Germination Patterns of Dimorphic Achenes in Launaea nudicaulis (Asteraceae) Growing in Desert Environments
Launaea nudicaulis (Asteraceae) produces two morphologically distinct types of achenes (whitish brown and black) in a single capitulum. All L. nudicaulis achenes have a pappus and pappi were removed artificially in this study for experimental purposes. The germination of achenes of both colours, with and without pappi, under various temperature regimes and illumination conditions was tested. Different coloured achenes showed differences in their mass and germination behavior. Whitish brown achenes (with and without pappi) displayed...
[Seed colour affects light and temperature requirements during germination in two Lotus species (Fabaceae) of the Arabian subtropical deserts, El color de la semilla afecta los requerimientos de luz y temperatura durante la germinación en dos especies de Lotus (Fabaceae) de los desiertos subtropicales Árabes]
Heterogeneity in seeds mostly occurs due to physiological, environmental and genetic factors, and these could affect seed dormancy and germination. Therefore, the aim of our study was to assess the effect of seed colour on germination behavior. For this, both light and temperature requirements were assessed in Lotus glinoides and Lotus halophilus (Fabaceae) from the hyper-arid deserts of the United Arab Emirates. Germination was assessed in terms of both final germination level (percentage) and germination...
Seed mucilage effect on water uptake and germination in five species from the hyper-arid Arabian desert
The effect of mucilage removal on germination percentages and velocity (Timson's index) was studied for five Arabian desert species (Lavandula subnuda, Lepidium aucheri, Boerhavia elegans, Plantago ciliata and Plantago amplexicaulis) under two photoperiods (0, 12 h of light daily) and three thermoperiods (night/day temperatures of 15/25, 20/30 and 25/35 °C). Mucilage presence increased water uptake in all species, and was associated with higher germination percentages in L. subnuda, B. elegans and P. ciliata, but not L. aucheri and P. amplexicaulis. Germination velocity response to mucilage presence was mixed, being increased in L. aucheri and reduced in L. subnuda. In all species germination was increased by light and affected...
Maternal habitat affects germination requirements of Anabasis setifera, a succulent shrub of the Arabian deserts
The effects of maternal habitat on light and temperature requirements during germination were assessed for the succulent desert shrub Anabasis setifera. Seeds were collected from the Mediterranean habitats of Egypt and the hyper-arid subtropical habitats of the United Arab Emirates (UAE). Seeds from the two populations were germinated in three temperature treatments in both a light/dark regime and continuous darkness. Seeds from the Egyptian population germinated significantly greater and faster than those of UAE. Seeds...