Articles
INFLUENCE OF FOLIAR APPLICATION OF UREA ON TREE GROWTH, FRUIT QUALITY, LEAF MINERALS, AND DISTRIBUTION OF UREA-DRIVED NITROGEN IN APPLES
Article number
594_81
Pages
603 – 610
Language
English
Abstract
Apple (Malus domestica Borkh.) tree responses to foliar urea sprays are variable.
Two separate projects were undertaken to study the influence of foliar urea application on tree growth and fruit quality of Fuji apple and to examine distribution of urea-derived nitrogen (N) in shoots and branches of Golden Delicious apple.
In the first project, effects of monthly applications of three rates of foliar urea [(1.6-3.2 g urea/liter (S1), 4.8-9.6 g urea/liter (S2), and 8.01-16.0 g urea/liter (S3)] and one ground application of nitrogen on young BC-2 Fuji tree growth, precocity, fruit quality at harvest and after storage, and leaf mineral concentrations were studied. BC-2 Fuji apple trees that received a total of 197 g urea (90.6 g actual N) as a ground application over three growing seasons had greater trunk cross-sectional area (TCA), yield per tree, and yield efficiency than trees which received one of the three rates of foliar applications. Fuji trees receiving ground-applied or foliarly-applied urea at the highest rate had the heaviest fruit. Fuji fruit firmness was greatest in the lowest foliar (S1) treatment.
In Fuji apple, ground application resulted in greater than average leaf N in 1994 and the greatest leaf Ca and lowest percentage leaf dry weight, leaf K, Zn, and Cu in both 1993 and 1994. In the second project, three different experiments were conducted to study the distribution of urea-derived N in shoots and branches of Golden Delicious apple trees.
Urea labeled with 15N was applied to young expanding leaves in spring and to senescing spur leaves in fall.
At the low concentrations used [0.5%, 1%, and 2% (w/v)], very little spring-applied 15N was found in tissues other than the treated leaf.
Fall-applied urea-15N, however, was detected in high concentrations in dormant buds and bark of the spurs to which the treated leaves were attached.
The following spring, there was some redistribution of labeled N to adjacent buds.
Foliar urea sprays applied immediately after harvest contributed most to bud N.
Two separate projects were undertaken to study the influence of foliar urea application on tree growth and fruit quality of Fuji apple and to examine distribution of urea-derived nitrogen (N) in shoots and branches of Golden Delicious apple.
In the first project, effects of monthly applications of three rates of foliar urea [(1.6-3.2 g urea/liter (S1), 4.8-9.6 g urea/liter (S2), and 8.01-16.0 g urea/liter (S3)] and one ground application of nitrogen on young BC-2 Fuji tree growth, precocity, fruit quality at harvest and after storage, and leaf mineral concentrations were studied. BC-2 Fuji apple trees that received a total of 197 g urea (90.6 g actual N) as a ground application over three growing seasons had greater trunk cross-sectional area (TCA), yield per tree, and yield efficiency than trees which received one of the three rates of foliar applications. Fuji trees receiving ground-applied or foliarly-applied urea at the highest rate had the heaviest fruit. Fuji fruit firmness was greatest in the lowest foliar (S1) treatment.
In Fuji apple, ground application resulted in greater than average leaf N in 1994 and the greatest leaf Ca and lowest percentage leaf dry weight, leaf K, Zn, and Cu in both 1993 and 1994. In the second project, three different experiments were conducted to study the distribution of urea-derived N in shoots and branches of Golden Delicious apple trees.
Urea labeled with 15N was applied to young expanding leaves in spring and to senescing spur leaves in fall.
At the low concentrations used [0.5%, 1%, and 2% (w/v)], very little spring-applied 15N was found in tissues other than the treated leaf.
Fall-applied urea-15N, however, was detected in high concentrations in dormant buds and bark of the spurs to which the treated leaves were attached.
The following spring, there was some redistribution of labeled N to adjacent buds.
Foliar urea sprays applied immediately after harvest contributed most to bud N.
Authors
E. Fallahi, H. Khemira, T.L. Righetti, A.N. Azarenko
Keywords
apple, fruit quality, nitrogen, urea
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