Effect of water stress on weed germination,growth characteristics, and seed production:a global meta-analysis

Authors: SINGH, MANDEEP - University Of Nebraska; THAPA, RESHAM - North Carolina State University; KUKAL, MEETPAL - Pennsylvania State University; Mirsky, Steven; JHALA, AMIT - University Of Nebraska

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/11/2022
Publication Date: 10/21/2022
Citation: Singh, M., Thapa, R., Kukal, M.S., Mirsky, S.B., Jhala, A.J. 2022. Effect of water stress on weed germination,growth characteristics, and seed production:a global meta-analysis. Weed Science. https://doi.org/10.1017/wsc.2022.59.
DOI: https://doi.org/10.1017/wsc.2022.59

Interpretive Summary: Weeds compete for water with crops among other resources and the competition increases under water-limited environments. We performed a quantitative review of the existing evidence base to understand how water stress effects germination, above- and below-ground growth characteristics, and seed production of weeds. Overall, our results indicate that: 1) water stress significantly reduced all indices related to weed germination/emergence, growth (seedling radical/root length, plant height, leaf area, leaves per plant, total biomass, root biomass, and shoot biomass), and seed production (inflorescences and seeds per plant) with the exception of root:shoot ratio, and 2) water stress effects intensified as moisture becomes more deficit or water stress intensity increased. Weeds will adjust their growth morphology to cope up with the water stress and will continue to germinate, survive, grow, flower, and produce seeds even under severe drought or water stressed conditions. This research will be useful for researchers and agricultural professionals to determine weeds' relative adaptability and its infestation in water-limited environments and hence formulate multi-tactic integrated weed management strategies for farmers.

Technical Abstract: Weeds compete with crops for soil moisture, along with other resources, which can impact the germination, growth, and seed production of weeds; however, this impact has not been systematically recorded and synthesized across diverse studies. To address this knowledge gap, a global meta-analysis was conducted using 1,196 paired observations from 86 published articles assessing the effect of water stress on weed germination, growth characteristics, and seed production. These studies were conducted and published during 1970 through 2020 across four continents (Asia, Australia, Europe, and North America). Imposed water stress was expressed as solution osmotic potential (solution), soil water potential (soil), or soil moisture as percent field capacity. Meta-analysis revealed that water stress inhibits weed germination, growth, and seed production, and the quantitative response intensified with increasing water stress. A solution greater than -0.8 MPa completely inhibits germination of both grass and broadleaf weeds. A solution from -0.09 to -0.32 MPa reduces weed germination by 50% compared with the unstressed condition. Moderate soil water stress, equivalent to 30% to 60% field capacity, inhibits growth characteristics (branches or tillers per plant, leaf area, leaves per plant, plant height, root, and shoot biomass) by 33% and weed seed production by 50%. Severe soil water stress, below 30% field capacity, inhibits weed growth by 51% and seed production by 88%. Although water stress inhibits weed growth, it does not entirely suppress the ability to germinate, grow, and produce seeds, resulting in weed seedbank accumulation. This creates management challenges for producers, because weed seeds can survive in the soil for many years, depending on weed species and environmental conditions. Quantitative information compiled in this meta-analysis can be instrumental to model the weeds’ multidimensional responses to water stress and designing integrated weed management strategies for reducing the weed seedbank.