Title

Estimation of base temperatures for nine weed species

Author Info

Scott J. Steinmaus, University of California - RiversideFollow
Timothy S. Prather, University of California Kearney Agricultural Center
Jodie S. Holt, University of California - Riverside

Recommended Citation

Postprint version. Published in Journal of Experimental Botany, Volume 51, Issue 343, February 1, 2000, pages 275-286.

NOTE: At the time of publication, the author Scott Steinmaus was not yet affiliated with Cal Poly.

The definitive version is available at https://doi.org/10.1093/jexbot/51.343.275.

Abstract

Experiments were conducted to test several methods for estimating low temperature thresholds for seed germination. Temperature responses of nine weeds common in annual agroecosystems were assessed in temperature gradient experiments. Species included summer annuals (Amaranthus albus, A. palmeri, Digitaria sanguinalis, Echinochloa crus-galli, Portulaca oleracea, and Setaria glauca), winter annuals (Hirschfeldia incana and Sonchus oleraceus), and Conyza canadensis, which is classified as a summer or winter annual. The temperature below which development ceases (T_base) was estimated as the x-intercept of four conventional germination rate indices regressed on temperature, by repeated probit analysis, and by a mathematical approach. An overall T_base estimate for each species was the average across indices weighted by the reciprocal of the variance associated with the estimate. Germination rates increased linearly with temperature between 15 °C and 30 °C for all species. Consistent estimates of T_base were obtained for most species using several indices. The most statistically robust and biologically relevant method was the reciprocal time to median germination, which can also be used to estimate other biologically meaningful parameters. The mean T_base for summer annuals (13.8 °C) was higher than that for winter annuals (8.3 °C). The two germination response characteristics, T_base and slope (rate), influence a species’ germination behaviour in the field since the germination inhibiting effects of a high T_base may be offset by the germination promoting effects of a rapid germination response to temperature. Estimates of T_base may be incorporated into predictive thermal time models to assist weed control practitioners in making management decisions.

Disciplines

Biology

Copyright

2000 Oxford University Press.

Publisher statement

This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Journal of Experimental Botany following peer review.