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Abstract
In a 12-year study of nitrogen fertilization of ‘Moltke’ pear trees soil applications of calcium nitrate in the spring were compared to feeding pear trees by a single 6% postharvest urea spray in mid-October. Despite heavy dressings (Nil, 93, 186 and 279 kg N ha-1) the trees showed only small responses to differential nitrogen fertilization. The leaf nitrogen content by the end of August of control trees averaged 2.02% as compared to 2.20% of trees receiving 279 kg N ha-1 annually. No effect of different nitrogen applications on trunk cross-sectional area, fruit set, yield, yield efficiency, fruit size and fruit quality was found. Within the range of 1.70–2.75% leaf nitrogen yield was significantly related to the leaf nitrogen levels. Crop load exerted a significant negative effect on fruit quality. It is concluded that the roots of pear trees exhibit a highly buffered reaction to nitrogen uptake and that the pear fruit is insensitive to differential nitrogen fertilization.