Yield and profitability of flooded rice genotypes in relation to nitrogen doses and phosphorus and potassium application

Produtividade e rentabilidade de genótipos de arroz irrigado em função de doses de nitrogênio e aplicação de fósforo e potássio

ABSTRACT

The use of hybrid genotypes is a good alternative for increasing the flooded rice yield. However, there is a need for validation of the fertilizer management under different edaphoclimatic conditions and its greater profitability. This study aimed to evaluate the grain yield and profitability of rice hybrids in relation to N doses and fertilization with P and K. Five hybrid cultivars and the conventional IRGA 424 CL cultivar combined with four N doses (0, 100, 150 and 200 kg ha^-1) were evaluated, all with fixed doses of 90 kg ha^-1 of P₂O₅ and 150 kg ha^-1 of K₂O, besides an additional treatment without the addition of fertilizers. The N application increases, on average, by 10 and 35 % the flooded rice yield in years with favorable and unfavorable climatic conditions, respectively. Regardless of the year and genotype, the highest yields are obtained with doses of N between 106 and 200 kg ha^-1, with the most profitable dose being the 150 kg ha^-1 one (22 % higher than for the absence of N). The hybrids produce an average of 20 % more grains than the IRGA 424 CL cultivar, increasing the profitability by 18 %. In soil with adequate P and K availability, there is no increase in yield due to the application of these nutrients. However, in deficient soil, the fertilization with P and K increases the grain yield by 21 %.

KEYWORDS:
Oryza sativa; hybrid seed; fertilization response curve; plant nutrition