Estudio de la eficiencia en el uso del nitrógeno en variedades de olivo

The aim of this work was to determinate whether there are differences for radical uptake of nitrogen and evaluate Nitrogen Use Efficiency (NUE) using different indices. These objectives can help the newly planted varietal choice based on these characteristics. A first experiment was performed in a shadehouse establishing a randomized block design with 10 replications and two levels of nitrogen (0 y 100 ppm). Eight olive varieties were selected for the experiment: ‘Picual’, ‘Hojiblanca’, ‘Arbequina’, ‘Sikitita’, ‘Nevadillo fino’, ‘Frantoio’ ‘Koroneiki’, and ‘Manzanillo cordobés’. In a second experiment a randomized block design was performed with eight replications and two levels of nitrogen (0 y 100 ppm). The experiment was carried-out in a growth chamber with seven olive varieties: ‘Picual’, ‘Arbequina’, ‘Ocal’, ‘Arbosana’, ‘Manzanilla’, ‘Cobrancosa’ and ‘Lechín de Sevilla’. In both experiments, control plants didn’t receive nitrogen and served as control for each variety. A third experiment was aimed at the study of interaction between variety and soil. This experiment was a randomized blocks design with eight replications. The factors were soil type (Terrace, Calcareous, Fertile lowland) and olive variety (‘Picual’ y ‘Arbequina’). Each plant received 100 ppm nitrogen. . In order to determine the initial nitrogen content, a group of plants were growing in plots containing a substrate of sand and peat (2:1) watered only with water. Urea was used as the source of nitrogen in all experiments. The results showed that there were varietal differences in uptake efficiency and nitrogen utilization efficiency, although no relationship between both indices was observed. It was also found an effect of the soil on NUE and a possible interaction between soil and variety in the uptake efficiency, suggesting t hat calcareous soils could affect growth and nitrogen uptake efficiency in sensitive varieties to limestone