| || || Palupe, Anthony.|
| || || The rapid multiplication of taro Colocasia esculenta L. Schott var. esculenta by in vitro shoot tip culture culture|
Institution: University of the South Pacific.
Subject: Taro -- Micropropagation, Taro -- Breeding, Taro -- Research -- Oceania
Call No.: pac SB 211 .T2 P34
Copyright:This thesis may NOT be copied without the authors written permission.
Abstract: The rapid multiplication of taro Colocasia esculenta var. esculenta using in vitro shoot tip culture has been studied. The taro multiplication system that has been in use in the regional laboratory in Western Samoa utilised a modified Murashige and Skoog medium known as 'E' medium. Sucker production was not optimised using this system and was varietal dependent. The effect on sucker production of increasing BAP and NAA levels in the basal culture medium was examined. Increasing BAP concentrations increased shoot production but also decreased plant height and inhibited root formation. Similarly, increasing NAA levels inhibited plant height and root formation, but did not increase shoot production. The addition of spermine to 'E' medium improved shoot production. 0.5 mg r1spermine initially gave high shoot numbers but on transfer to a medium lacking in spermine, cultures previously incubated on 1.0 mg 1" spermine had the highest number of shoots. The use of spermine in a liquid medium did not improve shoot production. The presence of TDZ in the culture medium successfully induced shoot initiation and inhibited plant height and root formation. The optimum TDZ concentration for shoot production was 0.025 mgI-1 . The initiated shoots were fasciated and cultures were hyperhydrated. The addition of NAA reduced shoot fasciation and culture hyperhydricity but also reduced shoot production. The presence of NAA also reduced the inhibitory effect of TDZ on root formation and plant height. The addition of BAP instead of NAA in combination with TDZ did not improve shoot production but increased the degree of shoot fasciation. Although shoots were initiated on TDZ containing medium, transfer to the secondary medium lacking TDZ but containing BAP (1.0 mg 1 ) was necessary to obtain maximum shoot development. Culture on a third medium containing TDZ (0.005 mgI-1) in isolation at a lower concentration than in the medium further increased shoot number. This three stage system is now recommended for maximizing shoot production with a potential of 11.4 million suckers per annum.