Influence of Soil Temperature and Soil Moisture on Green Foxtail (Setaria viridis) Establishment in Wheat (Triticum aestivum)

Abstract

The rate and final germination percentage and emergence of green foxtail [Setaria viridis(L.) Beauv.] was found to be very dependent on the soil temperature and moisture conditions at the time of seeding. In contrast, the germination and emergence of wheat (Triticum aestivumL. ‘Sinton’) was only slightly affected over the temperature and moisture range of the study. In laboratory studies, a temperature decrease from 20 to 15 C caused a 53- and 12-h delay in the time to reach 50% germination of green foxtail and wheat, respectively. Soil moisture was found to have a greater effect than soil temperature on green foxtail germination. At −5.3 bars water potential, the final germination percentage of green foxtail was less than at the higher water potentials. A further decrease in the water potential to −6.5 bars effectively reduced green foxtail germination to zero. Wheat germination was delayed only slightly, and the final germination percentage remained unchanged over the range of 0 to −15.3 bars water potential. In field studies, a soil temperature decrease from 22 to 14 C caused a 6-day delay in the time of 50% emergence of green foxtail, and the emergence of wheat was delayed only 1 day by a similar decrease in temperature. Field studies showed that when the soil was moist (0 to −4 bars) and soil temperatures were warm (20 to 25 C), green foxtail emerged within a few days of wheat. However, when the soil was dry (-4.0 to −6.5 bars) and soil temperatures were low (15 to 20 C), green foxtail emerged 7 to 14 days after wheat. The intensity of green foxtail competition was greater when green foxtail emerged within a few days of wheat than when green foxtail emerged 2 weeks after wheat.