ABSTRACT
Effect of Nitrogen, Phosphorus and Potassium rates, sources and forms upon onion (Allium cepa) bulbs yield and quality.

Nicasio Rodríguez S.1, Ciro Belmar N. y Adriana Valenzuela P.
 

Six fertilisation experiments were established in order 10 study the use of nitrogen, ,phosphorus and potassium applied at different rates, sources and application forms in onion (Allium cepa) cv. Sintética. The study aimed to evaluate the effect of N, P and K fertilisation upon onion bulb production and storage quality. The experiments were carried out during 1993/94 and 1994/95 and the experimental layout was a factorial design with three replications. Yield, plant height, number of leaves, polar and equatorial diameters were measured. During storage the percentage of bulb weight loss and the number of bulbs exhibiting disease symptoms at 65, 97, 132 and 187 days afterharvest were measured. Data showed a significant effect of N (P< 0.05) up to 150 kg N ha-1. Significant effects of P and K rates could not be detected nor statistic interactions between N and P. A statistically significant effect of P applied as Normal Superphosphate was observed. N applications affected the number of leaves and plant height, and a significant increase of bulb diameter was observed with N applications. N applications increased weight losses of stored bulbs only during the season 1993/94. The percentage of diseased onion bulbs was not affected by fertilisation.

Keywords: onions, fertiliser rates, fertiliser sources, fertiliser forms.
1 Instituto de Investigaciones Agropecuarias, Centro Regional de Investigación Quilamapu, Casilla 426, Chillán. Chile. E-mail: nrodrigu@inia.cl.