O azoto no crescimento e na produtividade de jovens pereiras 'Rocha' | Nitrogen fertilization on growth and productivity of young 'Rocha' pear trees
2009
Varennes, A. | Neto, C. | Carranca, C. | Rocha, I. | Sobreiro, J. | Clemente, J.
Pear trees (Pyrus communis L. ‘Rocha’) grafted on quince ‘BA29’ were planted in February of 2003 at “Pêro Moniz” (“Cadaval”, Portugal) and drip-fertigated for three years with four N levels (0, 10, 20 and 40 kg N/ha per year) using ammonium nitrate. At planting and at the end of each season, tree height (A), trunk cross sectional area (AST) and the number of shoots and shoot length (NL and CL) were determined. Leaves were collected 110 days after full bloom (DAPF) and at leaf fall and were chemically analysed for N. The onset of flowering was in 2005 and in that year the fruit set and the yield characteristics were evaluated. Moreover, in 2005 five extra trees were selected for each N level, and all flowers were collected and analysed. Most growthcharacteristics were irresponsive to N fertilization. In the third year the AST differed between N levels, whereas CL responded to N supply at the end of the first year of fertilization. The leaves N concentration varied in response to N supply. The control presented fewer flowers and the highest N level resulted in a greater flower production. Flower N concentration was lower at the intermediate N levels. Fruit set and yield were not significantly different between N treatments. Fruits from the highest N level presented lower pulp firmness and a bigger starch regression index, indicating a more advanced maturation stage than the fruits from other N levels.
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