Simulation of germination of winter annuals in relation to microclimate and microdistribution

Janssen, J. G. M.

doi:10.1007/bf01039793

Cited by 11 publications

(5 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In winter annuals, summer seed dormancy appears to be an adaptation which prevents germination during temporary moist periods in summer and thus allows the species to persist in hot, dry summer habitats (Ratcliffe, 1961;Newman, 1963;Thompson, 1970;Baskin and Baskin, 1971a;Hajkova and Krekule, 1972;Janssen, 1974). However, very little information is available concerning the effect of temperature on afterripening of the seeds.…”

Section: Introductionmentioning

confidence: 99%

High Temperature Requirement for Afterripening in Seeds of Winter Annuals

Baskin

1976

New Phytologist

View full text Add to dashboard Cite

SUMMARYTemperature requirements for afterripening were investigated in seeds of the winter annuals, Stellaria media., Valerianella umbilicata and Phacelia purshii. Seeds were incubated during the summer dormancy period at nine temperature regimes on wet and alternately wetted and dried sand. Low temperatures (5, 10, 15, 15/6 and 2o/io°C) inhibited and high temperatures (20, 25, 30/15 and 35/2o°C) promoted afterripening of the seeds. Temperatures (5 and io°C) which promote afterripening in species with a chilling requirement (e.g., summer annuals) almost completely prevented afterripening of the three winter annuals. Thus, although dormancy is an adaptation of winter annuals to their hot, dry summer habitat, the summer temperatures are required for afterripening of the seeds.

show abstract

Section: Introductionmentioning

confidence: 99%

High Temperature Requirement for Afterripening in Seeds of Winter Annuals

Baskin

1976

New Phytologist

View full text Add to dashboard Cite

show abstract

“…Many authors have devised indices of speed of germination to allow comparisons between populations (e.g.. Tucker & Wright 1965;Nichols & Heydecker 1968;Goodchild & Walker 1971;Janssen 1973). In the studies reported in this paper, the speed of germination is expressed as 'the percentage of non-dormant seed germinating in 12 h'.…”

Section: Methods and Resultsmentioning

confidence: 97%

Pasture seed dynamics in a dry monsoonal climate, II The effect of water availability, light and temperature on germination speed and seedling survival of Stylosanthes humilis and Digitaria ciliaris

McKeon

1985

Australian Journal of Ecology

View full text Add to dashboard Cite

Environmental factors affecting speed of germination and survival of naturally occurring seed of the legume Stylosanthes humilis and the grass Digitaria ciliaris were studied. Previous studies on the seedbed environment had shown that germination speed, defined as the proportion of seeds capable of germinating in the first 12 h period, was likely to be the most relevant laboratory measurement. Ten studies were conducted to compare species performance and to devise a starulard technique for the measurement of germination speed under laboratory coruiitions.Eor S. humilis, the level and duration of submergence in water in the germination test had a large effect on germination speed (from 0-70% in 12 h). The absence of light delayed germirmtion (7% in 12 h compared to 52% under light), but did not prevent complete germination over 7 days. Optimum temperature was 25°C with a decrease to 0% at 3(fC. A starulard technique was developed for measuring potential germination speed which gave reproducible results allowing differences in seed lots to be described.D. ciliaris seeds sampled just prior to field germination in the early storm period were less sensitive to environmental control. Temperature optimum for germination decreased from 40 to 3(fC with the duration of the germination test. Seeds sampled at the time of seed dispersal (early dry season) had a high fraction (80%) requiring light for germination but this requirement had been lost by the early storm period.Investigations on the role of leaching (water movement) showed that long periods of water * Present address: Agriculture Branch, Department of Primary Industries, GPO Box 46, Brisbane, Qld 4001, Australia movement (12-18 h) increased the speed of germination of both species and in the case ofS. humilis overcame environmental blocks to rapid germination (absence of light or 30°C temperature).Root elongation rates in S. humilis were not greatly affected by temperature over the range of seedbed temperatures when moisture is available in the field. However, D. ciliaris was delayed in development at 25°C, the most likely overnight surface soil temperature. D. ciliaris was more susceptible to death by desiccation once germination had occurred compared to S. humilis. In both species seedling death due to desiccation increased with stage of development.The better relative performance of S. humilis in the germination-establishment phase of the life cycle, which had been observed in a previous study, could be explained by a qualitative comparison of the species' attributes. This suggested that D. ciliaris was more likely to germinate at rainfall events following which there was a greater chance of seedling death.

show abstract

“…Yet another method for obtaining complex relationships is the use of a "black box" which simulates the relation between input and output, Janssen (1974) has used it in his model of germinating seeds of winter annuals. 19 All three methods described can be combined with statistical methods or the accuracy of the results can be compared with independently measured values.…”

Section: Evaluation Of Modelsmentioning

confidence: 99%