English

Abstract

Aseptic cultures of pineapple ‘smooth cayenne’ were established from shoot tip explants. They were initiated on Murashige and Skoog (MS) basal medium with vitamins supplemented with various combinations of 6-benzylaminopurine (BAP) (0, 0.1, 0.2, 0.3 and 0.4 mg L-1) and Gelrite [1.0 g L-1 (semi-liquid), 1.5 g L-1 (semi-solid) and 2.0 g L-1 (solid)]. Explants were transferred five weeks after in vitro initiation to semi-liquid medium containing higher concentrations of BAP (0, 0.5, 1.0, 1.5 and 2.0 mg L-1) for proliferation. Four sub-cultures were made at five weeks interval for twenty weeks in the proliferation medium. Established shoots were introduced into rooting medium containing either full (4.4 g L-1) or half (2.2 g L-1) strength MS basal medium with vitamins supplemented with 0, 0.5 mg L-1 BAP alone or in combination with 0, 0.9 and 1.8 mg L-1 α-naphthaleneacetic acid (NAA). Semi-liquid MS basal medium supplemented with 0.1 and 0.3 mg L-1 BAP gave the best regeneration results, producing the highest average shoot length (34.6 mm) and average number of shoot buds (2.4) per explants. Significant difference (p≤0.05) in average shoot number per explant was observed with semi-liquid MS basal medium supplemented with 1.5 mg L-1 BAP, producing the highest average shoot number (6.1) per explant at 5 weeks and this increased to 167.7 after 20 weeks. The half-strength MS basal medium without growth regulators or with 0.9 mg L-1 NAA gave the highest average root length (29.3 mm) and root number per shoot (7.9). The semi-liquid MS basal medium supplemented with low BAP (1.5 mg L-1) is a cost-effective method for in vitro propagation of pineapple. Half strength MS basal medium without hormones or with low NAA are also cost-effective methods for inducing roots in pineapple.   Key words: Gelrite, growth regulators, medium type, pineapple, propagation.