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Pear tree nutrition. 4. Effects of different nitrogen supply via roots or leaves on yield, fruit size and fruit quality of 'Moltke' pear.

Ystaas, J.;

Acta Agriculturae Scandinavica Year: 1990 Vol: 40 Issue: 4 Pages: 357-362

1990

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Pear tree nutrition. 4. Effects of different nitrogen supply via roots or leaves on yield, fruit size and fruit quality of 'Moltke' pear.

In a 12-year experiment at Ullensvang on the N requirements of Moltke pear trees on seedling rootstocks, annual soil applications of 0, 93, 186 or 279 kg N/ha as Ca(NO3)2 in the spring were compared with an annual single postharvest spray of 6% urea in mid-Oct. Trees showed only small responses to increasing N rate. Average leaf N content at the end of Aug. was 2.03% in control trees compared with 2.20% in trees receiving 279 kg N/ha annually. Increasing N rate had no effect on trunk cross-sectional area, fruit set, yield, yield efficiency, fruit size or fruit quality. Yield was significantly related to leaf N contents in the range of 1.70-2.75% N. Crop load exerted a significant effect on fruit quality. It is concluded that pear tree roots exhibit a highly buffered reaction to N uptake and that the pear fruit is insensitive to increasing N fertilizer rates.