. Seed germination was sensitive to osmotic potential and completely inhibited at an osmotic potential of −0.6 MPa, but it was tolerant to salinity: germination even occurred at 200 mM NaCl (5%). Seedling emergence was highest (98%) when seeds were placed on the soil surface but declined with the increasing burial depth. No seedlings emerged when seeds were buried 6-cm deep. Deep tillage could be an effective measure to limit seed germination from increased burial depth. The results of this study will lead to a better understanding of the requirements for shortawn foxtail germination and emergence and will provide information that could contribute to its control.

scholarly journals Seed Germination and Physiological Response of Sunflower (Helianthus annuus L.) Cultivars under Saline Conditions

2018 ◽  
Vol 75 (1) ◽  
pp. 4
Author(s):  
Carmen BEINSAN ◽  
Renata SUMALAN ◽  
Giancarla VELICEVICI ◽  
Adriana CIULCA ◽  
Radu SUMALAN
Keyword(s):  
Seed Germination ◽  
Helianthus Annuus ◽  
Dry Matter ◽  
Saline Stress ◽  
Free Proline ◽  
Radicle Growth ◽  
Helianthus Annuus L ◽  
Control Seed ◽  
Germination Process

The purpose of the experiment was to highlight the germination of sunflower seeds affected by the presence of saline stress and the identification of tolerant genotypes. The biological material was represented by sunflower cvs. (Helianthus annuus L.): Coril, Select, Santiago and Fundulea-206. To simulate the saline conditions, germination solutions of sodium chloride (NaCl) were used with concentrations corresponding to the osmotic pressures -6 and -10 atm and the control seed hydration was performed with distilled water. Determination of seed germination, growth of seedling, percentage of plumules dry matter, chlorophyll content and free proline were performed. The experimental data obtained suppose the existence in the assimilation apparatus of sunflowers seedling subjected to stress a competitive chlorophyll/free proline biosynthesis processes. The experimental results regarding the effect of salinity on seed germination and seedling growth revealed important differences between genotypes. The radicle growth in the germination process were strongly affected by saline excess, with significant differences between cultivars. Saline stress results in significant reductions in the amount of chlorophyll, and high levels of free proline. It can be observed that with the increase of the stress level the percentage of the dry matter increases, indicating an accentuated water deficit.

scholarly journals A Salt Tolerance Evaluation Method for Sunflower (Helianthus annuus L.) at the Seed Germination Stage

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Wenhui Li ◽  
Huizhen Zhang ◽  
Youling Zeng ◽  
Lijun Xiang ◽  
Zhonghua Lei ◽  
...  
Keyword(s):  
Salt Tolerance ◽  
Seed Germination ◽  
Helianthus Annuus ◽  
Evaluation Method ◽  
Helianthus Annuus L ◽  
Germination Stage

scholarly journals Pre-Sowing Treatments Improve Germinability of South Texas Native Plant Seeds

Plants ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2545
Author(s):  
Kaitlynn Lavallee ◽  
Pushpa Gautam Soti ◽  
Hansapani Rodrigo ◽  
Rupesh Kariyat ◽  
Alexis Racelis
Keyword(s):  
Seed Germination ◽  
Plant Species ◽  
Native Plants ◽  
Germination Rate ◽  
South Texas ◽  
Cold Stratification ◽  
Native Plant ◽  
Native Plant Species ◽  
Plant Seeds ◽  
Wide Range

The incorporation of native plant species is central to restoration efforts, but this is often limited by both the availability of seeds and the relatively low viability and germination rates of commercially available seeds. Although pre-sowing treatments are commonly used to improve germination rates of seeds, the efficacy of these treatments is found to vary across species. In this study, we tested how four pre-sow treatments (physical scarification, acid scarification, cold stratification, and aerated hydropriming) affected the viability and seed germination rates of 12 commercially available plant species native to south Texas and commonly used in restoration efforts. Our results show that the viability of the seeds have a wide range, from 78% to 1.25%. Similarly, the total germination rate ranged from 62% to 0%. We found that pre-sowing treatments accelerated the germination rate in 9 of 12 plant species tested, but the effect varied by treatment. Collectively, our results identify various methods to achieve the best germination rates for native plants of south Texas, to help improve restoration efforts across the region.

Temperature- and moisture-dependent models of seed germination and shoot elongation in green and redroot pigweed (Amaranthus powellii, A. retroflexus)

Weed Science ◽  
1997 ◽  
Vol 45 (4) ◽  
pp. 488-496 ◽  
Author(s):  
Joseph O. E. Oryokot ◽  
Stephen D. Murphy ◽  
A. Gordon Thomas ◽  
Clarence J. Swanton
Keyword(s):  
Seed Germination ◽  
Water Potential ◽  
Weed Management ◽  
Germination Rate ◽  
Shoot Elongation ◽  
Thermal Time ◽  
Base Temperature ◽  
Mathematical Function ◽  
Redroot Pigweed ◽  
Mean Temperature

To predict weed emergence and help farmers make weed management decisions, we constructed a mathematical model of seed germination for green and redroot pigweed based on temperature and water potential (moisture) and expressing cumulative germination in terms of thermal time (degree days). Empirical observations indicated green pigweed germinated at a lower base temperature than redroot pigweed but the germination rate of redroot pigweed is much faster as mean temperature increases. Moisture limitation delayed seed germination until 23.8 C (green pigweed) or 27.9 (redroot pigweed); thereafter, germination was independent of water potential as mean temperatures approached germination optima. Our germination model, based on a cumulative normal distribution function, accounted for 80 to 95% of the variation in seed germination and accurately predicted that redroot pigweed would have a faster germination rate than green pigweed. However, the model predicted that redroot pigweed would germinate before green pigweed (in thermal time) and was generally less accurate during the early period of seed germination. The model also predicted that moisture limitation would increase, rather than delay, seed germination. These errors were related to the mathematical function chosen and analyses used, but an explicit interaction term for water potential and temperature is also needed to produce an accurate model. We also tested the effect of mean temperature on shoot elongation (emergence) and described the relationship by a linear model. Base temperatures for shoot elongation were higher than for seed germination. Shoot elongation began at 15.6 and 14.4 C for green and redroot pigweed, respectively; they increased linearly with temperature until the optimum of 27.9 C was reached. Elongation was dependent on completion of the rate-limiting step of radicle emergence and was sensitive to temperature but not moisture; hence, elongation was sensitive to a much smaller temperature range. Beyond mathematical changes, we are testing our model in the field and need to link it to ecophysiological, genetic, and spatially explicit population processes for it to be useful in decision support for weed management.

scholarly journals Substrate moisture and temperature in Cajanus cajan (L.) Millspaugh germination

2017 ◽  
Vol 38 (4Supl1) ◽  
pp. 2375
Author(s):  
Edlânia Maria de Souza ◽  
Edna Ursulino Alves ◽  
Maria Lúcia Maurício da Silva ◽  
Luciana Rodrigues de Araújo ◽  
Maria Das Mercês Serafim dos Santos Neta
Keyword(s):  
Seed Germination ◽  
Cajanus Cajan ◽  
Germination Rate ◽  
Dry Weight ◽  
Mineral Nutrient ◽  
Seedling Vigor ◽  
Local Climate ◽  
Climate Conditions ◽  
Wide Range ◽  
Water Volumes

Cajanus cajan (L.) Millspaugh, a member of the Fabaceae, is commonly known as feijão-guandu. It was introduced into Brazil because it readily adapts to local climate conditions and tolerates a wide range of water and mineral nutrient levels. The objective of this study was to determine the substrate temperatures and water volumes that are conducive to feijão-guandu seed germination and seedling vigor. The experiment was conducted at the Laboratory of Seed Analysis of the Centre of Agricultural Sciences, Federal University of Paraíba, Areia, PB, Brazil. Seed germination was tested using paper towel rolls moistened with volumes of water equivalent to 2, 2.5, 3, 3.5, and 4 times the dry mass of the substrate. Variable temperatures in the range of 20 °C to 30 °C and constant temperatures of 25 °C, 30 °C, and 35 °C were used. The experimental design was completely randomized. The variables analyzed were water content, percent germination, first germination count, germination rate index, and seedling root and shoot lengths and dry weights. Increasing the volume of water used to moisten the substrate hindered feijão-guandu germination at all temperatures. It was determined that moistening the substrate with water volumes equivalent to 2.8 and 3.5 times the substrate dry weight at 30 °C and 35 °C, respectively, were the ideal conditions for evaluating feijão-guandu seed germination and seedling vigor.

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