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Assessment of nitrogen diagnosis methods in sunflower
Author(s) -
Tovar Hernandez Sergio,
Diovisalvi Natalia,
Carciochi Walter Daniel,
Izquierdo Natalia,
Sainz Rozas Hernán,
Garcia Fernando,
Reussi Calvo Nahuel I.
Publication year - 2021
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.1002/agj2.20685
Subject(s) - helianthus annuus , sunflower , normalized difference vegetation index , nitrogen , zoology , mathematics , agronomy , grain yield , yield (engineering) , fertilizer , chemistry , leaf area index , biology , materials science , organic chemistry , metallurgy
Abstract Nitrogen deficiency can severely limit sunflower ( Helianthus annuus L.) grain yield and quality. Our objective was to evaluate N diagnosis methods based on: (a) pre‐plant soil nitrate‐nitrogen (NO 3 – –N) test (PPSNT) and soil N mineralized in short‐term anaerobic incubation (Nan), (b) Greenness index (G I ) and the normalized difference vegetation index (NDVI) measured at 6 (V 6 ) and 12 (V 12 ) leaves, and (c) grain nitrogen concentration (N c ). Seventeen experiments were carried out between 2010 and 2019 in Argentina, evaluating nine N rates (0, 30, 40, 60, 80, 90, 120, 150, and 160 kg N ha –1 ). The G I , NDVI, N sufficiency index and relative normalized difference vegetation index (NDVIr) were determined at V 6 and V 12 growth stages. On average, yield response to N was 492 kg ha –1 and N c response was 0.25% in 9 and 11 responsive experiments, respectively. The inclusion of Nan improved the PPSNT diagnosis method. The critical N availability (PPSNT + fertilizer N) threshold was 115 kg N ha –1 for experiments with low Nan (<60 mg kg –1 ), and 90 kg N ha –1 for experiments with high Nan (>60 mg kg –1 ). The NDVIr at V 12 allowed monitoring the crop N status with a 0.95 critical threshold. The N c adequately diagnosed N deficiencies and the critical threshold was 2.26%. Also, N c was predicted from the ratio between N availability and grain yield ( R 2 = .39). Our results would allow to better estimate N availability to recommend adequate N fertilizer rates for sunflower aiming to optimize grain yield and quality, and minimize the economic and environmental cost of fertilization.