Planta Daninha (2011) 29, 333-342

O.M. Yamashita and S.C. Guimarães (2011)
Germinação de sementes de Conyza canadensis e Conyza bonariensis em diferentes condições de temperatura e luminosidade
[Germination of Conyza canadensis and Conyza bonariensis seeds under different conditions of temperature and light]
Planta Daninha 29 (2), 333-342
Abstract: Horseweed (Conyza canadensis and C. bonariensis) is a weed of increasing importance in Brazil. These species occur in different regions of the world and are important weeds in perennial and annual crops under no tillage, minimum tillage and horticultural areas. In this work, we studied the effect of constant temperatures on germination of both species, through two germination chamber experiments under constant temperature and 12 hours of light. The experimental unit consisted of acrylic boxes with 50 seeds placed on two leaves of blotting paper moistened with distilled water. In the first experiment, the germination behavior of the species was studied at constant temperatures of 15, 20, 25, 30, 35 and 40 ºC. In the second experiment, the germination behavior of the species under conditions of constant temperatures (20, 25 and 30 ºC) in the absence/presence of light (12 hours). Germination and germination rate were higher at temperatures of 20 and 25 ºC, for both species under study. Germination under temperatures of 15, 35 and 40 ºC was reduced significantly. Both species behave as positive photoblastic.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
(original language: Portuguese)
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Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Erigeron canadensis (weed)
	Erigeron bonariensis (weed)