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Some Aspects of the Reproductive Biology of Limonium vulgare Mill., and Limonium humile Mill.
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1968
Year
EngineeringFertilityBotanyGeneticsReproductive BiologyLower GerminationReproductive BiotechnologyReproductive PhysiologySeagrassSubsequent GerminationPlant ReproductionInfertilityOsmotic StressHigher GerminationBiologyLimonium Vulgare Mill.Seed GerminationLimonium Humile MillMarine BiologyMedicinePlant Physiology
The germination of two species of salt-marsh plants Limonium vulgare Mill., and L. humile Mill., is investigated in relation to their ecology. Germination is inhibited by sea water, but germination even in fresh water is low. Inhibition of germination by sea water is negatively correlated with water uptake. However, a treatment in sea water stimulates subsequent germination in fresh water. The effect of the sea-water treatment appears to be one of osmotic shock which weakens the seed coat. Variation in response to the treatment is partly genetical and partly environmental. Seeds in different parts of the salt-marsh will be subject to differing conditions, both during seed development and during the interval between seed maturation and seed dispersal. In connection with this the effect of leaching by sea water and fresh water is considered. The response to a sea-water treatment varies with time. Considered in the long term it shows some cyclical variation which might correspond with the tidal cycle. It is shown that seeds of Limonium can survive long periods in sea water. There is a slow rate of germination during immersion. Most of those seeds which do not germinate in sea water survive to germinate rapidly in fresh water. The response to oxygen concentration, light, and temperature is also investigated. Experiments on seedling growth and establishment show the need for fresh water and a suitable substrate. Mud gives a lower germination but a higher survival, while sand gives a higher germination but a lower survival. The dispersal of Limonium seeds in nature is investigated. Seeds of Limonium are most abundant in the drift line, but even these only represent a small fraction of the total produced. It is considered that reproduction by seed is only important when a new area is being invaded. Subsequent reproduction is largely by vegetative spread. The ecological implications of the germination experiments are discussed.