Skip to main content
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
item Scagel, Carolyn
item FUCHIGAMI, LESLIE

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.