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- The use of macronutrients and water in marginal Mediterranean areas: the case of carob-treePublication . Correia, P. J.; Martins-Loução, M. A.Carob-tree (Ceratonia siliqua L.) is a sclerophyllous leguminous tree species widely cultivated in whole Mediterranean basin. The fruits (a dry pod) are normally used after crushing to separate seed and pulp, and the seed endosperm is processed to obtain a mucilaginous gum, which is then used in a wide range of commercial food products as a thickener and stabilizer. Contrary to other traditional crops, there is an increasing demand for carob products, which represents a potential benefit to farmers and a diversification of farm incomes. However, current information about the ecology of this crop has not yet been integrated and so there are some doubts about the correct management of natural resources, like water and soil nutrients, in order to improve productivity. These items are particularly important in Mediterranean areas where growth and yield are mostly limited by both climatic and edaphic conditions. In this short communication, some data concerning water and nutrients use (particularly nitrogen) in carob-tree are reviewed.
- Seasonal variations of leaf water potential and growth in fertigated carob-trees (Ceratonia siliqua L.)Publication . Correia, P. J.; Martins-Loução, M. A.Variations of predawn and midday leaf water potential and relative growth rates were studied in mature carob trees (Ceratonia siliqua L. cv "Mulata") submitted to a fertigation experiment. Three levels of irrigation were tested: 0%, 50% and 100%, based on daily standard evaporation values. For each irrigation level two nitrogen amounts were applied - 21 and 63 kg N ha-1 year-l as ammonium nitrate. The experiment was run between July 91 and August 1993. Measurements of leaf water potential and absolute branch length increments were made at monthly intervals, during the entire experimental period or during seasonal growth, respectively. Leaf water potential was related to soil volumetric water content, maximum and minimum air temperature and daily evaporation. Predawn leaf water potentials were always higher than - 1.1 MPa. Midday leaf water potential values presented very large seasonal variations and very low values independent of treatments. The low leaf water potentials observed for the fertigated trees during summer, suggest that this parameter may be related not only to the evaporative demand but also to growth investment. The amount of fertigation was positively correlated with vegetative growth increment and fruit production. Practical implications for irrigation schedules of leaf water potential patterns together with drought adaptation mechanisms of carob tree are discussed.