Phalaris minor seedbank studies: longevity, seedling emergence and seed production as affected by tillage regime

Abstract

Studies were conducted to investigate seed longevity, seedling emergence and seed production of the weed Phalaris minor in wheat in northern India. The longevity of P. minor seeds buried in bags in the field was often limited to less than 1 year, although many seeds buried at 30 cm depth in a rice-wheat rotation remained viable for longer. The application of direct seeding in wheat reduced the seedling emergence rate of P. minor, when compared with conventional ploughing and sowing. However, a larger P. minor seedbank in the upper soil layer in plots under direct seeding partly reversed this positive effect in one of the two studies. Besides differences in relative distribution of weed seeds through the soil profile, it was likely that other factors such as reduced soil disturbance and soil characteristics associated with the application of direct seeding were also involved in regulating the emergence rate. Mature P. minor plants in wheat were found to invest a stable part (27%) of their aboveground biomass in seed, so that total seed weight was strongly linearly correlated with the aboveground biomass of the mother plant. Individual seed weight, however, was little affected by the weight of the mother plant.

Effect of herbicide resistance on seed physiology of Phalaris minor (littleseed canarygrass)

“…Under natural conditions, the seeds reach their highest germination percentage at 70 days after dispersal (Om et al, 2005). However, excess of soil humidity decreases their vigor and longevity, depending on their depth in the soil (Franke et al, 2007).…”

Organic Agriculture and the Quest for the Holy Grail in Water-Limited Ecosystems: Managing Weeds and Reducing Tillage Intensity

“…Additionally, when tillage intensity is reduced, more weed seeds remain on the soil surface and within the first few centimeters of the soil [46], making them more susceptible to seed predators [47,48] and seedling desiccation [49]. While the exact changes to the seedbank associated with tillage reduction in organic settings may be highly variable and difficult to quantify [38], results suggest that weed seedlings that emerge within no-till and reduced-tillage soils encounter greater resistance, and emerge at lower rates from the top layer of the soil profile [50], compared to tilled soils that allow deeper emergence [51]. Furthermore, weed seeds that germinate on the soil surface often experience fatal germination because the radicle may have difficulty penetrating the soil surface in a timely manner [38].…”

Impact of Tillage Intensity, NPK Fertilization and Weed Control on Seed Yield and Yield Components of Flaxin Newly ReclaimedLands

“…Mankowski et al (2013) reported that no-tillage reduced the number and weight of weeds compared to conventional cultivation with plowing. That could be explained by accumulation of seeds near the soil surface in no-tillage system, thus seeds are exposed to higher mortality risks through weather variability and predation (Blubaugh & Kaplan, 2015) and less seedling establishment (Franke et al, 2007).…”