Nitrogen Partitioning in Young “Julyprince” Peach Trees Grown with Different Irrigation and Fertilization Practices in the Southeastern United States

Abstract

Fertilizer recommendations for peach cultivation in the southeastern United States were developed decades ago and may not reflect the peach trees’ needs under current cultivation practices. Adequate fertilization for young peach trees induces a balanced vegetative/reproductive growth, ensures efficient resource use, and is environmentally sound. Droughts in the region are becoming more common. Supplemental irrigation for peaches from the time of field establishment serves as insurance in case drought conditions occur and can increase/advance the yield of young peach trees. Our objective was to determine the influence of different fertilizer levels (25, 50, 100, and 200% of the recommended rate), irrigation levels (irrigated vs. non-irrigated), and irrigation systems (drip vs. micro-sprinkler) on nitrogen partitioning and concentration in different organs of young peach trees. The cumulative nitrogen (N) removal per tree was not affected by the different fertilizer levels. Most of the N allocation was accounted for by summer pruning and defoliation (68% of the total N removed). Irrigated trees had higher cumulative N removal after three years than non-irrigated trees, with differences between irrigated vs. non-irrigated trees in most vegetative removal events (winter and summer pruning, and defoliation). Drip-irrigated trees had higher cumulative N removal after three years than micro-sprinkler-irrigated tress, with differences in N removal found in vegetative and reproductive removal events. Differences in N removal were mainly driven by differences in dry weight rather than the N concentration of the organs. These results suggest that different fertilizer levels did not alter the N partitioning in young peach trees, indicating that reduction in fertilizer applications can be done without negative effects. Furthermore, irrigation induced greater vegetative growth, especially under drought conditions, which may result in greater canopy volume and fruit yield compared to non-irrigated trees. Differences between irrigation systems are not consistent; however, drip is more efficient than micro-sprinkler irrigation, with ~38% water savings.