1. Assessment of nitrogen diagnosis methods in sunflower.
- Author
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Tovar Hernandez, Sergio, Diovisalvi, Natalia, Carciochi, Walter Daniel, Izquierdo, Natalia, Sainz Rozas, Hernán, Garcia, Fernando, and Reussi Calvo, Nahuel I.
- Subjects
NORMALIZED difference vegetation index ,DIAGNOSIS methods ,COMMON sunflower ,GRAIN yields ,SUNFLOWERS ,NITROGEN deficiency - 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 (NO3––N) test (PPSNT) and soil N mineralized in short‐term anaerobic incubation (Nan), (b) Greenness index (GI) and the normalized difference vegetation index (NDVI) measured at 6 (V6) and 12 (V12) leaves, and (c) grain nitrogen concentration (Nc). 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 GI, NDVI, N sufficiency index and relative normalized difference vegetation index (NDVIr) were determined at V6 and V12 growth stages. On average, yield response to N was 492 kg ha–1 and Nc 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 V12 allowed monitoring the crop N status with a 0.95 critical threshold. The Nc adequately diagnosed N deficiencies and the critical threshold was 2.26%. Also, Nc was predicted from the ratio between N availability and grain yield (R2 =.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. Core Ideas: Aim: evaluate N diagnosis methods for grain yield and quality of sunflower.Nitrogen mineralized in anaerobic incubation improved the pre‐plant soil NO3––N test.The relative Green Seeker at V12 growth stage was associated with relative yield.Grain N concentration diagnosed N availability in sunflower.The N availability to grain yield ratio defined the N rate required. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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