Effects of storage duration and bulb sizes on physiological losses of Agrifound light red onion bulbs (Allium cepa L.)

M.S. Abubakar1*, J.N. Maduako2, M. Ahmed3

1Department of Soil Science, Faculty of Agriculture, Federal University Dutse, P.M.B 7156 Dutse, Jigawa State, Nigeria
2Department of Agricultural and Environmental Engineering, School of Engineering and Engineering Technology, Federal University of Technology Owerri, P.M.B 1526 Owerri, Imo State, Nigeria
3Department of Crop Science, Faculty of Agriculture, Adamawa State University, P.M.B 25 Mubi, Adamawa State, Nigeria

(Manuscript received 9 July 2018; accepted for publication 8 January 2019)

Abstract. The effect of storage duration and bulb sizes on physiological losses of the Agrifound light red onion bulbs stored in an Improved Naturally Ventilated Storage Structure-INVSS (constructed using locally available materials like; sand, cement, wood, corn stalks, wire mesh and grasses) under room condition was studied in 2012. Dry and wet bulb thermometers were installed to measure ambient temperature and relative humidity. Wind velocity was measurement by hand held Anemometer. The onion bulb samples were sorted and graded into three standard size categories (small: <50mm; medium: 50-70mm and jumbo: >70mm in diameter) and kept in the INVSS at the Department of Agricultural and Environmental Engineering Research Farm of Modibbo Adama University of Technology (MAUTECH), Yola. The samples were monitored and data taken on a daily basis for a period of twenty (20) weeks. The data were analyzed with ANOVA in CRD and the means were separated using LSD at p<0.05. The results indicated that storage duration had significant effects (p≤0.05) on weight, rot and sprout losses. Jumbo size onion bulbs had the highest Storage Weight Loss (SWL) by a mean of 5.1%, followed by medium and small size onion bulbs with means of 4.8% and 4.2%, respectively. Storage Sprout Losses (SSL) studied in the three of onion bulb sizes showed higher SSL among the small size Agrifound light red variety than the medium size onion bulbs with respective mean values of 5.0% and 3.8%, while the least value of SSL (2.6%) was observed in Jumbo size onion bulbs. Similar comparison was also made in terms of Storage Rot Losses (SRL) and it showed that relatively higher SRL among the Jumbo size onions (3.3%), followed by medium sizes (3.1%) while the least was observed from the small sizes (2.3%). The findings recommend that the INVSS should be used to store Jumbo and small size onion bulbs for at least 5 months to achieve minimum storage losses. Though, it is not cost effective to store medium size onion bulbs in the INVSS for more than 4 months.

Hot-water treatment of gladiolus cormels for control of corm-borne fungal diseases

S. Bistrichanov1, T. Vatchev2, Z. Avramov1*

1University of Forestry, 10 Kliment Ohridski, 1797 Sofia, Bulgaria
2Institute of Soil Science, Agrotechnologies and Plant Protection, 35 Panayot Volov, 2230 Kostinbrod, Bulgaria

(Manuscript received 18 May 2016; accepted for publication 23 January 2017)

Abstract. A hot-water treatment was used successfully to obtain pathogen-free planting stock from various plants to control some diseases including gladiolus. The objective of this study was to evaluate the effect of hot-water treatments in terms of damaging gladiolus, concerning sprouting and leading to crop loses. Cormels of two gladiolus cultivars, Oscar and Amsterdam, were used for each treatment (temperature x time period) and were immersed in water baths with hot water at 20 ̊C (as control), 45 ̊C, 50 ̊C, 55 ̊C and 60 ̊C for different treatment periods 10, 20 and 30 min and were planted in pots (d10cm) filled with sterile nutrient substrate (peat:soil:perlite in ratio 3:1:0.5). Three replicate pots each containing 10 cormels were used per treatment. The results showed that the increase of the temperature and the extension of exposition duration reduced significantly the percentage of the sprouting plants from both cultivars – more than 80% at 55 ̊C/20min, and Oscar was more resistant to this treatment regime. For phytosanitary purposes two treatment options were considered as non- damaging – 45 ̊C for 30min or 50 ̊C for 20min, wherein the resulting plants showed approximately 90% sprouting. It was concluded that for successful disease control specific hot-water treatment regimes should be established for every particular gladiolus cultivar.