Estimation of base and optimum temperatures for seed germination in common crupina (Crupina vulgaris)

Thermal time models for predicting phenological development require an estimate of base temperature, an attribute not previously defined for common crupina, a Mediterranean winter annual introduced in western North America. The stage of seed germination was selected for estimating base temperature,...

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Bibliographic Details
Published in:Weed science 1997-08, Vol.45 (4), p.529-533
Main Authors: Roché, Cindy Talbott, Thill, Donald C., Shafii, Bahman
Format: Article
Language:English
Subjects:
Achenes
Confidence interval
Crupina vulgaris
crupina vulgaris var. brachypappa
crupina vulgaris var. typica
Developmental biology
Ecological invasion
Germination
growth models
growth rate
heat sums
Mathematical extrapolation
mathematical models
phenology
Plants
prediction
Seed germination
Temperature gradients
weed biology
Weed Biology and Ecology
Wheat
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Summary:Thermal time models for predicting phenological development require an estimate of base temperature, an attribute not previously defined for common crupina, a Mediterranean winter annual introduced in western North America. The stage of seed germination was selected for estimating base temperature, because facilities were available for experiments over a range of constant temperatures and base temperature is relatively constant throughout the life cycle in other species. Achenes from three populations of common crupina, including two varieties, typica and brachypappa, were produced under uniform conditions. Cumulative germination was recorded at 12 h intervals for achenes in darkness and optimum moisture at 23 constant temperatures from 4 to 17 C. The time course of germination was best described by a logistic growth curve from which time to 50% germination was estimated. A parabolic model provided the best fit in a regression of germination rate (reciprocal of time to 50%) against the temperature gradient, yielding base and optimum temperatures of 1 and 10.5 C, respectively. Bootstrap confidence intervals indicated no significant difference in base and optimum temperatures in germination between the two varieties nor between two populations of var. typica of common crupina introduced in the northwestern United States.
ISSN:0043-1745
1550-2759
DOI:10.1017/S0043174500088767