Seed longevity and dormancy of four summer annual grass weeds in turf

Abstract

Digitaria sanguinalis, Eleusine indica, Setaria glauca and S. viridis are troublesome summer annual weeds in turf. For taking rational decisions on the necessity for the level and type of weed management, it is important to know when weeds are ready to emerge (dormancy status) and also how long weed seeds can survive in the soil. Seeds of these four species were buried 4.0-4.5 cm deep in steel mesh net bags placed under permanent turf and periodically exhumed for 3 years to evaluate viability and determine the dormancy/non-dormancy cycle. D. sanguinalis, S. glauca and S. viridis showed the typical dormancy cycle of summer annual species, and their seed viability declined completely after 3 years of burial. In contrast, E. indica demonstrated unusual behaviour, with long persistence and no dormancy.

Inhibiting effect of shallow seed burial on grass weed emergence

“…The temporal dynamics of s. viridis emergence observed during the present experiment confirmed the results by Masin et al (2006) who similarly described a very high germinability for this species in the first spring after burial, while seed viability declined to 60% of the initial after one year of burial. It may be supposed that also in the present study most buried s. viridis seeds were released from dormancy after the first winter of burial and germinated, consequently a high seedling emergence was observed from the superficial burial depths during YAS 1.…”

“…Masin et al (2006) described high germinability for this species after the first winter burial, similar to that of green foxtail, but the smaller seed size and seed stored reserves, and the limited shoot diameter and length of this species (Gardarin et al 2010) probably penalised D. sanguinalis emergence from depths below 5 cm. Superficial soil tillage could therefore be an effective control tool for D. sanguinalis in conservation agriculture systems since seedbank of this species is normally subjected to fast depletion if seed rain is avoided because seed viability dramatically decreases after two years of burial (Masin et al 2006). However, D. sanguinalis seeds usually exit dormancy and germinate progressively later than many other grass weeds, hence emergence flushes of this species can extend to summer months (Masin et al 2006).…”

“…Since non-germinated seeds were not recovered from the soil at the end of this study, it was not possible to measure the percentage of seed decay, fatal germination, and dormant seeds after the two years of burial. Dormant seeds proved to be the main cause of reduced emergence for D. sanguinalis and s. halepense for short term experiments (Benvenuti et al 2001), while the incidence of seed decay and fatal germination was reported to increase during prolonged seed burial reducing for example seed viability of s. viridis and D. sanguinalis to less than 1% of original seed number after 3 years of burial (Masin et al 2006). However, some interesting indications and conclusions on the efficacy of superficial soil tillage as weed control tool for the studied species can be drawn by analysing their different behaviour.…”

“…The amplitude of daily temperature fluctuation is indeed maximum on the soil surface and rapidly diminishes with depth (Bullied et al 2012;Loddo et al 2015) and light usually only penetrates the first mm of the soil (Benvenuti & Macchia 1998). The various grass weed species can represent different seed bank persistence, however their seeds tend to largely germinate in the first years after dissemination and are usually characterized by reduced longevity in soil (Masin et al 2006). Information on the emergence response of grass species from different burial depths could help evaluate the efficacy of superficial soil tillage as weed control tool in the conservation agriculture systems.…”

Simulation of control strategies for decision-making regarding Digitaria sanguinalis in glyphosate-resistant soybeans

“…The seeds of this weed follow the typical dormancy pattern exhibited by most summer weeds in temperate climates. First, a period of deep dormancy occurs after dispersion in autumn (Gallart et al, 2008), then it is broken by cold temperatures during the winter (Toole and Toole, 1941;Delouche, 1956) and finally warm spring temperatures trigger germination and emergence (Masin et al, 2006). A high percentage of germination is generally achieved by alternating temperatures (20°/30 °C, 20°/35 °C, 20°/40 °C (18 h/6 h)) (Toole and Toole, 1941) or constant warm temperatures (25 °C, 30 ºC) (King and Oliver, 1994).…”