Callus Age and Size of Barley (<i>Hordeum vulgare</i> L.) Improves Regeneration Efficiency

In order to improve regeneration efficiency embryos derived from immature seeds of BARI barley-6 were taken for this study. In this case callus size, age and its fresh weight were considered. Embryos sizes were classified into four groups: 0.6-1.0 mm (A), 1.1-1.5 mm (B), 1.6-2.0 mm (C) and 2.1-2.5 mm (D), and cultured to semi-solid MS medium for callus induction. Five weeks old calli were transferred to MS medium that contained 1.0 mg/l BAP + 150 mg/l L-glutamine, for regeneration. Results indicated that 1.6-2.0 mm size of embryos produced the highest callusing (56.72%) and green plantlets (42.16%), while small sized (0.6-1.0 mm) showed very poor (2.75%) callusing and no regeneration occurred. Calli were divided into three age groups e.g. early (1-3 weeks), medium (4-6 weeks) and prolonged age (7-12 weeks) and cultured to regeneration medium. To observe the effect of calli weight on regeneration, they were grouped into four categories: I (50-100 mg), II (101-150 mg), III (151-200 mg) and IV (>201 mg). The highest regeneration and rooting were recorded when the age of callus was 4-6 weeks and its weight range was 151–200 mg (III). The lowest regeneration and rooting were found when 1-3 weeks old calli were used and its average weight was 50-100 mg (I).