Effect of Water Stress on Photosynthetic Assimilation and Biomass Accumulation in Olive Tree

The climate change that we are attending in recent years requires a revision of the water resources management in order to en sure a sustainable supply. For this reason, in order to test the plants ability to face water stress, three water stress intensities (100% (T0), 50 (T1) and 25% (T2) field capacity (fc)), for 42 days in a greenhouse under semi-controlled conditions, were applied on 18 olive plants (Olea europaea L. cv 'Meski') of one year old. An evaluation of the response of the olive tree at different water supplies was conducted by monitoring the photosynthetic assimilation, chlorophyll index measured by SPAD, plant growth and dry matter accumulation. The results showed that photosynthesis has increased after 42 days for T0 plants while it increased during the first two weeks before dropping to the 42th day of the application of water restriction (AWR) for T1 plants; a decrease of 26% compared to control treatment. The photosynthetic assimilation of T2 plants has increased at a rate slower until the 28th day AWR then it has dropped after 42 days a decrease of 46% from the witness thus increasing the irrigation dose results in improved photosynthesis. The chlorophyll index fell 2, and 7% compared to the control treatment for T1 and T2, respectively, after 42 days AWR showing that fluid restriction affects the integrity of chlorophylls. Plant growth was shown by the development of a longer root for T2 plants ex plained by the search for minimum quantities of water available. The results showed that the control plants have accumulated more dry matter than stressed plants in the roots and the stem while the underground part/aerial part report seems indifferent to water stress. Water restriction has affected thereby biomass of roots and stems in favor of the leaves, the first operator of the photosyn thetic activity