Effects of (15)N application frequency on nitrogen uptake efficiency in Citrus trees

• Published in: Journal of plant physiology Vol. 160; no. 12; pp. 1429 - 1434
• Main Authors: Quinones, A, Banuls, J, Millo, E.P, Legaz, F
• Format: Journal Article
• Language: English
• Published: 2003
• Subjects: absorption; analysis; Citrus; Citrus sinensis; drug effects; fertilizer application; Fertilizers; flood irrigation; fruit trees; growth & development; isotopes; metabolism; microirrigation; nitrates; nitrogen; nitrogen content; nitrogen fertilizers; Nitrogen Isotopes; nitrogen uptake efficiency; nutrient uptake; pharmacology; Plant Structures; Potassium Compounds; Soil; soil profiles; soil-plant interactions; Water; Water Movements
• ISSN: 0176-1617
• DOI: 10.1078/0176-1617-01018

Two irrigation systems were used to compare nitrogen uptake efficiency in citrus trees and to evaluate the NO3(-) runoff in Navelina orange trees [Citrus sinensis (L.) Osbeck] on Carrizo citrange rootstock (Citrus sinensis x Poncirus trifoliata Raf.). These were fertilized with 125 g N as labelled K15NO3 and grown outdoors in containers filled with a sand-loamy soil. Two groups of 3 trees received this N dose either in five equally split applications by a flooding irrigation system or in 66 applications by drip. Trees were harvested at the end of the vegetative cycle (December) and the isotopic ratios of 15N/14N were measured in the soil-plant system. The N uptake efficiency of the whole tree was higher with drip irrigation (75 %) than with flooding system (64 %). In the 0-90 cm soil profile, the N immobilized in the organic fraction was similar for both irrigation methods (around 13 %), whereas the N retained as NO3(-) was 1% of the N applied under drip and 10% under flooding. In the last case, most of NO3(-) remained under root system and it could be lost to leaching either by heavy rainfalls or excessive water applications. These results showed that a drip irrigation system was more efficient for improving water use and N uptake from fertilizer, in addition to potentially reduced leaching losses.