scholarly journals Using semi-natural and simulated habitats for seed germination ecology

2021 ◽  
Author(s):  
Simon Kallow ◽  
Katrijn Quaghebeur ◽  
Bart Panis ◽  
Steven Janssens ◽  
John B. Dickie ◽  
...  
Keyword(s):  
Seed Germination ◽  
Natural Habitat ◽  
Crop Wild Relatives ◽  
The Philippines ◽  
Maximum Temperature ◽  
Marginal Effect ◽  
Burial Depth ◽  
Natural Habitats ◽  
Seed Burial ◽  
Soil Temperatures

1. Ecologically meaningful seed germination experiments are constrained by access to seeds and relevant environments for testing at the same time. This is particularly the case when research is carried out far from the native area of the studied species. 2. Here, we demonstrate an alternative - the use of glass houses in botanic gardens as simulated-natural habitats to extend the ecological interpretation of germination studies. Our focal taxa were banana crop wild relatives (Musa acuminata subsp. burmannica, M. acuminata subsp. siamea and M. balbisiana), native to tropical and subtropical Southeast Asia. Tests were carried out in Belgium, where we performed germination tests in relation to exposure to sun and foliage-shading, seed burial-depth in different heated glass house compartments, as well as seed survival and dormancy release in the soil. We anchored the interpretation of these studies by also conducting an experiment in a semi-natural habitat in the species native range (M. balbisiana - Los Baños, the Philippines), where we tested germination responses to exposure to the sun and shade. Using temperature data loggers, we determined temperature dynamics suitable for germination in both these settings. 3. In semi-natural and simulated-natural habitats, seeds germinated in response to exposure to direct solar radiation. Seed burial-depth had a significant but marginal effect by comparison, even when seeds were buried to 7cm in the soil. Temperatures at sun-exposed compared to shaded environments differed by only a few degrees Celsius. Maximum temperature of the period prior to germination was the most significant contributor to germination responses and germination increased linearly above a threshold of 23°C to the maximum temperature in the soil (in simulated natural habitats) of 35°C. 4. Glass houses can provide useful environments to aid interpretation of seed germination responses to environmental niches.

Germination of Fresh Horse Purslane (Trianthema portulacastrum) Seeds in Response to Different Environmental Factors

Weed Science ◽  
2011 ◽  
Vol 59 (4) ◽  
pp. 495-499 ◽  
Author(s):  
Jihyun Lee ◽  
Bhagirath S. Chauhan ◽  
David E. Johnson
Keyword(s):  
Seed Germination ◽  
Environmental Factors ◽  
Seedling Emergence ◽  
Soil Surface ◽  
The Philippines ◽  
Integrated Weed Management ◽  
Burial Depth ◽  
Seed Burial ◽  
Soil Burial ◽  
Two Populations

Horse purslane, a C4 species, is a branched, prostrate, and annual weed of upland field crops throughout the tropics. Experiments were conducted to determine the influence of various environmental factors on seed germination and seedling emergence of two populations of horse purslane. Seeds were collected from rice fields of the International Rice Research Institute (the IR population) and from sorghum fields of the University of the Philippines (the UP population); the two sites were 5 km apart in Los Baños, Philippines. Germination response of both populations was greater at 30/20 C and35/25 C day/night temperatures than they were at 25/15 C alternating day/night temperatures. Germination of both populations was greater in the light/dark regime than in darkness. In dark, depending on the temperature, seed germination of the UP population ranged from 37 to 62%, whereas seed germination of the IR population was < 20%. Exposure to 5 min at 117 and 119 C for the IR and UP populations, respectively, reduced germination to 50% of maximum germination. Osmotic potential of −0.26 MPa inhibited germination to 50% of the maximum for the UP population, whereas the corresponding value for the IR population was −0.37 MPa. Seeds placed on or near the soil surface had maximum emergence, and emergence declined with increase in seed burial depth. Seedling emergence of the UP and IR populations was 74% and 13%, respectively, for seeds placed on the soil surface. For both populations, no seedlings emerged from a soil burial depth of 6 cm or more. Germination and emergence responses to light and seed burial depth differed between the two populations of horse purslane. Residues on the soil surface of up to 6 Mg ha−1 did not influence seedling emergence of either populations. Knowledge gained in this study could contribute to developing components of integrated weed management strategies for horse purslane.

Seed Germination Ecology of Itchgrass (Rottboellia cochinchinensis)

Weed Science ◽  
2011 ◽  
Vol 59 (2) ◽  
pp. 182-187 ◽  
Author(s):  
Grace E-K. Bolfrey-Arku ◽  
Bhagirath S. Chauhan ◽  
David E. Johnson
Keyword(s):  
High Temperature ◽  
Seed Germination ◽  
Seedling Emergence ◽  
Soil Surface ◽  
The Philippines ◽  
Integrated Weed Management ◽  
Burial Depth ◽  
Soil Burial ◽  
Dark Regime ◽  
Temperature Pretreatment

Itchgrass is a weed of many crops throughout the tropics and one of the most important grass weeds of rainfed rice. Experiments were conducted in the laboratory and screenhouse to determine the effects of light, alternating day/night temperatures, high temperature pretreatment, water stress, seed burial depth, and rice residue on seed germination and seedling emergence of itchgrass in the Philippines. Two populations were evaluated and the results were consistent for both populations. Germination in the light/dark regime was greater at alternating day/night temperatures of 25/15 C than at 35/25, 30/20, or 20/10 C. Light was not a requirement for germination, but a light/dark regime increased germination by 96%, across temperature and population. A 5-min high temperature pretreatment for 50% inhibition of maximum itchgrass germination ranged from 145 to 151 C with no germination when seeds were exposed to ≥ 180 C. The osmotic potential required for 50% inhibition of maximum germination was −0.6 MPa for itchgrass, although some seeds germinated at −0.8 MPa. Seedling emergence was greatest for seeds placed on the soil surface, and emergence declined with increasing soil burial depth; no seedlings emerged from seeds buried at 10 cm. The addition of rice residue to soil surface in pots at rates equivalent to 4 to 6 Mg ha−1reduced itchgrass seedling emergence. Since seedling emergence was greatest at shallow depths and germination was stimulated by light, itchgrass may become a problem in systems where soil is cultivated at shallow depths. Knowledge gained in this study could contribute to developing components of integrated weed management strategies for itchgrass.

Soil temperatures and seed burial in relation to the performance of Heteropogon contortus and Themeda australis in burnt native woodland pastures in Eastern Queensland

1969 ◽  
Vol 17 (2) ◽  
pp. 269 ◽  
Author(s):  
JC Tothill
Keyword(s):  
Ground Cover ◽  
Ground Level ◽  
Maximum Temperature ◽  
Seed Burial ◽  
Ambient Temperatures ◽  
Seasonally Dry ◽  
Heteropogon Contortus ◽  
Average Maximum ◽  
Soil Temperatures ◽  
Native Pastures

The factors underlying the increasing dominance of Heteropogon contortus (bunch or black spear grass) as a result of regularly burning native pastures in eastern Queensland have been investigated. In the subtropical environment of this experiment the removal of ground cover by burning or other means significantly increased the average maximum temperature of the surface soil. Burning favoured the germination of buried H. contortus seed at a time when ambient temperatures were too low for this to occur in unburnt situations. In late seasons and in the seasonally dry tropics insufficient soil moisture would tend to limit growth and germination until ambient temperatures are high, in which case the burning effect would be less pronounced. The efficient seed burial mechanism of H. contortus places it at an establishment advantage over other commonly associated species such as blue grasses (Bothriochloa, Dichanthium) and others whose seeds remain largely in the surface litter. Fire destroys much of this litter, the microhabitat for seed germination at ground level, and some of the weaker perennial plants. The implications of these results in relation to the increased dominance of either H. contortus or Themeda australis (kangaroo grass) are discussed.

scholarly journals Germination ecology of Rhynchosia capitata: an emerging summer weed in Asia

2013 ◽  
Vol 31 (2) ◽  
pp. 249-257 ◽  
Author(s):  
H.H. Ali ◽  
A. Tanveer ◽  
M.A. Nadeem ◽  
H.N. Asghar ◽  
M.M. Javaid
Keyword(s):  
Seed Germination ◽  
Soil Depth ◽  
Seedling Emergence ◽  
Ecological Factors ◽  
Moisture Stress ◽  
Burial Depth ◽  
Seed Burial ◽  
Germination Ability ◽  
Wide Range ◽  
The One

Rhynchosia capitata is becoming an increasing problem in summer crops, such as cotton, soybean, pearl millet and mungbean in many Asian countries. Laboratory and greenhouse studies have been conducted to determine the effects of several environmental factors on seed germination patterns and seedling emergence of R. capitata. We investigated whether the diverse ecological factors such as temperature, light, salinity, moisture stress, pH, and soil depth affected germination and seedling emergence of R. capitata. Germination increased as temperature increased from 25ºC and significantly reduced at 45ºC. Presence or absence of light did not influence germination. Germination of R. capitata was sensitive to increased salt and moisture stress, as well as to seed burial depth. Only 48% of seeds germinated at 150 mM salt concentration compared to 100% in control (distilled water). Similarly, 15% of seeds germinated at an osmotic potential of ‑0.8 MPa compared to 88% at ‑0.2 MPa. The optimum pH for seed germination of R. capitata was 7 (98% germination), but the seeds also germinated at lower level of pH 5 (85%) and at higher level of pH 10 (75%). In seed burial trial, maximum seedling emergence of 93% occurred at 2 cm depth, and seedling did not emerge from a depth of 12 cm. The high germination ability of R. capitata under a wide range of ecological factors suggests that this species is likely to be the one to cause more problems in a near future, if not managed appropriately.

Influence of flooding period and seed burial depth on Palmer amaranth ( Amaranthus palmeri ) seed germination

2020 ◽  
Vol 76 (11) ◽  
pp. 3832-3837
Author(s):  
Lucas X Franca ◽  
Darrin M Dodds ◽  
Daniel B Reynolds ◽  
Jason A Bond ◽  
Anthony Mills ◽  
...  
Keyword(s):  
Seed Germination ◽  
Palmer Amaranth ◽  
Burial Depth ◽  
Amaranthus Palmeri ◽  
Seed Burial ◽  
Flooding Period

Seed germination and seedling emergence of three Artemisia species (Asteraceae) inhabiting desert sand dunes in China

2006 ◽  
Vol 16 (1) ◽  
pp. 61-69 ◽  
Author(s):  
Kazuo Tobe ◽  
Liping Zhang ◽  
Kenji Omasa
Keyword(s):  
Seed Germination ◽  
Sand Dunes ◽  
Seedling Emergence ◽  
Light Sensitivity ◽  
Burial Depth ◽  
Secondary Effects ◽  
Seed Burial ◽  
Desert Sand ◽  
Light Fluence ◽  
Artemisia Species

Artemisia ordosica,A. arenariaandA. sphaerocephalaare semi-shrubs inhabiting desert sand dunes in China and often used to rehabilitate desertified areas. Improvement of dune rehabilitation success by sowing requires better understanding of the processes involved in the control of seed germination and seedling emergence in these species. Thus, (1) effects of temperature, light and osmotica (polyethylene glycol-6000) on seed germination, and (2) effects of seed burial depth in sand and irrigation regime on seedling emergence, were studied under controlled conditions. Seeds of the three species required light for germination, and the light fluence needed for germination was dependent on temperature. Seedling emergence of the three species was maximal (70–94%) for seeds sown at a depth of 2.5 mm, and decreased with increasing seed burial depth when the pots were initially and subsequently treated with 16 mm and 3 mm irrigation at 1-d intervals. However, when the pots were initially and subsequently treated with 8 mm and 3 mm irrigation at 2-d intervals, seedling emergence was almost completely suppressed due to water deficiency in sand. It is suggested that the probability of seed germination and seedling emergence of the three species in the field is very limited, because the light requirement restricts seed germination to shallow sand layers where water is lost rapidly due to evaporation. Temperature appeared to have secondary effects on seed germination, by modifying the light sensitivity of seeds.

Seed Germination Ecology of Junglerice (Echinochloa colona): A Major Weed of Rice

Weed Science ◽  
2009 ◽  
Vol 57 (3) ◽  
pp. 235-240 ◽  
Author(s):  
Bhagirath S. Chauhan ◽  
David E. Johnson
Keyword(s):  
Seed Germination ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Moisture Stress ◽  
The Philippines ◽  
Reduced Tillage ◽  
Burial Depth ◽  
Tillage Systems ◽  
Ph Range ◽  
The Tropics

Junglerice is one of the most serious grass weeds of rice in the tropics. Experiments were conducted in the laboratory and screenhouse to determine the influence of environmental factors on seed germination and seedling emergence of junglerice in the Philippines. In the laboratory, germination was stimulated by light, suggesting that seeds of this species are positively photoblastic. The tested temperatures (35/25, 30/20, and 25/15 C alternating day/night temperatures), however, did not influence germination. Germination in the laboratory was not affected by a soil pH range of 4 to 9, but was decreased by salinity (> 50 mM NaCl) and moisture stress (< −0.2 MPa osmotic potential). In the screenhouse, germination of junglerice was greatest (97%) for seeds at the soil surface, but emergence declined exponentially with increasing seed burial depth, and no seedlings emerged from seeds buried at 6 cm. In pots, seedling emergence declined markedly with the addition of rice residue to the soil surface at rates equivalent to 4 to 6 tonnes (t) ha−1. As germination of junglerice was strongly stimulated by light, and seedling emergence was optimal at shallow burial depths, this species is likely to be problematic in reduced tillage systems.

Crowfootgrass (Dactyloctenium aegyptium) Germination and Response to Herbicides in the Philippines

Weed Science ◽  
2011 ◽  
Vol 59 (4) ◽  
pp. 512-516 ◽  
Author(s):  
Bhagirath Singh Chauhan
Keyword(s):  
Seed Germination ◽  
Weed Management ◽  
Seedling Emergence ◽  
Management Strategies ◽  
Soil Surface ◽  
The Philippines ◽  
Integrated Weed Management ◽  
Burial Depth ◽  
Early Application ◽  
Dark Regime

Crowfootgrass, a C4species, is one of the principal weeds of dry-seeded rice in Asia. Weed management decisions for this species can be derived from knowledge of its seed germination biology. Experiments were conducted in the laboratory and screenhouse to determine the effects of light, alternating day/night temperatures, water stress, seed burial depth, and rice residue on seed germination and seedling emergence of crowfootgrass and to evaluate the response of this weed to commonly available selective POST herbicides in the Philippines. Light stimulated seed germination, but it was not an absolute requirement for germination. Germination in the light/dark regime was greater at alternating day/night temperatures of 25/15 C (92%) than at 30/20 (70%) or 35/25 C (44%). The osmotic potential required for 50% inhibition of maximum germination was −0.23 MPa, although some seeds germinated at −0.6 MPa. Seedling emergence was greatest for the seeds placed on the soil surface (64%), and emergence declined with increased burial depth in soil. No seedlings emerged from a burial depth of 6 cm or greater. Seedling emergence of crowfootgrass was reduced by the addition of rice residue to the soil surface at rates equivalent to 4 to 6 Mg ha−1. Fenoxaprop-p-ethyl + ethoxysulfuron at 45 g ai ha−1provided excellent control of crowfootgrass when applied at the four- (99%) and six-leaf (86%) stage. The information gained from this study could contribute to developing components of integrated weed management strategies for crowfootgrass. Soil inversion by tillage to bury weed seeds below their maximum depth of emergence, use of crop residue as mulch, and early application of an effective POST herbicide could serve as important tools for managing crowfootgrass.

scholarly journals ON THE CULTIVATION OF CAULERPA RACEMOSA VAR. OCCIDENTALIS IN THE PHILIPPINES AND SOME ASPECTS OF THE PHYSIOLOGICAL ECOLOGY

1970 ◽  
Vol 17 ◽  
pp. 143-144
Author(s):  
A. Colina ◽  
U. Horstman ◽  
W. Schramm
Keyword(s):  
Natural Habitat ◽  
Physiological Ecology ◽  
The Philippines ◽  
Extreme Conditions ◽  
Caulerpa Racemosa ◽  
Natural Habitats ◽  
Physiological Limits ◽  
Commercial Scale ◽  
Sublittoral Zone ◽  
Tropical Areas

Caulerpa racemosa, a benthic siphonaceous algae has its natural habitat in the sublittoral zone of tropical areas. In the Philippines, since a few years, it is cultivated on commercial scale in flooded ponds in the intertidal mangrove zone. Unlike in their natural habitats, Caulerpa in these ponds is subjected to sometimes considerable changes in salinity (rain, evaporation, tem-perature and light (Insolation), and in pH). The response of Caulerpa to these factors and the comparison of the ecological conditions, both in the natural habitats and the cultured ponds have been investigated. The experiments showed that the observed changes of the studied parameters normally range within the physiological limits of Caulerpa. Under extreme conditions, however, detri-mental effects can occur. Ways of controlling such factors are discussed.

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