A quantitative analysis of seed responses to cycle-doses of fluctuating temperatures in relation to dormancy: Development of a thermal time model forPolygonum aviculareL. seeds

Abstract

The sensitivity ofPolygonum aviculareL. seeds to the dormancy-breaking effect of cycle-doses of fluctuating temperature changes as seeds lose dormancy due to storage under stratification temperatures. Sensitivity changes during seed stratification were characterized by a decrease in the number of cycles required to saturate the germination response, and by a progressive loss of the requirement for temperature fluctuations for dormancy breakage in increasing fractions of the seed population. The rate of these changes was dependent on the temperature at which seeds were stored for stratification; lower storage temperatures produced higher rates of change than higher storage temperatures. Germination curves, obtained in response to the effect of fluctuating temperature cycle-doses for seeds stratified at variable temperatures and times of storage, were brought to a common stratification thermal time (Stt) scale by accumulating thermal time units under a threshold temperature for dormancy loss to occur. Results showed that those seeds that had accumulated similarSttunits during stratification under different storage temperatures presented a similar germination response. Therefore, response-curve functions were adjusted to germination data of exhumed seeds that had accumulated similarStt, obtaining a family of germination response curves in relation toSttaccumulation during storage. Based on these results, a simulation model was constructed relating dynamic changes in the parameters that determine germination response curves in relation toSttaccumulation. The model was tested against independent data, showing a good description of the dynamics of changes in the fraction of the seed population requiring temperature fluctuation for dormancy breakage as dormancy release progressed.

Incubation under fluctuating temperatures reduces mean base water potential for seed germination in several non-cultivated species

“…Moreover, the dormancy level of each population was probably different and, consequently, sensitivity to fluctuating temperatures might be also different (Batlla et al, 2003). This would explain why the C b (50) shifted to a different extent as a result of exposure to fluctuating temperatures in each set of experiments (Table 1 versus Fig.…”

Modelling Spanish black pine seedling emergence: Establishing management strategies for endangered forest areas

“…Moreover, germination is very responsive to temperature and much higher temperature regimes are required to stimulate the metabolic activity necessary for germination (Kozlowski, 2002). The variable Tem minAc (sum of minimum daily air temperatures) has a negative influence on Spanish black pine seed germination probability indicating that germination under field conditions would take place when the field temperature is higher and enters the thermal range within which germination can occur (Batlla et al, 2003).…”

Population‐based threshold models describe weed germination and emergence patterns across varying temperature, moisture and oxygen conditions

“…Temperature effects on germination was determined in 2010 on isothermal lanes of a thermogradient table set at 15, 22, 25, 28, 31, 35 and 40 °C, assuming sensitivity to temperature fluctuations was removed during dormancy breakage (Batlla, Verges & Benech‐Arnold ). For each population, sets of approximately 55 seeds were placed in three 3‐cm Petri dishes and covered in 2‐mL DI water.…”