Premium
Weedy adaptation in Setaria spp. V. Effects of gaseous environment on giant foxtail ( Setaria faberii ) (Poaceae) seed germination
Author(s) -
Dekker Jack,
Hargrove Mark
Publication year - 2002
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.89.3.410
Subject(s) - germination , setaria , foxtail , radicle , biology , setaria viridis , poaceae , oxygen , respiration , carbon dioxide , agronomy , botany , chemistry , ecology , organic chemistry , weed
The effects that naturally occurring gases (oxygen, nitrogen, carbon monoxide) may cause in dormant giant foxtail ( Setaria faberii ) seed germination under favorable temperature and moisture conditions were investigated. The germination responses to gas mixtures supported the hypothesis that S. faberii germination behavior is regulated by the amount of oxygen taken into hydrated seed over time. Setaria faberii seed germination was markedly affected by O 2 concentration (in N 2 ) above and below that of air (20% O 2 ): the largest increase in germination (from 37 to 60%) occurred between 20–25% O 2 ; between 0–10% O 2 , germination increased from 0–30%; and surprisingly germination at 10 and 20% O 2 was similar. These observations reveal an asymmetrical response to incremental changes in O 2 above and below that typically found in agricultural soils. Carbon monoxide had opposite effects on S. faberii germination in air depending on concentration, stimulation, and inhibition: germination increased from 37 to 56% with the addition of 1% CO, but decreased from 37 to 14% with 75% added CO. An explanation may be that there are two separate effects of CO, each occurring in different physiological systems of dormant seeds at the same time. At high concentrations (75%) in air CO inhibited seed germination, probably by inhibiting mitochondrial respiration. But low CO concentrations (0.1 or 1%) in air stimulated seed germination. It was not apparent which physiological system(s) CO and O 2 affected. It seems unlikely that CO‐stimulated germination arises from effects on the respiratory apparatus, but may be a consequence of CO interactions with an as yet unknown physiological factor in the seed. We provide a model of Setaria spp. dormancy consistent with its seed morphology, the gas‐germination data, and the hypothesized second physiological factor that may be involved in CO stimulated germination.