Review: Microsite characteristics influencing weed seedling recruitment and implications for recruitment modeling

Abstract

Review: Microsite characteristics influencing weed seedling recruitment and implications for recruitment modeling. Can. J. Plant Sci. 92: 627Á650. A weed seedling recruitment microsite is the location of a weed seed in the soil profile which affects germination, time of emergence and seedling establishment. The relationship between the recruitment of seedlings and their physical environment, including microclimate, soil, topography, and residue cover can provide the key to understanding the timing of seedling recruitment. The variability that exists in germination and establishment requirements within and among weed species raises important questions for recruitment research addressing multiple species, as well as regional models of genetic variability within species. Current weed recruitment research focuses mainly on summer annual species in annual cropping systems. However, with changes in cropping systems, climate, and weed biology, there will be an increasing demand for the management of both summer and winter annual weeds that develop very early in the spring. Many studies to date take an average of microsite conditions, particularly for soil depth, to describe the seedling recruitment zone. Whereas this practice of under-sampling expedites lengthy and difficult soil environmental measurements, it limits the description of the microsite for predictive purposes. Because soil disturbance disperses seeds to microsites throughout the vertical profile of the shallow seedling recruitment zone, seeds are subjected to gradients of temperature and water that create diverse microsites with depth in the recruitment zone. Research on the interactions of microclimate, field topography, soil properties and agronomic practices can further our knowledge base of the seedling recruitment microsite to better understand weed ecology and population dynamics generally, as well as enhance our ability to predict seedling recruitment specifically.Bullied, W. J., Van Acker, R. C. et Bullock, P. R. 2012. Parame`tres des microsites qui influent le recrutement des plantules de mauvaises herbes et implications pour la mode´lisation du recrutement. Can. J. Plant Sci. 92: 627Á650. Par microsite de recrutement des plantules de mauvaises herbes, on entend l'endroit ou`la graine de mauvaise herbe se trouve dans le profil de sol. Cet emplacement affecte la germination, le moment de la leve´e et l'e´tablissement de la plantule. Les liens entre le recrutement des plantules et le lieu physique de ces dernie`res, notamment le microclimat, le sol, la topographie et la couverture de re´sidus pourraient nous aider a`comprendre quand il y a recrutement. La variabilite´des contraintes associe´es a`la germination et a`l'e´tablissement des plantules qu'on observe au sein d'une espe`ce et entre les espe`ces de mauvaises herbes soule`ve d'importantes questions pour la recherche sur le recrutement qui porte sur de nombreuses espe`ces d'adventices ainsi que pour les mode`les re´gionaux illustrant la variabilite´ge´ne´tique d'une espe`ce. La recherche actuel...

Vicia villosa ssp. villosa Roth field emergence model in a semiarid agroecosystem

“…In agreement with Bullied, van Acker, et al. (), the minimum threshold temperature for hypocotyl elongation was higher than the base germination temperature (5 and 2°C respectively).…”

“…The minimum threshold water potential at which germination ceases in many agricultural species ranges from −0.1 to −1.5 MPa (Bullied, Bullock, et al., ). Despite many species being capable of germinating at very low water potentials (i.e., Secale cereale, Brassica rapa, Cicer arietinum ), the rate and uniformity of germination and pre‐emergence growth is often compromised by suboptimal soil water potentials (Bullied, van Acker, et al., ; Oryokot, Murphy, Thomas, & Swanton, ; Tribouillois et al., ). As observed in this study, although hairy vetch is able to germinate at relatively low soil water potentials (ψ b(50) = −1.06 MPa), the rate of hypocotyl elongation would be ≈0.8 mm/day.…”

“…When hairy vetch becomes a problematic weed, the timing of seedling emergence relative to the crop is important in planning and optimizing the time of control (Bullied, Bullock, & van Acker, ; Bullied, van Acker, & Bullock, ). Many mechanistic models based on the description of the biophysical processes have been proposed for other weed species (Colbach, Dürr, Roger‐Estrade, & Caneill, ; Gardarin, Durr, & Colbach, ; Vleeshouwers & Kropff, ).…”

Inhibiting effect of shallow seed burial on grass weed emergence

“…For example, seed size determines the maximum depth from which seedlings can emerge (Benvenuti et al 2001;Chauhan et al 2006;Gardarin et al 2010). Moreover, germination of grass species, which usually require fluctuating temperatures or light for dormancy break, could be reduced if deeply buried in the soil (Bullied et al 2012;Batlla & BenechArnold 2014). 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).…”

“…Moreover, germination of grass species, which usually require fluctuating temperatures or light for dormancy break, could be reduced if deeply buried in the soil (Bullied et al 2012;Batlla & BenechArnold 2014). 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).…”