Laboratory Studies of Germination and Growth in Plant Species Associated with an Elevation Gradient in South West Saudi Arabia PDF

Keywords

Seeds, Saudi arabia, temperature

Abstract

Germination response of seeds of 15 wild species were tested on a temperature gradient. Growth rates of seedlings were evaluated at the optimum temperature for germination for each species. These species include 14 perennials and one annual found at various elevations between 20 and 2700 meters above sea level in the following order: Cassia italica, Salvadora persica, Calotropis procera, Datura innoxia (annual), Moringa peregrina, Lawsonia innermis, Abutilon pannosum, Acacia tortilis, Acacia ehrenbergiana, Acacia asak, Cucumis prophetarum, Coccinia grandis, Nepeta deflersiana, Verbascum nubicum, and Jasminum grandiflorum. Seeds of most plants found at low elevation germinate best within a relatively narrow range of temperature at the warm end of the temperature gradient. Seeds collected from intermediate elevation show broader response to temperature and germinate at moderate temperature. Seeds collected from high elevation germinate best at low temperature. A relatively higher root/shoot ratio was recorded among plants of high elevation. Plants at different positions along the gradient showed different attributes indicating strategies for survival under the rather harsh and unpredictable environments at low and high altitudes. Among such attributes are rapid germination, germination under a broad range of temperature, germination in darkness, and high rate of root elongation.