Functional adaptations of fig trees (ficus carica, l.) In agroecosystems of the western mediterranean desert of Egypt.
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The ecophysiological characteristics of fig (Fi'cus carica, L.) trees, growing with maximum activity during the hot and dry summer, were studied in relation to growth, carbon partitioning, nutrient balance and water use. The initiation of growth was dependent on carbohydrate reserves (estimated usage = 62%). The trees enhanced their short growth span by rapid increase in leaf area associated with high photosynthetic rate early in the season, allowing a storage of 20% of net assimilate produced for latter use. High net primary production (3200 kgDM ha~') was the result of a high relative growth rate. About 46% of this production contributes to ligneous structure of the agroecosystem. Fig trees exhibited a positive nitrogen balance, among other nutrients, as a result of withdrawing nutrients prior to leaf abscision except for the excess calcium which is removed through litter. However, large quantities of resources are harvested within fruits, hence fertilizer application is essential for maintenance of yield. Although fig trees exhibited efficient water uptake and water use capacities, yet supplementary irrigation in years of below average rainfall is also important to maintain the relatively high transpiration rate and high annual water output.