EFFECTS OF BLENDED NPS AND VERMICOMPOST ON BULB YIELD AND STORABILITY OF ONION (Allium cepa L.) AT HARAMAYA, EASTERN ETHIOPIA

Abstract

Onion (Allium cepa L.) is more response to application of NPS and VC fertilizers. However, optimum dose of these fertilizers has not been identified in the study area. Moreover, in the Haramaya Disterict the yield and shelf life of onion has constrained, due to the farmers use low rate of organic and mineral fertilizers. Therefore, research was conducted at Haramaya University Rare Research site, with the objectives of assessing the effects of blended NPS and VC fertilizers rates on hybrid onion variety bulb yield and shelf live as well as economical rate of fertilizers. The treatments were six levels of blended NPS fertilizer (0, 50, 100, 150, 200, 250 kg ha-1) and three level of VC (0, 2.5, 5 t ha-1) arranged in factorial Randomized Complete Block Design with three replications. Data were collected on phenology, yield and yield related and storage parameters of onion crop and analyzed using SAS (2002)9.1.3 version. Most of the growth, yield and storage parameters were significantly (P<0.05) affected by main and interaction effects of NPS and VC fertilizer. Non fertilized plants in the control treatment were inferior in all parameters. The highest plant height (74.35 cm), leaf number (13.59), above ground fresh biomass (67.94 g plant-1), bulb diameter (7.57 cm), average bulb weight (211.78 g plant-1), total bulb yield (61.79 t ha-1), and unmarketable bulb yield (6.85 t ha-1) of Malbec hybrid onion were recorded from plots that received 250 kg NPS ha-1 + 5 t ha-1VC. On the other hand, maximum marketable bulb yield (55.45 t ha-1) was obtained at the interaction of 200 kg ha-1 blended NPS and 2.5 t ha-1 VC. The maximum leaf length (67.45 cm), physiological maturity (136.36 days), neck thickness (1.34 cm), above ground dry weight (6.05 g plant-), bulb length (6.5 cm) were significantly (P<0.05) increased by main effect of NPS and higher result was recorded at plot received 250 kg NPS ha-1 fertilizer rate. At the end of 14 week of storage period, the total soluble solid was not significantly influenced by main and interaction effect of NPS and VC. Unlike, other storage parameters like physiological loss in weight, percent bulb rotting and sprouting were significantly (P<0.05) influenced by combined application of NPS and VC with maximum values of 24.24, 3.00 and 2.97%, respectively, that recorded at application of 250 kg ha-1blended NPS and nil VC. The study revealed that the highest net benefit of Birr, 505,205.00 and economic returns obtained from the plot received 200 kg ha-1 NPS and 2.5 t ha-1 VC since, it has resulted in highest adjusted marketable bulb yield (49.9 t ha-1) and better storage life. Therefore, after reinvestigation at different location and on different hybrid onion the application of 200 kg ha-1 blended NPS and 2.5 t VC ha-1 rate might be suggested for higher bulb production and higher economic return of hybrid onion in the study area.