Rates of nitrogen from nitric and ammoniacal sources required by upland rice genotypes originating from Brazil and Colombia
2016
Hector Augusto Sandoval Contreras | Mario Sandoval Contreras | Renan Ribeiro Barzan | João Pedro Silvestre | Osmar Rodrigues Brito
The aim of this study was to evaluate the initial growth, nitrogen (N) uptake, and agronomic efficiency after the use of N fertilizers in upland rice cultivation. The experiment was conducted in a greenhouse by using pots filled with surface-layer (0 to 20 cm) soil collected from the municipality of Jaguapitã, Paraná. The experimental design was completely randomized with 4 replications. A factorial scheme of 5 × 2 was used, in which the factors were 5 N rates (0, 25, 50, 75, and 100 kg ha-1 N) and 2 cultivars of rice (Fedearroz Lagunas [Colombian] and IAPAR- 9 [Brazilian]). The N sources tested were ammonium sulfate (Experiment I) and calcium nitrate (Experiment II). The following variables were evaluated: number of tillers per pot (NTP), dry mass of the shoots (DMS), N content in the dry mass (NCDM), and agronomic efficiency of N fertilizer (AEN). The data obtained in the experiments were evaluated using analysis of variance, and mean values were compared using Tukey’s test at 5% significance for rice cultivar effects or adjusted to polynomial regression equations for N rates. Use of calcium nitrate yielded higher values of NTP, NCDM, and AEN. The cultivar Lagunas showed higher NTP, while IAPAR-9 showed higher DMS. An increase in N rates, for both sources, resulted in the increase of NTP, DMS, and NCDM; however, AEN was decreased.
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