Seed Germination and Seedling Recruitment Behavior of Winged Sea Lavender (Limonium lobatum) in Southern Australia

Weed Science ◽  
2018 ◽  
Vol 66 (4) ◽  
pp. 485-493 ◽  
Author(s):  
Samuel G. L. Kleemann ◽  
Gurjeet Gill
Keyword(s):  
Seed Germination ◽  
Seedling Recruitment ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Base Temperature ◽  
Weed Species ◽  
Factors Affecting ◽  
Weed Seeds ◽  
Sea Lavender ◽  
C 50

AbstractWinged sea lavender [Limonium lobatum(L.f. Chaz)] is emerging as a significant weed of field crops in southern Australia. Several environmental factors affecting germination and seedling recruitment were examined to provide a better understanding of the behavior of its seedbank. At maturity, weed seeds were dormant for a period of around 2 mo, but dormancy was easily broken with scarification or by pretreatment with 564 mM NaOCL for 30 min, which confirms the role of the seed coat in regulating seed germination. Exposure to light significantly increased germination. Seeds were able to germinate over a broad range of temperatures (5 to 30 C), with maximum germination (~92%) at temperatures between 10 and 30 C. At 20 to 25 C, 50% germination was reached within 1.3 to 2 d, and the predicted base temperature for germination of the two populations ranged from 1.4 to 3.9 C. The NaCl concentration required to inhibit germination by 50% was 230 mM, with some seeds capable of germination at salinity levels as high as 480 mM. These results indicated greater tolerance to salinity inL. lobatumthan many other Australian agricultural weed species previously investigated. Seedling emergence was the highest (51% to 57%) for seeds present on the soil surface and was significantly reduced by burial at 1 cm (≤11%) and 2 cm (≤2%), with no emergence at 5 cm. Under field conditions, seedling recruitment varied considerably among the three experimental sites. The level of seedling recruitment was negatively associated with rainfall received at the site, organic carbon (OC) level, and microbial biomass of the soil. Rapid decay of weed seeds in high-OC soils appears to be an important determinant of seedling recruitment in this species and could explain greater occurrence ofL. lobatumon soils with low OC and low microbial activity in low-rainfall areas of southern Australia. Furthermore, many such soils in southern Australia are affected by salinity, which would enableL. lobatumto be more competitive with crops and other weeds present at a site.

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.

Factors affecting seed germination of annual sowthistle (Sonchus oleraceus) in southern Australia

Weed Science ◽  
2006 ◽  
Vol 54 (5) ◽  
pp. 854-860 ◽  
Author(s):  
Bhagirath S. Chauhan ◽  
Gurjeet Gill ◽  
Christopher Preston
Keyword(s):  
Seed Germination ◽  
Osmotic Potential ◽  
Field Experiments ◽  
Soil Depth ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Factors Affecting ◽  
Control Programs ◽  
Buried Seed ◽  
Ph Range

Annual sowthistle has become more abundant under no-till systems in southern Australia. Increased knowledge of germination biology of annual sowthistle would facilitate development of effective weed control programs. The effects of environmental factors on germination and emergence of annual sowthistle seeds were examined in laboratory and field experiments. Seeds of annual sowthistle were able to germinate over a broad range of temperatures (25/15, 20/12, and 15/9 C day/night temperatures). Seed germination was favored by light; however, some germination occurred in the dark as well. Greater than 90% of seeds germinated at a low level of salinity (40 mM NaCl), and some seeds germinated even at 160 mM NaCl (7.5%). Germination decreased from 95% to 11% as osmotic potential increased from 0 to −0.6 MPa and was completely inhibited at osmotic potential greater than −0.6 MPa. Seed germination was greater than 90% over a pH range of 5 to 8, but declined to 77% at pH 10. Seedling emergence was the greatest (77%) for seeds present on the soil surface but declined with depth, and no seedlings emerged from a soil depth of 5 cm. In another experiment in which seeds were after-ripened at different depths in a field, seed decay was greater on the soil surface than at 2 or 5 cm depth. At the end of the growing season, there was a much greater persistence of buried seed (32 to 42%) than seeds present on the soil surface (8%). Greater persistence of buried seed could be due to dormancy enforced by dark in this species.

Factors Affecting Buffalobur (Solanum rostratum) Seed Germination and Seedling Emergence

Weed Science ◽  
2009 ◽  
Vol 57 (5) ◽  
pp. 521-525 ◽  
Author(s):  
Shouhui Wei ◽  
Chaoxian Zhang ◽  
Xiangju Li ◽  
Hailan Cui ◽  
Hongjuan Huang ◽  
...  
Keyword(s):  
Seed Germination ◽  
Light Exposure ◽  
Soil Depth ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Distribution Area ◽  
Burial Depth ◽  
Weed Species ◽  
Continuous Darkness ◽  
Invasive Weed

Buffalobur is a noxious and invasive weed species native to North America. The influence of environmental factors on seed germination and seedling emergence of buffalobur were evaluated in laboratory and greenhouse experiments. The germination of buffalobur seeds occurred at temperatures ranging from 12.5 to 45 C, with optimum germination attained between 25 and 35 C. Buffalobur seeds germinated equally well under both a 14-h photoperiod and continuous darkness; however, prolonged light exposure (≥ 16 h) significantly inhibited the seed germination. Buffalobur seed is rather tolerant to low water potential and high salt stress, as germination was 28 and 52% at osmotic potentials of −1.1 MPa and salinity level of 160 mM, respectively. Medium pH has no significant effect on seed germination; germination was greater than 95% over a broad pH range from 3 to 10. Seedling emergence was higher (85%) for seeds buried at a soil depth of 2 cm than for those placed on the soil surface (32%), but no seedlings emerged when burial depth reached 8 cm. Knowledge of germination biology of buffalobur obtained in this study will be useful in predicting the potential distribution area and developing effective management strategies for this species.

Factors affecting seed germination, seedling emergence, and survival of texasweed (Caperonia palustris)

Weed Science ◽  
2004 ◽  
Vol 52 (6) ◽  
pp. 989-995 ◽  
Author(s):  
Clifford H. Koger ◽  
Krishna N. Reddy ◽  
Daniel H. Poston
Keyword(s):  
Seed Germination ◽  
Osmotic Potential ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Production Potential ◽  
Factors Affecting ◽  
Edaphic Conditions ◽  
Percent Germination ◽  
Ph Range ◽  
Constant Dark

Field, laboratory, and greenhouse experiments were conducted to determine the seed production potential and effect of environmental factors on germination, emergence, and survival of texasweed. Texasweed produced an average of 893 seed per plant, and 90% were viable. Seed exhibited dormancy, and prechilling did not release dormancy. Percent germination ranged from 56% for seed subjected to no prechilling to 1% for seed prechilled at 5 C for 140 d. Seed remained viable during extended prechilling conditions, with 80% of seed viable after 140 d of prechilling. Texasweed seed germinated over a range of 20 to 40 C, with optimum germination (54%) occurring with a fluctuating 40/30 C temperature regime. Seed germinated with fluctuating 12-h light/dark and constant dark conditions. Texasweed seed germinated over a broad range of pH, osmotic potential, and salt concentrations. Seed germination was 31 to 62% over a pH range from 4 to 10. Germination of texasweed ranged from 9 to 56% as osmotic potential decreased from − 0.8 MPa to 0 (distilled water). Germination was greater than 52% at less than 40 mM NaCl concentrations and lowest (27%) at 160 mM NaCl. Texasweed seedlings emerged from soil depths as deep as 7.5 cm (7% emergence), but emergence was > 67% for seed placed on the soil surface or at a 1-cm depth. Texasweed seed did not germinate under saturated or flooded conditions, but seed survived flooding and germinated (23 to 25%) after flood removal. Texasweed seedlings 2.5 to 15 cm tall were not affected by emersion in 10-cm-deep flood for up to 14 d. These results suggest that texasweed seed is capable of germinating and surviving in a variety of climatic and edaphic conditions, and that flooding is not a viable management option for emerged plants of texasweed.

Factors Affecting Seed Germination of Perennial Wall Rocket (Diplotaxis tenuifolia) in Southern Australia

Weed Science ◽  
2007 ◽  
Vol 55 (5) ◽  
pp. 481-485 ◽  
Author(s):  
Samuel G. L. Kleemann ◽  
Bhagirath S. Chauhan ◽  
Gurjeet S. Gill
Keyword(s):  
Osmotic Potential ◽  
Seedling Recruitment ◽  
Seedling Emergence ◽  
South Australia ◽  
Soil Surface ◽  
Burial Depth ◽  
Optimal Conditions ◽  
Factors Affecting ◽  
Depth Of Burial ◽  
Osmotic Potentials

Germination response of perennial wall rocket to temperature, light, osmotic potential, and depth of burial emergence was evaluated under controlled environmental conditions. The effect of seed burial depth on seedling recruitment in the field was also investigated at Roseworthy, South Australia. Under optimal conditions (30 C, light/dark) germination of perennial wall rocket was rapid, with 90% of seeds germinating within 48 h of imbibition. Germination was reduced (20%) at lower, suboptimal temperatures (10 to 20 C) when seeds of perennial wall rocket were exposed to light. Germination declined with increasing osmotic potential and was completely inhibited at osmotic potentials of −1.5 MPa. Perennial wall rocket emergence was greatest from seeds placed on the soil surface, but some seedlings (< 10%) emerged from a depth of 0.5 to 2 cm. Under both field and growth-cabinet conditions, the greatest seedling emergence of perennial wall rocket occurred from seed present on the soil surface; however, the level of absolute recruitment from the seed bank was much lower (< 5%). Information gained from this study will further improve our understanding of the germination behavior of perennial wall rocket and contribute to developing sustainable strategies for its control.

Growth, Development, and Seed Biology of Feather Fingergrass (Chloris virgata) in Southern Australia

Weed Science ◽  
2017 ◽  
Vol 65 (3) ◽  
pp. 413-425 ◽  
Author(s):  
The D. Ngo ◽  
Peter Boutsalis ◽  
Christopher Preston ◽  
Gurjeet Gill
Keyword(s):  
Seedling Emergence ◽  
Soil Surface ◽  
Summer Rainfall ◽  
Management Program ◽  
Field Conditions ◽  
Shoot Biomass ◽  
Base Temperature ◽  
Weed Species ◽  
Seed Biology ◽  
Growth Development

Feather fingergrass is a major weed in agricultural systems in northern Australia and has now spread to southern Australia. To better understand the biology of this emerging weed species, its growth, development, and seed biology were examined. Under field conditions in South Australia, seedlings that emerged after summer rainfall events required 1,200 growing degree days from emergence to mature seed production and produced 700 g m−2shoot biomass. Plants produced up to 1,000 seeds panicle−1and more than 40,000 seeds plant−1, with seed weight ranging from 0.36 to 0.46 mg. Harvested seeds were dormant for a period of about 2 mo and required 5 mo of after-ripening to reach 50% germination. Freshly harvested seed could be released from dormancy by pretreatment with 564 mM sodium hypochlorite for 30 min. Light significantly increased germination. Seed could germinate over a wide temperature range (10 to 40 C), with maximum germination at 15 to 25 C. At 20 to 25 C, 50% germination was reached within 2.7 to 3.3 d, and the predicted base temperature to germinate was 2.1 to 3.0 C. The osmotic potential and NaCl concentration required to inhibit germination by 50% were −0.16 to −0.20 MPa and 90 to 124 mM, respectively. Seedling emergence was highest (76%) for seeds present on soil surface and was significantly reduced by burial at 1 (57%), 2 (49%), and 5 cm (9%). Under field conditions, seeds buried in the soil persisted longer than those left on the soil surface, and low spring–summer rainfall increased seed persistence. This study provides important information on growth, development, and seed biology of feather fingergrass that will contribute to the development of a more effective management program for this weed species in Australia.

scholarly journals Effect of Different Weed Management Strategies on Population Changing Pattern of Pennisetum polystachion in Coconut Plantations of Sri Lanka

CORD ◽  
2019 ◽  
Vol 35 (01) ◽  
pp. 8
Author(s):  
S.H.S. Senarathne
Keyword(s):  
Sri Lanka ◽  
Weed Management ◽  
Soil Seed Bank ◽  
Seedling Emergence ◽  
Management Strategies ◽  
Soil Surface ◽  
Weed Species ◽  
Cover Cropping ◽  
Weed Seeds ◽  
Weed Infestation

Pennisetum polystachion is a major problematic monocotyledonous weed species and a perennial problem in intermediate zone of coconut plantations in Sri Lanka. This study was carried out to evaluate the impacts of different management systems on P. polystachion seedling emergence patterns.The tested treatments were application of glyphosate (T1), cover cropping with Pueraria phaseoloides (T2), tractor harrowing (T3), tractor slashing (T4) and tractor ploughing (T5). All the treatments were applied twice a year except T2. As T2 cover crop at the initiation of the experiment and over grown conditions were managed by harrowing once a year. Based on the reduction in weed biomass, cover cropping (T2) was the best to reduce the P. polystachion population and to reduce P. polystachion seedling emergence density in the field. Chemical weeding was the second-best method to control the P. polystachion population in the field. The effectiveness of slashing in reducing weed seedling emergence density was lower than cover cropping and chemical weeding methods. The weed seedling emergence densities were almost similar in ploughed and harrowed plots. The seed depth of emerged seedling was very high in harrowed and ploughed treatments when compared to other treatments. Results given by T3 and T5 indicates that loosening the soil creates more favorable environment for the germination of weed seeds buried in soil. Therefore, it can be argued that the elimination of weed seeds in the top 2cm or 4cm in the soil seed bank by any means is likely to reduce the level of weed infestation by about 60% to 95%. Results also indicated that burying rhizomes in ploughing and harrowing treatment plots at the depths below 30 - 40 cm is effective in controlling germination of this weed species. This experiment also suggested that keeping rhizomes on the soil surface without burying for durations of 5 – 15 days would produce weak plants with poor development.

Seed Germination Ecology of Purple-Leaf Button Weed (Borreria ocymoides) and Indian Heliotrope (Heliotropium indicum): Two Common Weeds of Rain-Fed Rice

Weed Science ◽  
2008 ◽  
Vol 56 (5) ◽  
pp. 670-675 ◽  
Author(s):  
Bhagirath S. Chauhan ◽  
David E. Johnson
Keyword(s):  
Seed Germination ◽  
Seedling Emergence ◽  
Soil Layer ◽  
Soil Surface ◽  
Burial Depth ◽  
Light Conditions ◽  
Weed Species ◽  
Heliotropium Indicum ◽  
High Level ◽  
Purple Leaf

Purple-leaf button weed and Indian heliotrope are widespread and common weed species of rain-fed rice in many tropical countries. The influence of various environmental factors on seed germination of these species was studied. Seeds of both species germinated at a range of alternating temperatures (25/15, 30/20, and 35/25 C day/night). Germination of purple-leaf button weed was similar among light conditions after an after-ripening period of 3 mo, whereas germination of Indian heliotrope was always greater in light. Seed germination of both species was not affected by a high level of salt and a range of pH between 5 and 9, but was sensitive to high degrees of water stress. Seed burial strongly inhibited germination and emergence of these species. Seedling emergence of purple-leaf button weed (82 to 86%) and Indian heliotrope (70%) was optimal when seeds were sown in the top 0.2-cm soil layer. A burial depth of 2 cm completely inhibited emergence of Indian heliotrope, whereas, for purple-leaf button weed, this depth was 5 cm. Most of these seeds germinated, however, when brought to the soil surface. The information gained from this study would help in predicting the potential of these species for spreading into new areas, and could contribute to their control.

Environmental Factors Affecting Seed Germination and Seedling Emergence of Foxtail Sophora (Sophora alopecuroides)

Weed Science ◽  
2017 ◽  
Vol 66 (1) ◽  
pp. 71-77 ◽  
Author(s):  
Iraj Nosratti ◽  
Sahar Amiri ◽  
Alireza Bagheri ◽  
Bhagirath Singh Chauhan
Keyword(s):  
Seed Germination ◽  
Seedling Emergence ◽  
Farming Systems ◽  
Substantial Effect ◽  
Weed Species ◽  
Factors Affecting ◽  
Sophora Alopecuroides ◽  
Dryland Farming ◽  
No Till ◽  
Temperature Regimes

Foxtail sophora is a widely distributed problematic weed in western Iranian dryland farming systems. Little information is available on seed germination and seedling emergence of this weed species in response to environmental and agronomic factors. This study was conducted to address this knowledge gap. Maximum seed germination (80%) occurred at 25 C and decreased at lower temperatures (<1% at 5 C) or under fluctuating temperature regimes. Light and pH did not have any substantial effect on seed germination. Foxtail sophora was tolerant to osmotic stress and moderately tolerant to sodium chloride. It was tolerant to salinity and drought stress during germination, which suggests that the population of this weed may increase in western farmlands of Iran. No seedlings emerged when seeds were buried at depths greater than 6 cm, which indicates that minimum- and no-till systems would increase seedling emergence of this species. Therefore, using sweep cultivators would be beneficial in management of foxtail sophora seedlings in the drylands of west of Iran.

Tillage system effects on weed ecology, herbicide activity and persistence: a review

2006 ◽  
Vol 46 (12) ◽  
pp. 1557 ◽  
Author(s):  
B. S. Chauhan ◽  
G. S. Gill ◽  
C. Preston
Keyword(s):  
Seed Bank ◽  
Seedling Recruitment ◽  
Conservation Tillage ◽  
Soil Surface ◽  
Weed Species ◽  
Weed Ecology ◽  
Tillage Systems ◽  
Weed Seeds ◽  
Tillage System ◽  
The Impact

In the past few years, there has been a growing trend towards reducing tillage in cropping systems to allow stubble retention, earlier planting and improved soil structure. However, the adoption of conservation tillage systems will change weed control practices. Different tillage systems interact with the micro-environment of weed seeds and can influence the pattern of recruitment from the weed seed bank. Here, we present a review of the effect of different tillage systems on weed ecology, herbicide activity and herbicide persistence. Tillage systems can have a major influence on the vertical distribution of weed seeds in the soil seed bank. However, the impact of the changes in the vertical seed distribution on weed seedling recruitment is not well understood. Usually weed seedling recruitment increases if tillage equipment brings buried seed to, or close to, the soil surface, and seedling recruitment decreases if surface seed is buried deeper in the soil. However, tillage responses have a tendency to be species specific and can also be influenced by the intensity of tillage. Any weed species in which germination is stimulated by exposure to light is likely to become more prevalent under reduced tillage systems. Similarly, species that require burial for germination may become less prevalent. Crop residue present on the soil surface can also influence weed seedling recruitment by modifying the physical environment (mainly temperature) of weed seeds. Weed responses to plant residue could also be influenced by the allelopathic activity of the residue and the sensitivity of the weed species present. Few studies have investigated the fate of weed seeds that fail to germinate under any tillage system. Further research is needed to determine whether the weed seeds that fail to germinate decay before the start of the next growing season or become part of a persistent seed bank. Crop residues present on the soil surface can intercept a considerable amount of the applied herbicide and, depending on the herbicide, this intercepted component is susceptible to losses. Therefore, conservation tillage systems are expected to have lower efficacy of soil active herbicides. However, there has been little investigation of rate of loss of soil active herbicides under reduced tillage systems and the results reported have been inconsistent. Much of the research on these effects is from overseas and may not be true in Australian conditions. Therefore, further work is needed to clearly understand the impact of changing tillage systems on weed ecology, herbicide performance and persistence.

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