Nitrate and ammonium ratios in the initial growth of corn plants | Proporciones de nitrato y amonio en el crecimiento inicial de plantas de maíz | Initial development of maize plants grown with different combinations of nitrate and ammonium

Inglés. Corn is one of the main commodities of Brazilian agribusiness, due to its wide use, whether for human or animal consumption, or in the chemical and biofuel industries. Thus, the objective was to evaluate the dynamics of N influenced by different proportions of NO3– and NH4+. The experiment was carried out in a greenhouse, by direct sowing, the seeds were placed at a depth of 1 cm in plastic pots with a capacity of 6 dm3 containing a mixture of previously sieved and washed sand plus vermiculite, in a 2:1 ratio. They were submitted to five proportions of nitrate and ammonium ions (NO3- :NH4+): T1=100:0, T2=75:25, T3=50:50, T4=25:75 and T5=0:100, through nutritious. After 35 days, the following were evaluated: plant height, number of leaves, stem diameter, chlorophyll a, b, total and a/b ratio, root length, leaf fresh matter mass, leaf dry matter mass , stem, roots, total dry matter, and root dry mass/shoot dry mass ratio, leaf area, specific leaf area, leaf area ratio and leaf mass ratio. The excess of nitrate did not favor the increase in the chlorophyll a index of maize plants, which is the most important chlorophyll in the capture of light in the antenna complex. It is not preferable to cultivate corn plants with only nitrate or ammonium, however, the greater amount of nitrate in the culture medium provided better performances in the initial growth of this plant. The proportion with 75% of NO3- is recommended because it presents better performances in most of the analyzed variables.

Español; castellano. El maíz es uno de los principales commodities de la agroindustria brasileña, debido a su amplio uso, ya sea para consumo humano o animal, o en la industria química y de biocombustibles. Así, el objetivo fue evaluar la dinámica del N influenciada por diferentes proporciones de NO3– y NH4+. El experimento se realizó en invernadero, mediante siembra directa, las semillas se colocaron a una profundidad de 1 cm en macetas plásticas de 6 dm3 de capacidad que contenían una mezcla de arena previamente tamizada y lavada más vermiculita, en proporción 2:1 . Fueron sometidos a cinco proporciones de iones nitrato y amonio (NO3- :NH4+): T1=100:0, T2=75:25, T3=50:50, T4=25:75 y T5=0:100, a través de nutrientes . A los 35 días se evaluó: altura de la planta, número de hojas, diámetro del tallo, clorofila a, b, total y relación a/b, longitud de la raíz, masa de materia fresca de la hoja, masa de materia seca de la hoja, tallo, raíces, materia seca total y relación masa seca de raíz/masa seca de brote, área foliar, área foliar específica, relación de área foliar y relación de masa foliar. El exceso de nitrato no favoreció el aumento del índice clorofila a de las plantas de maíz, que es la clorofila más importante en la captación de luz en el complejo antena. No es preferible cultivar plantas de maíz solo con nitrato o amonio, sin embargo, la mayor cantidad de nitrato en el medio de cultivo proporcionó mejores rendimientos en el crecimiento inicial de esta planta. Se recomienda la proporción con 75% de NO3- porque presenta mejores desempeños en la mayoría de las variables analizadas.

Portugués. Corn is one of the main commodities of Brazilian agribusiness, due to its wide use, whether for human or animal consumption or in the chemical and biofuel industries. Thus, this work was carried out to evaluate the influence of different proportions of nitrate and ammonium in the initial development of corn plants. The experiment took place in a greenhouse, by direct sowing, where the seeds were placed at a depth of 1 cm in plastic pots with a capacity of 6 dm3 containing a mixture of previously sieved and washed with vermiculite, in a 2:1 ratio. Five proportions of nitrate and ammonium ions (NO3- :NH4+) were used: T1=100:0, T2=75:25, T3=50:50, T4=25:75 and T5=0:100, through nutrient solutions. After 35 days of cultivation, the following were evaluated: plant height, number of leaves, culm diameter, chlorophyll a, b, total and a/b ratio, root length, leaf fresh matter mass, dry matter mass of leaves, culm, roots, total dry mass, and root dry mass/shoot dry mass ratio, leaf area, specific leaf area, leaf area ratio, and leaf mass ratio. Nitrate as the only source of nitrogen provided a smaller increase in the chlorophyll a index of maize plants, which is the most important chlorophyll in the capture of light in the antenna complex. It is not recommended to cultivate corn plants with only nitrate or ammonium; however, it was observed that high doses of nitrate combined with low doses of ammonium in the culture medium provided satisfactory performance for most variables.