Survival of annual ryegrass (Lolium rigidum Gaud.) in a Mediterranean type environment. 1. Effect of summer grazing by sheep on seed numbers and seed germination in autumn

1977 ◽  
Vol 28 (1) ◽  
pp. 81 ◽  
Author(s):  
D Gramshaw ◽  
WR Stern
Keyword(s):  
Germination Rate ◽  
Seedling Emergence ◽  
Subterranean Clover ◽  
Soil Surface ◽  
Dry Weight ◽  
Annual Ryegrass ◽  
Grazing History ◽  
Total Dry Weight ◽  
Moisture Conditions ◽  
Summer Grazing

Annual ryegrass–subterranean clover pastures that produced about 5000 kg total dry weight per hectare and 23,500 ryegrass seed per sq metre in spring were grazed by sheep at different stocking rates during summer. Intensive stocking equivalent to about 3000 sheep days ha-1 reduced seed numbers by 20%. Under continuous grazing, about 70% of the seed produced in spring fell readily to the ground during summer. The remaining seed was firmly held in seed heads, and apparently sheep ate mainly this component. Less than 1% of the seed ingested was voided in the faeces. No significant changes in seed numbers over summer were observed in ungrazed pasture. Subsequently, at the break of season in autumn, germination of seeds was examined in situ near the soil surface. The summer grazing history of pastures influenced the percentage of seeds that germinated; more seeds germinated in heavily than in leniently grazed pastures. Whether the pasture was leniently or heavily grazed, there was little effect on germination of shed seeds. Seeds in seed heads were found to germinate more slowly than seeds shed to the soil surface. Seedling emergence in autumn was regulated mainly by the interrelationship between the germination rate of the seed population, depending on summer-early autumn rains, and the period for which favourable moisture conditions prevailed at the soil surface after rain began in autumn. In the field, temperature and light appeared to be unimportant in influencing germination at the break of season. Dynamics of seed and seedling numbers in annual ryegrass pastures in a Mediterranean type environment, particularly at the break of season, are discussed.

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.

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 Impact of Environmental Factors on Seed Germination and Seedling Emergence of White Clover (Trifolium repens L.)

Agronomy ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 190
Author(s):  
Lei Chu ◽  
Yiping Gao ◽  
Lingling Chen ◽  
Patrick E. McCullough ◽  
David Jespersen ◽  
...  
Keyword(s):  
Seed Germination ◽  
Environmental Factors ◽  
White Clover ◽  
Trifolium Repens ◽  
Germination Rate ◽  
Seedling Emergence ◽  
Soil Surface ◽  
High Sensitivity ◽  
Series Of Experiments ◽  
Trifolium Repens L

White clover (Trifolium repens L.) is cultivated as a forage crop and planted in various landscapes for soil conservation. There are numerous reports of failed white clover stands each year. A good understanding of the seed germination biology of white clover in relation to environmental factors is essential to achieve successful stand establishment. A series of experiments were conducted to investigate the impacts of light, temperature, planting depth, drought, and salt stress on seed germination and the emergence of white clover. White clover is negatively photoblastic, and seed germination averaged 63 and 66% under light and complete dark conditions 4 weeks after planting (WAP), respectively. Temperature affected the seed germination speed and rate. At 1 WAP, seeds incubated at 15 to 25 °C demonstrated a significantly higher germination rate than the low temperatures at 5 and 10 °C; however, the germination rate did not differ among the temperature treatments at 4 WAP. The results suggest that white clover germination decreases with increasing sowing depths, and the seeds should be sown on the soil surface or shallowly buried at a depth ≤1 cm to achieve an optimal emergence. White clover seeds exhibited high sensitivity to drought and salinity stress. The osmotic potential and NaCl concentration required to inhibit 50% seed germination were −0.19 MPa and 62.4 mM, respectively. Overall, these findings provide quantifiable explanations for inconsistent establishment observed in field conditions. The results obtained in this research can be used to develop effective planting strategies and support the successful establishment of white clover stands.

scholarly journals Pertumbuhan dan Produksi Dioscorea sansibarensis Pax pada Perlakuan Panjang lanjaran dan Waktu Batang Membelit*

2018 ◽  
Vol 45 (3) ◽  
pp. 249
Author(s):  
Solikin ,
Keyword(s):  
Block Design ◽  
Soil Surface ◽  
Dry Weight ◽  
Growth And Yield ◽  
Botanic Garden ◽  
Randomized Block Design ◽  
Two Factors ◽  
Main Plot ◽  
Total Plant ◽  
Total Dry Weight

Dioscorea is potentially used as staple food to support food security. The research was aimed to determine the effect of stake length and time of  stem twining  on  the growth of Dioscorea sansibarensis Pax. The experiment was conducted  in  Purwodadi Botanic Garden from December 2014 until May 2015 using split plot randomized block design consisted of two factors, i.e. the stake length and time of stem twining. The stake length was the main plot consisted of 150 cm, 100 cm and 50 cm above soil surface and without stake (control). The time of stem twining as subplots, i.e. stem twined early, twined at the time of 4 leaves stage, and twined at 8 leaves stage. Each combination of the treatments was replicated three times. The results showed that there was significant effect on the stake length  and the time of stem twining treatments on the plant growth and yield. The stake  length of 150 cm treatment produced the highest fresh tuber and total plant dry weight, i.e., 257.24 g and 132.77 g per plant, respectively. On the contrary, the plant without stake produced the lowest fresh tuber and  total dry weight of plant, i.e., 112.10 g and 48.65 g per plant, respectively.<br /><br />Keywords: biomass,leaf area, photosyntesis, tuber weight

scholarly journals Evaluation of Chickpea (Cicer arietinum L.) Genotypes for Quality Seedlings

1970 ◽  
Vol 8 (2) ◽  
pp. 108-116
Author(s):  
Shahrina Akhtar ◽  
Jalal Uddin Ahmed ◽  
Abdul Hamid ◽  
Md Rafiqul Islam
Keyword(s):  
Biomass Production ◽  
Plant Biomass ◽  
Function Analysis ◽  
Dominant Role ◽  
Seedling Emergence ◽  
Genotypic Variation ◽  
Dry Weight ◽  
Total Biomass ◽  
Maximum Variance ◽  
Total Dry Weight

A study was conducted to evaluate 100 chickpea genotypes to explore their genetic diversity in respect of emergence and growth attributes. A high genotypic variation was observed in the characters studied. The highest positive correlation corresponded to the root mass and total plant biomass of the seedlings. Seedling biomass production was highly subjective to seedling vigor. Using discriminant function analysis, the first two functions contributed 46.2 and 39.0%, and altogether 85.2% of the variability among the genotypes. Function 1 was positively related to dry weight of root and total plants. The character with the greatest weight on function 2 was seedling emergence rate. The total dry weight of seedlings played the most dominant role in explaining the maximum variance in the genotypes. The genotypes were grouped into six clusters. Each cluster had specific seedling characteristics and the clusters 5 and 6 were closely related and clearly separated from clusters 1 and 4 for their higher amount of root and total biomass production, and vigorous seedlings, where as, the genotypes in cluster 2 and 3 were intermediate. The genotypes in cluster 5 followed by cluster 6 appeared to be important resources for selecting and developing chickpea variety. Keywords: Chickpea; genotypes; seedling; quality DOI: 10.3329/agric.v8i2.7584 The Agriculturists 8(2): 108-116 (2010)

Effects of environmental factors on germination and emergence ofAmaranthus retroflexus

Weed Science ◽  
1999 ◽  
Vol 47 (5) ◽  
pp. 505-510 ◽  
Author(s):  
R. Ghorbani ◽  
W. Seel ◽  
C. Leifert
Keyword(s):  
Seed Germination ◽  
Control Strategies ◽  
Germination Rate ◽  
Soil Surface ◽  
Dry Weight ◽  
Amaranthus Retroflexus ◽  
Nitrogen Supply ◽  
Biological Weed Control ◽  
Detailed Knowledge ◽  
Different Temperatures

Detailed knowledge about the environmental conditions required for weed seed germination and establishment in soil is an important prerequisite for the development of integrated and biological weed control strategies. Germination and establishmentof Amaranthus retroflexuswere studied at different temperatures, planting depths, soil types, nitrogen supply, and water potentials. The minimum temperature for seed germination was > 5 C; maximum germination occurred between 35 and 40 C. At temperatures between 25 and 35 C, an additive effect on germination rate was observed when temperature and water availability were increased. For all soils tested, the percentage emergence of seeds placed on the soil surface and 4 cm deep was significantly lower than seeds placed between 0.5 and 3 cm. Emergence in the four sandy soils was generally greater than in the two heavier soils included in the study. There was a highly significant interaction between seed depth and soil type. Plant growth was also greatest in the lighter soils. Plant height, number of leaves, leaf area, fresh and dry weight, and nitrogen and carbon percentage in plant tissues ofA. retroflexusincreased significantly with increasing soil nitrogen supply.

scholarly journals Seedling emergence and early growth of Chinese fir under different light levels and seed positions: implications for natural regeneration

2018 ◽  
Vol 48 (9) ◽  
pp. 1034-1041 ◽  
Author(s):  
Bo Liu ◽  
Qingqing Liu ◽  
Stefani Daryanto ◽  
Xiangqing Ma ◽  
Si Guo ◽  
...  
Keyword(s):  
Natural Regeneration ◽  
Southern China ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Light Level ◽  
Early Growth ◽  
Chinese Fir ◽  
Light Levels ◽  
Light Requirements ◽  
Moisture Conditions

Chinese fir, Cunninghamia lanceolata (Lamb.) Hook. (Taxodiaceae), is an evergreen conifer primarily distributed in southern China. This species exhibits very poor natural regeneration, possibly due to low light and a thick litter layer. To improve the understanding of the natural regeneration capacity of Chinese fir, in this study, we conducted a shade house experiment to determine the optimum light requirements and seed positions for seedling emergence and early growth. The experiment involved five light levels (100%, 60%, 40%, 15%, 5% of full sunlight) and four seed positions (1 cm beneath the soil surface without litter, on the soil surface without soil–seed contact, on the soil surface and covered with litter, and 1 cm beneath the soil surface and covered with litter). Seedling emergence was highest at 5%–15% sunlight, whereas seedling height, root length, root mass, stem mass, leaf mass, and total mass were highest at 60% sunlight. For each light level, seed position significantly affected emergence and growth. The above-litter position inhibited seedling emergence and survival, while the below-litter position favored seedling emergence and early growth, particularly under high light levels. Based on these results, to enhance natural regeneration of Chinese fir, we recommend periodical thinning to increase light into the understory after successful seedling emergence. We also recommend sowing seeds deeper into the litter to improve soil contact and moisture conditions.

Japanese Foxtail (Alopecurus japonicus) Management in Wheat in China: Seed Germination, Seedling Emergence, and Response to Herbicide Treatments

2017 ◽  
Vol 32 (2) ◽  
pp. 211-220 ◽  
Author(s):  
Hengzhi Wang ◽  
Yizhao Huang ◽  
Lele Zhang ◽  
Weitang Liu ◽  
Jinxin Wang
Keyword(s):  
Seed Germination ◽  
Integrated Management ◽  
Germination Rate ◽  
Seedling Emergence ◽  
Dry Weight ◽  
Integrated Approach ◽  
Growth Stages ◽  
Ph Values ◽  
Grass Weed ◽  
Different Growth Stages

AbstractLittle information is published related to seed germination and seedling emergence of Japanese foxtail, a troublesome annual grass weed widely distributed in winter wheat fields in China. Three Japanese foxtail populations were studied under laboratory and greenhouse conditions, to determine the effects of different environmental factors on seed germination or seedling emergence. Chemical control is absolutely necessary in integrated management, and efficacy of POST herbicides against different growth stages of Japanese foxtail was evaluated. Germination rate was 90% or more when temperature ranged from 5 to 25 C, with germination onset shortened as temperature increased. Light was not required for germination to occur. For pH values ranging from 5 to10 there was no effect on seed germination. Japanese foxtail seed germination was sensitive to osmotic stress and completely inhibited at an osmotic potential of -1.1 MPa. The ‘1513’ population of Japanese foxtail demonstrated tolerance to soil salinity, with 98% germination at 80 mM NaCl compared with 25 and 40% germination for populations ‘1532’ and ‘1544’, respectively. High amounts of crop residue (10 t ha−1) suppressed Japanese foxtail emergence 38 to 55%. Germination of seeds placed at 160 C for 5 min was completely inhibited for dry seeds, with a similar effect at 130 C for pre-soaked seeds. Seed burial in the soil from 0 to 4 cm had no effect on seedling emergence, but burial at 7 cm completely inhibited seedling emergence. POST herbicides mesosulfuron-methyl (13.5 g ai ha−1), clodinafop-propargyl (67.5 g ai ha−1), pyroxsulam (13.5 g ai ha−1), pinoxaden (67.5 g ai ha−1) and isoproturon (1125 g ai ha−1) reduced plant dry weight 80% or more when applied at three- to seven-leaf stage, but control declined with application at later growth stages. The information from this study helps to develop an integrated approach to Japanese foxtail management.

scholarly journals Morphological Development of Pawpaw [Asimina triloba (L.) Dunal] during Seed Germination and Seedling Emergence

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 633c-633
Author(s):  
C.L.H. Finneseth ◽  
Desmond R. Layne ◽  
R.L. Geneve
Keyword(s):  
Seed Germination ◽  
Developmental Stages ◽  
Scientific Information ◽  
Seedling Emergence ◽  
Dry Weight ◽  
Morphological Development ◽  
Asimina Triloba ◽  
Radicle Protrusion ◽  
Total Dry Weight ◽  
Food Reserves

Little scientific information is available describing morphological development of pawpaw during seed germination. To provide this information, a study was designed to outline important developmental stages and describe seedling characteristics within each stage. Stratified pawpaw seeds were sown in vermiculite and germinated at 25°C in a growth chamber. Ten seedlings were randomly chosen and destructively harvested at 5-day intervals starting at radicle protrusion. Length (mm), fresh and dry weight, and percentage of total dry weight were determined for seedling components. Pawpaw seeds have a small rudimentary embryo with all food reserves stored in a ruminate endosperm. Dry weight measurements showed a dramatic reallocation of reserves from the storage tissue to developing seedling parts. Initial embryo length was less than 3 mm, but within 70 days seedlings exceeded 350 mm. Twelve days after planting, simultaneous radicle and cotyledon growth occurred (3.4 and 3.0 mm, respectively), but neither hypocotyl nor epicotyl was visible. Radicle protrusion was observed at 15 days with radicle, cotyledon and hypocotyl lengths increasing to 4.4, 4.0, and 3.2 mm, respectively. Endosperm comprised 99.1% of total dry weight at this stage. The hypocotyl hook emerged after 30 days and endosperm comprised 76.1% of total dry weight. Cotyledons reached maximum length (29.0 mm) at day 40 and the epicotyl was discernible. At 55 days, the seed coat containing cotyledons and residual endosperm abscised and the average radicle, hypocotyl and epicotyl lengths were 182.0, 61.1, and 7.3 mm, respectively. It is suggested that the cotyledons primary function is absorption of food reserves from the endosperm for transfer to the developing seedling.

scholarly journals Effects of cycocel priming on growth and early development of rapeseed under drought stress

2013 ◽  
Vol 5 (1) ◽  
pp. 5-18
Author(s):  
Alireza Pourmohammad ◽  
Fariborz Shekari ◽  
Veeda Soltaniband
Keyword(s):  
Germination Rate ◽  
Dry Weight ◽  
Germination Percentage ◽  
Percentage Germination ◽  
Stress Control ◽  
Positive Effects ◽  
The Third ◽  
Germination Characteristics ◽  
Three Stages ◽  
Total Dry Weight

Abstract An experiment was concluded to evaluate the effects of priming on germination characteristics and establishment of rapeseed seedlings during three stages. In the first and second stages of experiment, the effects at three factors vis: cultivars (RVS, Hayola), waterdeficit stress (Control,-6 and -12 bar) and cycocel treatment (dry seeds, 300, 600, 900, 1200 and 1500 μM) on germination and seedling growth of plant were assayed. The results showed that priming had positive effects on germination percentage, germination rate index, germination index, and radicle length under water-deficit conditions. RVS had greater efficiency than other cultivars. The third section of experiment revealed that the priming of RVS seeds improved the stem, root and dry weight, total dry weight as well as leaf number and area of seedlings.

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