The effect of water stress on growth and dry matter distribution in juvenile Sesbania sesban and Acacia nilotica

Abstract

A comparison was made of the early growth and dry matter partitioning between the roots, stems and leaves of Sesbania sesban subsp. rubica and Acacia nilotica subsp. indica. Plants were grown in pots in the open in Northern Oman between January and March. A number of plants of each species were subjected to a prolonged, mild water stress. This was achieved by reducing the quantity of daily irrigation water for 70 days beginning 24 days from seedling emergence. Non-stressed plants of S. sesban produced a larger biomass than A. nilotica during the period of measurement. However, water stress produced a proportionately greater decrease in mean plant dry weight in S. sesban than in A. nilotica after 94 days of growth. During the 94 days of the experiment the mean relative growth rate decreased in non-stressed and water-stressed plants of both species as a result of a decline in mean unit leaf rate. Water-stressed plants of both species had a higher mean leaf area ratio than non-stressed plants. The results demonstrate that leguminous species from arid habitats may be more suitable alone or mixed with tropical species, for use in arid zone agriculture as a multipurpose tree and shrub.