Acta Univ Latv (2004) 676: 173–176

Micropropagation of onion (Allium cepa L.)

Abstract

Bulblet formation, dormancy of plantlets, vitrification of tissue and decreasing regeneration ability are the main factors limiting the efficiency of onion micropropagation. The aim of the study was experimental micropropagation of onion cvs. 'Lietuvos didieji', 'Stutgarten Riesen' and 'Centurion' F1. Onions after desinfection were split radially into four equal sectors and cross-section. Murashige and Skoog medium, supplemented with 1 mg l-1 naphthaleneacetic acid, 0.9, 4.4, 8.9, 13.1 μM concentrations of 6-benzylaminopurine (BAP), kinetin (1.1, 5.3, 10.6, 5.8 μM) and 30 g l-1 sucrose were used for plant micropropagation. The efficiency for onion micropropagation of the investigated cultivars and type of an explant was assessed according to the ability of explants to regenerate microshoots. The highest number of microshoots (1.8 to 2.4 microshoots per explant) were formed by 'Centurion' F1 and 'Lietuvos didieji' explants, containing stem dome plus basal plate. Experiments with growth regulators showed that the number of microshoots increased when the BAP concentration was raised from 0.9 to 4.4 μM, respectively from 1.0 to 2.1 microshoots per explant. The lower concentration of BAP had a higher efficiency while raised BAP concentration significantly decreased regeneration. The highest micropropagation frequency using kinetin (1.9 to 2.1 microshoots per explant) was obtained at a moderate (10.6 μM) concentration. The regeneration intensity (output of microshoots) was 68 % higher using kinetin in comparison with BAP.