Evaluation of growth and gas exchange response of acacia ehrenbergiana hayne seedlings to variations in seed mass

The effect of seed mass of Acacia ehrenbergiana Hayne on seedling growth and gas exchange activity under glass house conditions was investigated. Seeds were collected from three locations (Al Madinah (24 degree 89 minutes N, 39 degree 16 minutes E), Aseer (17 degree 55 minutes N, 42 degree 11 minutes E) and Baha (19 degree 13 minutes N, 41 degree 80 minutes E) in Saudi Arabia. The seeds were categorized into large, medium and small on the basis of the seed mass. Seeds were sown in potted soil (sand, clay and peat moss, 2:2:1 v/v) for six months. Seedling growth parameters and gas exchange were measured. Seedlings emerged from large seeds exhibited significantly faster growth in terms of shoot and root length and more dry weight, higher RGR (relative growth rate) and greater net photosynthetic and transpiration rates and stomatal conductance than those emerged from medium and small seeds. Leaf number also increased with seed mass but inconsistently. (author)