Germination ecology of hairy fleabane (Conyza bonariensis) and its implications for weed management

Abstract

Hairy fleabane [Conyza bonariensis (L.) Cronquist] is a problematic weed in Australian no-till cropping systems. Consequently, a study was conducted to examine the effect of temperature, light, salt stress, osmotic stress, burial depth, and sorghum crop residue on germination and emergence in two populations (C and W: collected from chick pea [Cicer arietinum L.] and wheat [Triticum aestivum L.] fields, respectively) of C. bonariensis. Both populations were able to germinate over a wide range of alternating day/night temperatures (15/5 to 35/25 C); however, the C population had optimum (and similar) germination over the range of 20/10 and 30/20 C, while the W population showed maximum germination at 25/15 C. A negative relationship was observed between osmotic potential and germination, with 31% and 14% germination of the C and W populations at −0.6 MPa, respectively. These observations suggest that population C was more tolerant to higher osmotic potentials than population W. Seeds of both populations germinated when exposed to a wide range of sodium chloride levels (NaCl, 0 to 200 mM); however, beyond 200 mM NaCl, no germination was observed in either population. Maximum germination of the C (70%) and W (41%) populations was observed on the soil surface with no emergence from a burial depth of 1 cm. The application of sorghum residue at an amount of 6,000 kg ha−1 reduced emergence of the C and W populations by 55% and 58%, respectively, compared with the no-residue treatment. Knowledge gained from this study suggests that the following strategies could be used for more efficacious management of C. bonariensis: (1) a shallow-tillage operation to bury weed seeds in conventional tillage systems, and (2) retention of sorghum residue on the soil surface in no-till systems.

Seed germination ecology of Conyza sumatrensis populations stemming from different habitats and implications for management

“…Several enzymes necessary for seed germination are regulated by temperature; thus, it is an important environmental cue influencing seed germination of weeds and crop plants [ 31 ]. Conyza species successfully germanite under a temperature range of 20 and 30°C, and 20°C is regarded optimum for their seed germination [ 23 , 26 – 28 , 32 , 33 ]. Nonetheless, some studies have reported that several Conyza species are capable of germinating at higher temperatures [ 24 , 26 , 32 ].…”

“…Conyza species successfully germanite under a temperature range of 20 and 30°C, and 20°C is regarded optimum for their seed germination [ 23 , 26 – 28 , 32 , 33 ]. Nonetheless, some studies have reported that several Conyza species are capable of germinating at higher temperatures [ 24 , 26 , 32 ]. Due to the reason, inferring seed germination of each species under various environmental cues is necessary for their successful management.…”

“…Conyza seeds require definite light period for their seed germination; thus, emerge from the upper soil layers [ 26 , 30 ]. Absence of seed dormancy in Conyza species is a big hurdle in their longevity in the soil seed bank [ 28 ].…”

Differential germination characteristics of glyphosate-resistant and glyphosate-susceptible Chloris virgata populations under different temperature and moisture stress regimes

“…This type of the ‘weed shift’ behavior has previously been observed in many weed species such as Sonchus oleraceus L. [ 26 ], Sisymbrium thellungii O. E. Schulz. [ 27 ] and Conyza bonariensis L. [ 28 ]. However, it should not be implied that successful germination at low temperatures in laboratory conditions means successful survival in field conditions, as frost may kill weed species in winter.…”

Germination biology of three populations of Navua sedge (Cyperus aromaticus)

“…The germination biology of various populations of weed species is known to vary under different environmental conditions (Chadha et al 2019;Loura et al 2020). Within the infestation region in Queensland, Australia, variable environmental conditions occur for rainfall and temperatures, and therefore weed populations may differ in their responses to these different environments and may require different management practices (Cai et al 2005;Iqbal et al 2019;Whitfield and Queensland Department of Environment and Resource Management 2010).…”