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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Research Unit » Research » Publications at this Location » Publication #148604

Title: SPRING GROWTH OF ALMOND NURSERY TREES DEPENDS UPON BOTH NITROGEN RESERVES AND SPRING NITROGEN APPLICATION

Author
item GUIHONG, BI
item Scagel, Carolyn
item CHENG, LAILIANG
item DONG, SHUFU
item FUCHIGAMI, LESLIE

Submitted to: Journal of Horticultural Science and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2003
Publication Date: 11/1/2003
Citation: Bi, G., Scagel, C.F., Cheng, L., Dong, S., Fuchigami, L.H. Spring growth of almond nursery trees depends upon both nitrogen reserves and spring nitrogen application. Journal of Horticultural Science and Biotechnology. 78(6): 853-858.

Interpretive Summary: Understanding the relative contribution of reserve N and N from spring applications of fertilizer to the new growth of almond nursery trees has direct practical implications. If new growth is mainly determined by levels of N reserves, cultural practices in the nursery should be optimized to improve the amount of N reserves in trees. However, if new growth is mainly determined by uptake of N from fertilizer applications in spring, management strategies directed at optimizing fertilizer uptake would improve the regrowth performance. Almond nursery trees were fertigated with five nitrogen (N) concentrations from July to September. Trees were sprayed with water or urea in October, harvested bareroot and stored at 20C. Trees were transplanted into an N-free medium in the spring after cold storage and supplied with either N-free fertilizer or fertilizer containing 15N. N concentrations in both stem and root tissues were positively correlated with nitrogen fertigation concentration. Foliar urea application increased stem and root N regardless of N fertigation concentration from the prior season. Both N reserves and N from spring fertilizer application were used during tree growth in the spring. Trees with higher levels of N reserves used more of these reserves for new growth than those with lower N reserves. Trees with low levels of N reserves primarily used N from spring application of fertilizer for growth of new shoots and leaves. Both reserve N and spring applications of N are important for the regrowth performance of barerooted almond nursery trees during establishment in the spring. Application of N in the spring can improve almond nursery tree performance, especially for the trees with low N reserves.

Technical Abstract: June-budded 'Nonpareil/Nemaguard' almond (Prunus dulcis (Mill) D. A. Webb) trees were fertigated with five nitrogen (N) concentrations (0, 5, 10, 15, and 20 mM) from July to September. Trees were sprayed with water or 3% urea in October, harvested bareroot after natural leaf fall, and stored at 20C. One set of trees were destructively sampled for total N content, and the remaining trees were transplanted into an N-free medium in the spring after cold storage. After budbreak, trees were supplied with either N-free Hoagland solution or Hoagland solution containing 15N-NH4NO3 for 70 days. N concentrations in both stem and root tissues were positively correlated with nitrogen fertigation concentration. Foliar urea application increased stem and root N regardless of N fertigation concentration. Both N reserves and N from spring fertilizer application were used during the first 70 days of tree growth in the spring. The amount of N reserves used for the growth of new shoots and leaves depended on the total amount of N reserves. Trees with higher levels of N reserves used more of these reserves for new growth than those with lower N reserves. The amount of N from spring fertilizer application that was used for the growth of new shoots and leaves was affected by the total N reserves available. Trees with low levels of N reserves primarily used N from spring application of fertilizer for growth of new shoots and leaves. We conclude that both reserve N and spring applications of N are important for the regrowth performance of barerooted almond nursery trees during establishment in the spring. Application of N in the spring can improve almond nursery tree performance, especially for the trees with low N reserves.