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Environmental Factors Influencing the Expression of Dormancy Patterns in Weed Seeds
H. J. BOUWMEESTER and C. M. KARSSEN
Annals of Botany
Vol. 63, No. 1 (January 1989), pp. 113-120
Published by: Oxford University Press
Stable URL: http://www.jstor.org/stable/42758158
Page Count: 8
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Buried seeds often show seasonal periodicity of dormancy. Dormancy patterns of Chenopodium album, Polygonum persicaria, Sisymbrium officinale and Spergula arvensis were studied by burying seeds under field conditions in sandy loam in December, 1986. Seeds were exhumed at regular intervals and germination was subsequently tested in the laboratory. It was shown that the conditions of the germination test influenced the expression of the dormancy pattern. Germination of C. album and S. arvensis always depended on the presence of light, whereas seeds of S. officinale completely lost their light dependency during the first winter. Application of nitrate during the germination test in light improved germination of all species. Dark germination was not stimulated by nitrate alone. Desiccation of the exhumed seeds at a r. h. of approx. 15 % enhanced germination under all conditions. A combination of several stimulating factors revealed breaking of dormancy much earlier in the season. During induction of secondary dormancy the effect of the test conditions was even more pronounced. Dormancy induction could be overlooked for several months when seeds were desiccated and/or given nitrate during the germination test in light. It is hypothesized that in the field both desiccation -due to cultivation and dry spells -and nitrate enrichment of the soil will influence the expression of the seasonal pattern of dormancy and therefore enlarge the period of possible seedling emergence.
Annals of Botany © 1989 Oxford University Press