Efeito das interações entre os íons amônio e nitrato na fisiologia do crescimento do amendoinzeiro

Abstract

Effect of interactions between ammonium and nitrate on the growth physiology of groundnutPeanut is a crop of great importance for the Northeast region, as it is usually grown by small farmers, who on average, do not exceed 10 ha of cultivated area and aim to increase its profitability and diversify the production. This study aimed to evaluate the effect of the relationship between nitrogen forms (ammonium and nitrate) in the initial growth of peanuts. Complete nutrient solution was used with a single concentration of 210 mg N L -1 provided in five proportions of NH 4 + :NO 3 -: 100:0, 75:25, 50:50, 25:75 and 0:100. The experimental units were arranged in completely randomized design, with four replications. The variables evaluated were: shoot length, root length, leaf number, stem diameter, fresh and dry shoot and fresh weight and dry root. The 100:0, 75:25 and 50:50 ratio resulted in decreasing peanut phytomass by ammonium toxicity. However, the 0:100 ratio, nitrate caused a smaller decreased compared to reductions in the highest ammonium concentrations. In the 25:75 and 0:100 ratio, plants grow normally with higher phytomass. The supply of nitrogen in the NH 4 + form only is not a good option for the nutrition of peanuts in early growth stages.

Proporções de amônio e nitrato no crescimento de plantas de Lippia alba (Mill) N. E. Br. cultivadas sob ambientes de luz

“…Trabalhos científicos realizados com o amendoinzeiro e o girassol (Ribeiro et al, 2012;Alves et al, 2013), apresentaram dados que evidenciou-se efeito negativo sobre o crescimento vegetal, quando o nitrogênio só era fornecido na forma amoniacal, isso se atribui à necessidade de utilização dos carboidratos produzidos o que não é desejável para as culturas (Britto & Kronzucker, 2002).…”

Emergence, Growth and Production of Sesame Under Salt Stress and Proportions of Nitrate and Ammonium

“…When analyzing the results obtained for NL in both studied periods together (50 and 70 DAS), the crop has greater preference for the absorption of N in the nitric form. Ribeiro et al (2012) observed that the use of NH 4 + n greater proportions (100/0 and 75/25) inhibited the production of leaves, and, according to these authors, this effect can be attributed to the fact that the carbohydrates translocated from leaves to roots are preferentially used as skeletons of carbon and energy for the process of NH 4 + assimilation, to avoid its accumulation to toxic levels, and not for the processes associated with the growth of this organ. Holzschuh et al (2011) observed, through the analysis of the xylem sap, that NH 4 + negatively affects the absorption of K, Ca and Mg ions, in magnitudes that depend on their concentrations in the environment.…”

“…According to the results, as the ECw levels increased, the dose of NH 4 + above the 100/100 ratio (NO 3 -/NH 4 + ) intensified the deleterious effects on plant production, indicating that the sesame crop absorbs more N in the form of NO 3 -. In a study with peanut plants, Ribeiro et al (2012) also found a reduction in the development of this crop, which resulted in damage to its production, when the crop was subjected to higher proportions of NH 4 + (100/0 and 75/25 of NH 4 + /NO 3 -). This reduction was attributed to restrictions in the water flow of the plant, due to the effects of salinity caused by the NH 4 + ion, which promotes a reduction in the activity of the nitrate reductase enzyme, according to Silva et al (2011).…”

Physiological indices and production of sesame under salt stress and nitrate/ammonium proportions

“…On the other hand, when plants were irrigated with water of 1.2 dS m -1 , the fertilization with higher proportions of ammonical nitrogen (50/150 and 0/200) promoted the lowest TMS (17.61g). Such reduction in the mass of seeds is due to the increase in the proportion of ammonical nitrogen resulting from the restrictions in the absorption of water by the plant caused by the effect of salinity due to the ammonium ion (RIBEIRO et al, 2012), potentiating the effect of irrigation water salinity. These authors also claim that the effects of NH 4 + toxicity have been attributed to the reduction or inhibition of the absorption of cations, especially potassium, as a consequence of the imbalance of ions, which may have negatively influenced the TMS in sesame plants, since Lima et al (2016) observed that the NO 3 -/NH 4 + proportion of 0/100 mg promoted higher mass of seed cotton (27.94 g plant -1 ).…”