Rose, A.M.; Raju, P.S.; Ahmad, Mohammed H.
The effect of varying auxin and cytokinin levels on in vitro rooting of yam, dioscorea cayenensis [Abstract]
Proceedings of the Second Conference of the Faculty of Natural Sciences University of the West Indies, Mona edited by Ralph D. Robinson, and Han Reichgelt.
Date of Meeting
March 7-9, 1995
Place of Meeting
University of the West Indies, Mona, Kingston, Jamaica
Place of Publication
Faculty of Natural Sciences, University of the West Indies, Mona.
Date of Publication
Date of Copyright
Location in Work
Extent of Work
Series Editor Role
Series Volume ID
Optimization of in vitro root growth in tissue culture yam plantlets is important to ensure successful hardening and optimum growth on transfer to the field. Dioscorea cayenensis cv. Roynd Leaf Yellow Yam was maintained on basal media containing Murashige and Skoog (MS) salts, 30 g sucrose, and 2 g phytagel L-1 supplemented with 0.1 mg 6-benzylaminopurine (BAP). After 4 weeks, plants having 2-4 nodes were subdivided to give cuttings, each consisting of a node and a leaf. The cuttings were subcultured for 6 weeks on basal media containing the following hormone supplements: indole-3-acetic acid at 0.002, 0.01, 0.05 and 0.25 mg L-1, indole-3-butyric acid at 0.002, 0.01, 0.05 and 0.25 mg L-1, naphthaleneacetic acid at 0.0002, 0.001, 0.005, and 0.025 mg L-1 and BAP at 0.02, 0.1 and 0.5 mg L-1. Basal medium with no hormone supplement served as the control. BAP at 0.1 and 0.5 mg L-1 inhibited root initiation and at 0.5 mg L-1 inhibited root elongation. Addition of an auxin to the basal medium did not enhance either root initiation or elongation and the endogenous levels of auxin appeared to be adequate for root initiation and elongation. Nodes from the base gave the best rooting with greater numbers and lengths of roots. Nodes further away from the basal node showed decreased rooting. The auxin synthesized in the shoot meristems moves basipetally, therefore, its concentration in tissues is expected to decrease with distance away from the shoot apex. It appeared that the low concentration of endogeneous auxin found at the basal node stimulated rooting, whereas the higher auxin concentrations found in the upper nodes inhibited rooting.....