Seed colour affects light and temperature requirements during germination in two Lotus species (Fabaceae) of the Arabian subtropical deserts

<p>The effect of seed colour on germination behavior and both light and temperature requirements was assessed in <em>Lotus glinoides </em>and <em>Lotus </em><em>halophilus</em> (Fabaceae) from the hyper-arid deserts of the United Arab Emirates. Germination was assessed in term of both final germination level (percentage) and germination rate, as expressed by Timson’s germination velocity index. <em>Lotus glinoides</em> produces black and yellow-colored seeds and <em>L. halophilus</em> produces green and yellow seeds. Different seed lots were germinated in both light and darkness at different temperatures. Yellow seeds of the two species attained significantly lower germination, compared to black and green seeds. There was no specific light or temperature requirements for the germination of the two coloured seeds of <em>L. glinoides</em>; the effect of interactions between seed colour and both light and temperature of incubation on final germination percentage were not significant. In <em>L. halophilus</em>, green seeds germinated significantly more in both light and darkness at lower temperatures (15/25 °C) and in light at higher temperatures (25/35 °C), compared to yellow seeds. Yellow seeds germinated faster, compared to black at 15/25 °C in <em>L. glinoides </em>and compared to green seeds at15/25 °C and 25/35 °C in <em>L. halophilus</em>. Seed colour variation, at least in <em>L. halophilus</em><em>,</em> could be a survival strategy that would determine the time of germination throughout the year in the unpredictable desert environment.</p>