Proportions of ammonium and nitrate in the initial growth of tobacco plants | Proporciones de amonio y nitrato en el crecimiento inicial de las plantas de tabaco. | Ammonium and nitrate ratios in the cultivation of tobacco plants

English. Tobacco (Nicotiana tabacum L.) is a plant belonging to the Solanaceae family and native to the Americas. Brazil is one of the largest tobacco producers and exporters in the world. This economic importance guarantees the income of many Brazilian families. Knowing that nitrogen is one of the essential macronutrients for plant growth and highly required by tobacco plants, the objective of this work was to analyze the effect of nitrogen sources, in the ammoniacal (NH4+) and nitric (NO3-) form, in tobacco production. The experiment was conducted in a greenhouse at the Federal University of Recôncavo da Bahia, from March to May 2023. The design was completely randomized (DIC), using five proportions of ammonium and nitrate (NH4+:NO3-): 100 :0; 75:25; 50:50; 25:75 and 0:100, with five repetitions. After 60 days of weekly application of the nutrient solution of Hoagland and Arnon (1950) with the respective proportions, the physiological growth parameters were evaluated: the chlorophyll a and b indices; number of leaves; plant height; stem diameter; mass of root and shoot dry matter. The data were submitted to (ANOVA), using the Tukey test at 5% significance. The 75:25 ratio caused greater growth in height, number of leaves, stem diameter and dry leaf mass. In this way, better use of tobacco by ammonia nitrogen allows for greater production. The exclusive supply of nitrate is not recommended for tobacco nutrition, as it resulted in lower plant productivity.  

Spanish; Castilian. El tabaco (Nicotiana tabacum L.) es una planta perteneciente a la familia de las Solanáceas y originaria de América. Brasil es uno de los mayores productores y exportadores de tabaco del mundo. Esta importancia económica garantiza los ingresos de muchas familias brasileñas. Sabiendo que el nitrógeno es uno de los macronutrientes esenciales para el crecimiento vegetal y altamente requerido por las plantas de tabaco, el objetivo de este trabajo fue analizar el efecto de las fuentes de nitrógeno, en forma amoniacal (NH4+) y nítrica (NO3-), en la producción de tabaco. . El experimento se realizó en un invernadero de la Universidad Federal de Recôncavo da Bahia, de marzo a mayo de 2023. El diseño fue completamente al azar (DIC), utilizando cinco proporciones de amonio y nitrato (NH4+:NO3-): 100 :0; 75:25; 50:50; 25:75 y 0:100, con cinco repeticiones. Luego de 60 días de aplicación semanal de la solución nutritiva de Hoagland y Arnon (1950) con las respectivas proporciones, se evaluaron los parámetros fisiológicos de crecimiento: los índices de clorofila a y b; número de hojas; altura de planta; diámetro del tallo; Masa de materia seca de raíces y brotes. Los datos fueron sometidos a (ANOVA), utilizando la prueba de Tukey al 5% de significancia. La proporción 75:25 provocó mayor crecimiento en altura, número de hojas, diámetro del tallo y masa foliar seca. De esta forma, un mejor aprovechamiento del tabaco por el nitrógeno amoniacal permite una mayor producción. No se recomienda el aporte exclusivo de nitrato para la nutrición del tabaco, ya que redundaba en una menor productividad de la planta.

Portuguese. Tobacco (Nicotiana tabacum L.) is a plant of the Solanaceae family and native to the Americas. Brazil is one of the largest tobacco producers and exporters worldwide, and this crop guarantees the income of many small rural producers. Tobacco is very demanding of nitrogen, and adequate levels of this nutrient guarantee longevity of the production chain, maximizing productivity and ensuring quality. Therefore, this study aimed to analyze the effect of ammoniacal (NH4+) and nitric (NO3-) nitrogen in the growth and development of tobacco. A randomized design was applied, using five ammonium and nitrate ratios (NH4+:NO3-): 100:0; 75:25; 50:50; 25:75 and 0:100, with five replications. After 60 days of weekly application of the solution, physiological and growth parameters were assessed: chlorophyll contents a and b; number of leaves; plant height; stem diameter; root, stem, leaf, shoot and total dry mass. The 25:75 ratio (NH4+:NO3-) resulted in an increase of height, number of leaves, stem diameter and leaf dry mass, the latter being the variable of greatest commercial relevance for tobacco cultivation. The highest chlorophyll contents were found under the 100:00 ratio (NH4+:NO3-) supplementation; however, this treatment had the lowest expressions in all other variables and is not recommended for tobacco cultivation.