Effects of spring soil nitrogen application on nitrogen remobilization, uptake, and partitioning for new growth in almond nursery plants

Abstract

SUMMARYOne year old 'Nonpareil' almond (Prunus dulcis (Mill) D. A. Webb) trees on 'Lovell' rootstocks were used to evaluate the effects of soil nitrogen (N) availability in the spring on N remobilization, uptake, partitioning, and tree growth. After being transplanted to an N-free medium, the trees received a modified Hoagland solution, with or without N from 15 N-depleted NH 4 NO 3 , twice a week for 12 weeks. During the first four weeks, the N used for new shoot and leaf growth mainly came from the nitrogen that had accumulated in storage tissues. No significant differences were seen in the amount and duration of N remobilization between N-fertilized trees and those that received no N. However, trees that were fertilized in the spring had significantly more new shoot and leaf growth. Uptake of 15 N by the roots began two weeks after transplanting. Nitrogen was rapidly taken up from the soil during the period of greatest shoot and leaf growth; leaves were the major sink for N from both root uptake and storage. Six weeks after transplanting, the whole-tree N content was significantly higher in fertilized trees than in the controls. We conclude that the remobilization of N for spring new growth takes place irrespective of the current-year external N supply. However, the new growth in young almond trees is highly dependent on soil N availability, which demonstrates the importance of spring N fertilizer applications following transplantation.

Nutrient Removal by Apple, Pear and Cherry Nursery Trees

“…Nevertheless, nursery is a peculiar growth environment characterised by: i) sandy and poorly structured soils to limit root damages during mechanical tree removal; ii) ultra-high planting density (often >40.000 trees ha -1 ) to best use soil surface and optimise the agronomic management (irrigation, fertilisation, pest and diseases control); iii) high competition among tree roots as a consequence of the high planting density and soil texture. As outcome, nursery trees are more dependent on the mineral uptake than mature trees because of their smaller root size, limited storage reservoirs and reduced vegetative growth (Bi et al, 2004). Therefore, with the aim to promote a fast growth, generous fertilisation rates and irrigation volumes are sometimes adopted (Castle and Rouse, 1990) in commercial nurseries.…”

Nutrient Treatments Used on Field-harvested Colorado Spruce Trees to Maintain Postharvest Quality

“…Previous studies of conifers (Meyer and Splittstoesser, 1971;Millard and Proe, 1993;Nambiar and Fife, 1991) and deciduous plants (Bi et al, 2004;Deng et al, 1989;Millard and Neilsen, 1989) have demonstrated that nitrogen applied during the previous year can strongly affect growth the next year. Poor mineral nutrition while holding trees in a mulch bed may contribute to a reduction in establishment and growth of trees during the first year or more after transplanting.…”