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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Research Unit » Research » Publications at this Location » Publication #153589
Title: SPRING SOIL NITROGEN APPLICATION IN RELATION TO NITROGEN REMOBILIZATION, UPTAKE, AND PARTITIONING FOR NEW GROWTH IN ALMOND NURSERY PLANTS

Author
item GUIHONG, BI - OSU
item Scagel, Carolyn
item FUCHIGAMI, LESLIE - OSU

Submitted to: ASHS Centennial Conference
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2003
Publication Date: 10/3/2003
Citation: Guihong, B.I., Scagel, C.F., Fuchigami, L. SPRING SOIL NITROGEN APPLICATION IN RELATION TO NITROGEN REMOBILIZATION, UPTAKE, AND PARTITIONING FOR NEW GROWRH IN ALMOND NURSERY PLANTS. ASHS Annual Meeting Abstracts. 2003. 38(5) p. 850

Interpretive Summary: In deciduous fruit trees, nitrogen (N) used for new growth in the spring may come from two sources: N stored from the previous year and N uptake during the current year. Compared with mature trees, nursery trees may be more dependent on uptake of N from soil because of the smaller tree size, limited storage reservoir, and vigorous vegetative growth. Understanding the effects of spring soil N supply on N remobilization, uptake, and vegetative growth in young almond trees is important for optimizing the timing of fertilizer application to meet tree uptake and demand. One-year-old 'Nonpareil/Lovell' almond (Prunus dulcis) plants were used to evaluate the effects of soil N availability in the spring on N remobilization, uptake, and tree growth. After transplanting, trees received fertilizer with or without 15N-labelled NH4NO3 for 12 weeks. Application of N fertilizer to soil in the spring increased new growth of young almond trees.Uptake of N from the soil started two weeks after N application, and is correlated with rate of new growth in the spring.The maximum N uptake occurred during the period of rapid new shoot and leaf growth. Trees receiving N fertilization in the spring had N contents approximately three times higher than trees that received no nitrogen. Our results suggest that soil application of N fertilizer in spring during the period of rapid new shoot and leaf growth can significantly improve vegetative growth and N status in young almond trees. We conclude that the remobilization of N for spring new growth takes place irrespective of the current external N supply. However, the new growth of young almond plants is highly dependent on soil N availability which indicates the importance of N fertilizer applications in spring to almond nursery trees after transplanting.

Technical Abstract: The objectives of this study were to (1) determine whether soil N application alters nitrogen (N) remobilization; (2) quantify the effects of soil N availability in the spring on N uptake, distribution and new growth; and (3) determine the most efficient time for spring soil N application for one-year old almond nursery trees.One-year-old 'Nonpareil/Lovell' almond (Prunus dulcis (Mill) D. A. Webb) plants were used to evaluate the effects of soil N availability in the spring on N remobilization, uptake, partitioning and tree growth. After transplanting in spring, trees received fertilizer with or without 15N-labeled NH4NO3 for 12 weeks. During the first 4 weeks after transplanting, N used for new growth mainly came from N remobilized from storage tissues. At the end of the experiment, 49% of the total tree N was remobilized from storage for new growth. There was no significant difference in the amount and duration of N remobilization between N-fertilized trees and trees that received no N. Trees receiving N fertilizer in the spring had significantly more new growth than those that did not receive N. Uptake of 15N by roots occurred two weeks after transplanting. Rapid uptake of N from soil occurred during the period of rapid shoot and leaf growth and leaves were the major sink for N from both root uptake and storage. Whole tree N content was higher in N-fertilized trees than those receiving no N approximately six weeks after transplanting. We conclude that the remobilization of N for spring new growth takes place irrespective of the current external N supply. However, the new growth of young almond plants is highly dependent on soil N availability which indicates the importance of N fertilizer applications in spring to almond nursery trees after transplanting.