Quiñones Ana, Bañuls Josefina, Millo Eduardo Primo, Legaz Francisco
Departamento de Citricultura y otros Frutales, Instituto Valenciano de Investigaciones Agrarias (I.V.I.A.), Carretera Moncada-Náquera, km 4.5. 46113, Moncada (Valencia), Spain.
J Plant Physiol. 2003 Dec;160(12):1429-34. 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.
采用两种灌溉系统来比较柑橘树的氮素吸收效率，并评估卡里佐枳橙砧木（甜橙×枳）上“纽荷尔”脐橙树[Citrus sinensis (L.) Osbeck]的硝酸根径流情况。这些树用125克标记为K15NO3的氮进行施肥，并种植在装满沙壤土的容器中，置于户外。两组各3棵树分别通过漫灌系统分五次等量施用或通过滴灌分66次施用该氮剂量。在营养生长周期结束时（12月）对树木进行收获，并测定土壤-植物系统中15N/14N的同位素比率。滴灌时整棵树的氮素吸收效率（75%）高于漫灌系统（64%）。在0-90厘米的土壤剖面中，两种灌溉方法固定在有机部分的氮相似（约13%），而以硝酸根形式保留的氮在滴灌下为施用氮的1%，在漫灌下为10%。在后一种情况下，大部分硝酸根留在根系下方，可能会因暴雨或过量浇水而淋失。这些结果表明，滴灌系统除了可能减少淋失损失外，在提高水分利用和肥料氮素吸收方面更有效。
