Germination and growth requirements of Rogeria longiflora - Medicinal plant of the Namib Desert

Rogeria longiflora (Royan). Gray ex DC. (Pedaliaceae) is a medicinal plant used only by rural local people and not much information is available on its propagation practices. The present study highlights the effect of temperature, nutrients, smoke-water, smoke-isolated butenolide (known as karrikinolide, KAR(1)) and watering frequency on seed germination and post-germination growth of R. longiflora. Alternating temperatures (30/15 degrees C) with 16 h photoperiod yielded the highest percentage germination. The seeds exhibited maximum germination at pH 4 compared to the other tested buffer solutions. Germination was not affected by smoke treatments, as fire is uncommon in deserts. However, vigour of the seedling was significantly improved with KAR(1) treatment (10(-8) M). Deficiency of nitrogen (N) suppressed seed germination, shoot length and root length of 21-day-old seedlings. Seed germination was the highest in the absence of phosphorus (P). Watering thrice weekly showed better shoot length, root length and plant weight after 12 weeks compared to watering once and twice weekly. The findings of this study reveal that N, P and moist conditions are essential for optimum growth of R. longiflora plants. (C) 2011 SAAB. Published by Elsevier B.V. All rights reserved.