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Secondary dormancy, temperature, and burial depth regulate seedbank dynamics in canola

Published online by Cambridge University Press:  20 January 2017

Robert H. Gulden
Affiliation:
Department of Plant Sciences, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada
A. Gordon Thomas
Affiliation:
Agriculture and Agri-Food Canada, Saskatoon Research Centre, 107 Science Place, Saskatoon, SK S7N 0X2, Canada

Abstract

In western Canada, seasonal seedling recruitment has been reported in weedy canola populations, and seed persistence has been linked to the secondary seed dormancy potential of a genotype. Temperature influences secondary seed dormancy induction in this species. In these experiments we (1) investigated the influence of temperature and osmotic potential on secondary seed dormancy induction in canola, (2) related these to seedbank dynamics and seedling recruitment of two canola genotypes with different seed dormancy potentials in the field, and (3) investigated the influence of residue, burial depth, and soil type on seedbank dynamics and seedling recruitment in the field. In the laboratory, rates of seed dormancy induction were positively correlated to increasing temperatures and water stress. The role of temperature was approximately threefold more important to seed dormancy development than was osmotic potential within the tested ranges of these variables. In the field, seasonal seedbank dynamics of canola buried at 10 cm were strongly influenced by a genotype's inherent potential for secondary dormancy. An increase in the ungerminable portion of the seedbank was observed in the high-dormancy genotype as soil temperatures increased during spring. This did not occur in the low-dormancy genotype, resulting in sixfold less seed persistence in this genotype by midsummer, by which time, the total remaining seedbank was ungerminable in both genotypes. At the 1-cm burial depth, most of the seedbank was depleted by midsummer of the year after seedbank establishment because of high seedbank mortality in all treatments. Thus, the seasonal recruitment behavior in canola was primarily a function of seed death in the shallow seedbank and a shift to an ungerminable state in the deep seedbank.

Information

Type
Weed Biology and Ecology
Copyright
Copyright © Weed Science Society of America 

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