AGRONOMIC AND QUALITATIVE PERFORMANCE OF DENSELY CULTIVATED ONION CULTIVARS AS AFFECTED BY POTASSIUM FERTILISATION

ABSTRACT The increase in plant density, combined with the use of hybrids in onion cultivation, has provided significant gains in yield, with a direct impact on the amount of absorbed macronutrients. The present work aimed to evaluate the yield and quality of two onion cultivars under a densified system as a function of potassium doses supplied via fertirrigation. A randomized complete block design was used in a 2 x 7 factorial scheme with four replications. The treatments consisted of two cultivars (IPA 11 and Rio das Antas) and seven potassium doses (0, 70, 140, 210, 280, 350 and 420 kg ha-1 K2O), provided by fertigation. The potassium doses that provided maximum total and commercial yields were 215 and 216 kg ha-1 of K2O, respectively. The soluble solids and the percentage of bulbs of classes 2, 3 and 4 were not influenced by potassium fertilization. There was a reduction in the percentage of non-commercial bulbs with the increase of potassium doses. The dose with maximum economical efficiency was 210.6 kg ha-1 of K2O, responsible for a commercial yield of 61.8 t ha-1.