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Corn is among the main agricultural products produced in Brazil, mainly due to its importance in human and animal food. Corn productivity is mainly related to climatic conditions and nutritional management, especially concerning nitrogen. The study's objective was to evaluate the response of corn hybrids subjected to nitrogen doses in a low-altitude subtropical environment. The experiment was conducted in the agricultural year of 2019/2020 in the municipality of Santa Maria-RS. The experimental design was of completely randomized blocks in a subdivided plot. Four corn hybrids, DKB 240 PRO 3, DKB 290 PRO 3, DKB 345 PRO 3, and Ag 9025 were used as the main plot, and six doses of nitrogen, 0, 50, 100, 150, 200, and 250 kg ha-1 in subplots. We evaluated the number of grain rows (NR) per cob, number of grains per row (NGR), cob length (CL, cm), average grain length (GL, cm), total grain weight per cob (GWC, g), thousand-grain mass (TGM, in g), and grain yield (YIE, in kg ha-1). The data were submitted to the analysis of variance (F test), and the means were compared by the Scott-Knott test at 5% of error probability and submitted to regression analysis. Cultivar Ag 9025 had the highest grain yield, associated with the highest CL, GL, GWC, TGM. The higher GL associated with high TGM compensated for the lower averages of NR and NGR for this cultivar. The maximum technical efficiency for the cultivars was 196.22 kg ha-1 of nitrogen. The mass economic efficiency with commercial values of the 2019/2020 harvest for the cultivars was 185.84 kg ha-1. [ABSTRACT FROM AUTHOR]

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The objective of the work was to evaluate the response of growth and production, the interception efficiency of photosynthetically active radiation, the extinction coefficient, and the productivity components of sunflower in with the use of cover nitrogen doses in subtropical environments. The experiment was conducted at Santa Maria-RS, Brazil, where they were evaluated the leaf area index (LAI), interception efficiency (εi), and extinction coefficient (k) of photosynthetically active radiation (PAR), plant height (PH), chapter diameter (CPD), stem diameter (SD), the mass of one thousand achenes (MTA), and grain productivity (PROD) were evaluated. Nitrogen doses influenced the LAI only at 52 and 65 DAE, while the canopy interception efficiency (CIE) was influenced at 36, 42, 52, and 86 DAE. Therefore , for growth and production doses of cover N positively influence stem diameter and grain productivity. The application of cover nitrogen fertilizer linearly and positively affects the sunflower crop, and 160 kg ha-1 N. Interception efficiency of photosynthetically active radiation by the canopy and the leaf area index are positively influenced by the doses of nitrogen in the canopy. The extinction coefficient of the photosynthetically active radiation in sunflower decreases with the increasing dose of cover N. [ABSTRACT FROM AUTHOR]

Copyright of Scientia Agraria Paranaensis is the property of Revista Scientia Agraria Paranaensis and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista de Ciencias Agroveterinarias is the property of Revista de Ciencias Agroveterinarias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)