Influence of seed dimorphism and provenance on seed morphology, dispersal, germination and seedling growth of Brachyscome ciliaris (Asteraceae)

Abstract

Abstract. Brachyscome ciliaris is a floriferous Australian native daisy, with potential for use as a horticultural species. The species is hardy and seeds are relatively easy to germinate, but it is unique within the Brachyscome genus in that seeds are distinctly dimorphic. Within a fruiting capitulum, ray seeds are smooth and narrow with a minute pappus, whereas disc seeds have broad flat wings with curled hairs and a longer pappus than that of ray seeds. Both seed morphs, collected from five populations of the species, were tested to determine differences in their morphology, germination speed and percentage, seedling growth and wind-dispersal characteristics. Ray seeds were generally lighter and smaller than disc seeds and their length varied significantly with provenance. Dormancy levels of the two seed morphs and growth of rayand disc-derived seedlings did not differ significantly, but differences were significant among the five populations tested. Seeds germinated readily, and germination was optimal under winter or summer conditions and lower in spring or autumn. Seed production by plants raised from ray or disc seeds was identical, but Noora-sourced plants yielded more seed than did plants sourced from the other provenances tested. Seed size, germination and plant growth of B. ciliaris varied significantly among populations. Winged disc seeds were dispersed slightly further by wind than were wingless ray seeds. We concluded that dormancy, germination and seed-yield characteristics of B. ciliaris were all influenced more by seed provenance than by seed morph (ray or disc).

The influence of ethanol as a solvent on the gibberellic acid-induced germination of Brachyscome and Allittia (Asteraceae) seeds

“…The experiment was replicated four times, with each dish being equivalent to a single experimental unit. Dishes were incubated under spring/autumn conditions (12 h day -1 photoperiod, 22 ○ C/10 ○ C (±1 ○ C) day/night temperature), representing South Australian climatic conditions under which seeds were likely to germinate (Aleman et al 2015). Lighting was provided by GE Polylux XL F36W/840 fluorescent tubes delivering a photosynthetic photon flux density of 50 µmol m -2 s -1 .…”

The environmental adaptation strategy of seed germination, and roles of the seed pappus on dispersal and hypocotyl hairs on seedling anchorage inTamarix ramosissima

“…2013 ). In Brachyscome ciliaris , there are two types of seeds: ray seeds, which are smooth and narrow with a minute pappus, and disc seeds, which have a pappus, wing, and curly hairs; disc seeds can disperse a greater distance by wind than ray seeds ( Aleman et al 2015 ). Centaurea solstitialis seeds display a task-allocation strategy, wherein large numbers of pappus seeds are produced, which enhances the competitiveness of seedlings through rapid dispersal and seedling establishment; by contrast, non-pappus seeds delay germination and remain dormant, thus ensuring reproduction in changing environments ( Florencia Miguel et al .…”