Nutritional efficiency in sunflower cultivars under dosages of potassium in semiarid region

Potassium (K) participates in critical processes in sunflower cultivation, such as osmotic regulation and translocation of photosynthesis. However, the absorption or accumulation of this nutrient occurs differently owing to edaphoclimatic factors or between cultivars. The objective of this study was to evaluate the nutritional efficiency of sunflower cultivars as a function of different dosage K dosages in a semiarid region. To this end, two experiments were conducted in 2016 and 2017. The treatments consisted of five dosages of K at 0, 30, 60, 90, and 120 kg ha-1 K2O and four sunflower cultivars, Aguará 6, Altis 99, Multissol, and BRS 122. The experimental design was a randomized block with four replications and subdivided plots. The characteristics evaluated were agronomic efficiency, physiological efficiency, recovery efficiency, utilization efficiency, and accumulation of total K in the plant. Sunflower cultivars responded to K dosages in the two crops, with variations in efficiency parameters. Crop 2 showed better nutritional efficiency compared to crop 1. Aguará 6 showed greater nutritional efficiency than the other two crops. The use of dosages between 75 and 91 kg ha-1 of K2O provided better efficiency in K usage for the cultivars.

Economic indicators of nitrogen fertilization in sunflower cultivars / Indicadores econômicos de adubação nitrogenada em cultivares de girassol

Sunflower is one of the most important oilseeds in the world. However, cultivation in semi-arid regions requires analysis of production costs and profitability, ensuring effective decision-making, focused on farming procedures and techniques. In two agricultural crops, 2016 and 2017, experiments were conducted to evaluate the economic indicators of sunflower cultivars ('Aguará 06', 'Altis 99', 'Multissol' and 'BRS 122') submitted to nitrogen (N) doses (0; 30; 60; 90 and 120 kg ha-1) via fertirrigation under semi-arid conditions. The net margin corresponded to the increase of N doses, reaching a maximum net margin in the 2016 harvest of R$ 366.89 ha-1 at the dose of 81 kg ha-1 of N for 'BRS 122'; R$ 577.41 ha-1 with 118 kg ha-1 of N for 'Multissol'; and for 'Aguará 06' (R$ 2,124.00 ha-1) and 'Altis 99' (R$ 976.66 ha-1) at the dose of 120 kg ha-1 of N. In the 2017 harvest, 'BRS 122' obtained R$ 190.90 ha-1 in the dose of 83 kg ha-1 of N and 'Multissol' reached R$ 657.50 in the dose of 85 kg ha-1 of N; the cultivars 'Aguará 06' (R$ 1,078.00 ha-1) and 'Altis 99' (R$ 957.14 ha-1) in the dose of 120 kg ha-1 of N. The rate of return and the profitability index were positive for all cultivars in both crops.

O girassol é uma das mais importantes oleaginosas do mundo. No entanto, o cultivo em regiões semiáridas requer análise dos custos de produção e rentabilidade, garantindo tomadas de decisão eficazes, focadas em procedimentos e técnicas agrícolas. Em duas safras agrícolas, 2016 e 2017, foram conduzidos experimentos para avaliar os indicadores econômicos de cultivares de girassol ('Aguará 06', 'Altis 99', 'Multissol' e 'BRS 122') submetidos a doses de nitrogênio (N) (0; 30; 60; 90 e 120 kg ha-1) via fertirrigação em condições semiáridas. A margem líquida correspondeu ao aumento das doses de N, atingindo uma margem líquida máxima na safra 2016 de R$ 366,89 ha-1 na dose de 81 kg ha-1 de N para 'BRS 122'; R$ 577,41 ha-1 com 118 kg ha-1 de N para 'Multissol'; e para 'Aguará 06' (R$ 2.124,00 ha-1) e 'Altis 99' (R$ 976,66 ha-1) na dose de 120 kg ha-1 de N. Na safra de 2017, 'BRS 122' obteve R$ 190,90 ha-1 na dose de 83 kg ha-1 de N e 'Multissol' alcançaram R$ 657,50 na dose de 85 kg ha-1 de N; as cultivares 'Aguará 06' (R$ 1.078,00 ha-1) e 'Altis 99' (R$ 957,14 ha-1) na dose de 120 kg ha-1 de N. A taxa de retorno e o índice de lucratividade foram positivos para todas as cultivares em ambas as culturas.