Volume 55 Number 2 Article 11
Year 2001 Month 4
Title: Optimum Ranges of Leaf Nitrogen for Yield Fruit Quality, and Photosynthesis in ŽBC-2 Fuji` Apple
Authors: E. Fallahi, W.M. Colt, and B. Fallahi
Abstract:
The influence of five rates of ground-applied nitrogen (N) on yield, fruit quality attributes (fruit size,
color, firmness, soluble solid concentrations, and starch), and leaf mineral concentrations and photosynthesis in 'BC-2 Fuji' apple [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] trees were
studied to determine optimum ranges of leaf N for quality fruit and yield.
Fruit skin red color decreased
as the rate of N increased.
Under the environmental conditions of this experiment, annual ground application of N for optimum fruit quality should be more than 31.8 g/tree/year but less than 99.8
g/tree/year, preferably about 65.8 g/tree/year.
Optimum leaf N should be between 2.00% and 2.10% dry
weight (preferably about 2.05% dry weight) in a light-crop year or an "off-year" and more than 2.22%
but less than 2.38% dry weight (preferably about 2.30% dry weight) in a heavy-crop year or an "onyear"
for production of high quality fruit.
Leaf K decreased while leaf Mg and Mn increased with increase in N application.
Fall application of N often resulted in lower leaf N, thus, better fruit color.
Other
fruit quality attributes were not consistently affected by time of N application.
Leaf net photosynthesis
(Pn) decreased between mid-Jun and mid-August.
Trees receiving 31.8 g N/tree/year had lower leaf Pn
than those receiving higher rates of N.
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