Effect of Plant Spacing and Np Fertilizer Levels on Growth, Seed Yield and Quality of Onion (Allium cepa L.) at Shewa Robit, Northern Ethiopia

The shortage of quality seed is the major limiting factor of onion production in the study area. Inappropriate use of NP fertilizers and plant spacing is the major source of the problem.

The experiment was conducted to determine optimum plant spacing and NP fertilizer for high yield and quality seed production of onion.

The treatments were composed of plant spacing 10×20×40 cm, 20×30×50 cm, 10×40 cm, 10×50 cm, 10x30 cm and NP fertilizer levels 86.25 P₂O₅ & 85.5 N kg ha^-1, 115 P₂O₅ & 114 N kg ha^-1, 143.6 P₂O₅ & 142.5 N kg ha^-1, 69 P₂O₅ & 142 N kg ha^-1 and control in a 5 x 5 factorial arrangement of RCBD with three replications.

The highest seed yield per hectare (879.4 kg) and per plot (663.6 g) was obtained from 115 P₂O₅ & 114 N kg ha^-1 fertilizers and plant spacing 10×30cm gives the highest seed yield per plot (561.7g) and per hectare (748.9 kg). The highest germination percentage was obtained by the interaction effect of 10×30 cm and 143.6 P₂O₅ & 142.5 N kg ha^-1. Whereas, highest seed vigor index I and II were obtained from the interaction of 115 P₂O₅ &114 N kg ha^-1 and 20×30×50 cm spacing.

Plant spacing of 10×30 cm followed by 20×30×50 cm and 115 P₂O₅ &114 N kg ha^-1 fertilizers could be recommended for high yield and quality onion seed production in the study area.