The effect of light intensity on seed production and quality in a number of Australian wild oat (Avena fatua L.) lines

Several aspects of the maternal environment (e.g. air temperature, soil moisture, soilnutritional status and photoperiod) are known to influence seed production and qualityin a range of plant species. However, little is known about the effect of other environmentalfactors, such as the light intensity perceived by the developing plant, on theseseed characters. This is particularly important when elucidating the persistence mechanismsof annual weeds that may produce seeds under a crop canopy. Therefore, the aimof the present study was to determine the effect of light intensity on the reproductivecharacteristics of a number of wild oat (Avena fatua L.) lines originating from a range oflocations in Australia. Under a reduced light intensity and in the absence of competition, the overall plant growth, seed production, seed weight and depth of seed dormancy (butnot seed viability) were all reduced compared with that seen in plants growing in fullsunlight. In addition, the reduced light intensity conditions significantly increased plantheight and reduced tiller production, but did not affect leaf area production. In general, these responses were the same for all six lines studied and indicate that the reduced lightintensity perceived by late germinating weeds present within a crop canopy causes theproduction of seeds with traits that are likely to result in rapid loss from the soil seedbank. In addition, all lines grown under the reduced light intensity conditions had anextended development time (up to 70 days), that it would be unlikely that they wouldreach maturity before the crop was harvested, and therefore would not be able to returnany seed to the soil seed bank