Growth responses to elevated temperature and reduced soil moisture during early establishment of three annual weeds in four soil types

Abstract

We investigated the effects of simulated prospective increased temperatures and reduced soil moisture during the vegetation period on the early growth of three weed species that co-occur in spring crops and are currently spreading in Europe. Potted four-species crop-weed-communities of Abutilon theophrasti, Datura stramonium, Iva xanthiifolia, and maize were exposed to warming (ambient temperature + 2.5 degrees C, treatment "warm") and drought (soil water potential of -0.1 to -1.5 MPa, "dry") versus ambient temperature (treatment "ambient") and a soil water potential of -0.0036 MPa ("moist"), in four soil types (clay, loess, peat, sand based mixtures) in greenhouse settings. We determined the performance of the weeds in terms of total biomass accumulation as well as their morphological acclimation regarding root length, leaf size and root-to-shoot ratio at various combinations of the experimental factors. Warm-dry conditions had a significant negative effect on total weed biomass and also resulted in a higher proportion of maize in total aboveground biomass. In D. stramonium, aboveground vs. belowground allocation and leaf size responded more strongly to the experimental factors than in the other two species. Total biomass values of individual plants in warm-dry conditions on average were > 50%, 40 to 55%, and < 40% of those in ambient-moist conditions for A. theophrasti, I. xanthiifolia, and D. stramonium, respectively. Soil and its interaction with moisture and temperature additionally had a significant effect on various traits of the weed species which highlights the importance of considering this factor when investigating plant responses to altered climate conditions.