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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.
- Leaf nutrient variation in mature carob (Ceratonia siliqua) trees in response to irrigation and fertilizationPublication . Correia, P. J.; Martins-Loução, M. A.Seasonal variations in leaf nitrogen, phosphorus and potassium concentrations were studied in a mature carob (Ceratonia siliqua L. cv ‘‘Mulata’’) orchard subjected to a 4-year irrigation and fertilization experiment. Three irrigation regimes (0, 50 and 100%), based on the evaporation values obtained from a class A pan, were tested in combination with two nitrogen (N) supply regimes in which 21 kg ha-1 year-1 (low-N) and 63 kg ha-1 year-1 (high-N) were supplied as ammonium nitrate. Leaf nitrogen concentration increased throughout the experiment, independently of treatments. There were no significant differences in leaf N concentration between trees in the high-N and low-N treatments. Irrigation regimes had no effect on leaf mineral concentration but influenced the amount of leaves shed and slightly modified the pattern of leaf shedding that occurred during the summer drought period. Nutritional balances between N and P and N and K were both closely and significantly correlated. Potassium was translocated from leaves to fruits during spring, independently of treatments. Severe water stress periods occurring during spring or autumn induced shedding of leaves leading to nutrient mobilization. Nutrient retranslocation during these drought periods may represent an adaptive mechanism. Nitrogen retranslocation was higher for trees in the high-N treatments than for trees in the low-N treatments, whereas phosphorus retranslocation was independent of the irrigation and fertilization treatments.