Quantitative analysis of emergence of seedlings from buried weed seeds with increasing soil depth

Abstract

Trials were carried out to investigate the effects of seed burial depth on seedling emergence rate of 20 weed species. Marked depth-mediated variation in emergence ability of the different species was observed, together with a general pattern of decreasing emergence with increasing soil depth. At 10 cm, only johnsongrass, velvetleaf, catchweed bedstraw, and cutleaf geranium emerged, albeit only in limited numbers. Species most severely inhibited by burial depth were buckhorn plantain, large crabgrass, common purslane, chickweed, and corn spurry, none of which emerged from beyond 6 cm. In all species, depth-mediated inhibition was found to be sigmoidal (polynomial regression). In addition, the number of seedlings and rate of seedling emergence decreased when depth of burial increased. The depth at which the number of emerged seedlings was halved varied by species and ranged from 3.6 cm for common purslane and chickweed to 7 cm for velvetleaf and catchweed bedstraw. Excessive burial depth generally induced dormancy (in roughly 85% of cases) rather than suicide germination. A close inverse relation (second-degree equation) between seed unit weight and depth-mediated inhibition was observed. The physiological involvement of depth inhibition in seed bank ecology is discussed.

Emergence dynamics of barnyardgrass and jimsonweed from two depths when switching from conventional to reduced and no-till conditions

“…Previous trials under laboratory conditions in a siltloam soil (23% sand, 52% silt, 25% clay) have shown no emergence of barnyardgrass from 10 cm depth without disturbance (Benvenuti et al, 2001), which is not in agreement with the current study. However, this disparity could be explained by differences in soil type, environmental conditions (i.e.…”

“…Previous research on barnyardgrass and jimsonweed determined that fatal germination (i.e. the seed germinates, but the seedling dies before reaching the soil surface; Davis & Renner, 2007) of these weeds was approximately 25% and 17%, respectively, from a depth of 12 cm in a siltloam textured soil (Benvenuti et al, 2001). In fact, Gardarin et al (2010) reported that the % of fatal germination is proportional to the soil structure (i.e.…”

Impacts of Organic Zero Tillage Systems on Crops, Weeds, and Soil Quality

“…Results from these studies generally demonstrated that conservation tillage is associated with increased weed pressure [39,52,53]. The enhancement in weed pressure primarily results because inversion tillage tends to distribute weed seeds to a depth from which emergence is unlikely, while non-inversion tillage leaves many weed seeds in the upper soil horizon which enhances the likelihood of emergence [10,53,66]. However, research results have been somewhat variable because of differences in crop management (e.g., crop selection).…”

Plant Succession on Gopher Mounds in Western Cascade Meadows: Consequences for Species Diversity and Heterogeneity

“…It is possible that the seed bank contributes minimally to plant establishment because the soils that comprise mounds are from depths below which most viable seeds are found. Moreover, burial of seeds beneath mounds may actually reduce the potential for emergence from the seed bank (e.g., Benvenuti et al, 2001). …”