Growth Performance and Biomass Partitioning of the Desert Shrub Calotropis Procera under Water Stress Conditions

Calotropis procera, is a spreading drought resistant desert shrub, grows in semi arid and arid regions in South West Asia and Africa. It has been widely used in the traditional medicine in the tropics of Asia and Africa due of its active medicinal compounds. A pot experiment was carried out to investigate the effects of water stress on growth of C. procera. The treatments include severe water stress, 30% of soil field capacity (FC), moderate water stress, 50% FC and adequate water availability, 80% FC (control). The 50% FC water regime has been used a s a reference, because the growth was higher than the other two treatments. Both 30% and 80% treatments reduced plant height and number of leaves by 25% each, compared to the 50% treatment. A reduction of 40% and 45% in total fresh weight and total dry weights, respectively was caused by the two treatments, 30% FC and 80% FC. Plants grown under 50% FC showed a shift of biomass to leaves and stem. A decrease of 45% and 65% in relative growth rates (RGR) was recorded in plants grown under 30% FC and 80% FC, respectively. The severe water stress treatment (30%) caused a reduction of 50% in Net assimilation rates (NARs), where the adequate water availability (80% FC) resulted in decrease of 80% reduction in NARs.