In vitro tuberization in genotypes of cassava.

The objective of this research was to induce in vitro tuberization in two cassava genotypes grown in liquid media with addition of 6-bezylaminopurine (BAP) and α-naphthaleneacetic acid (NAA) in different concentration of sucrose. Nodal segments (3 cm height) from the cultivars Mantiqueira and Parazinha were used as explants and kept in vitro MS media containing also mio-inositol (100 mg L-1) and sucrose (30 g L-1). The pH of the media was adjusted to 5.7 ± 0.1 before autoclaving. The root inducing media was composed by MS media plus 30 g L-1 sucrose (T1), MS plus 0.4 μM BAP + 1.6 μM NAA, in different concentrations of sucrose including 30 (T2), 60 (T3) and 80 g L-1 (T4), and MS media supplemented with 22 μM BAP, grown in 30 (T5), 60 (T6), 80 g L-1 sucrose (T7). The experiments were undertaken at 50 to 60 μmol light irradiance for eight hours at 27 ± 1oC. Number, length and pattern of the induced tuber roots were recorded. The length and number of roots were higher for T1, especially in Mantiqueira, but no formation of tuberous roots was observed. Tuber roots was observed after using T4 in both cultivars. Resumo O presente trabalho teve como objetivo a inducao in vitro de raizes tuberiformes de dois genotipos de mandioca cultivadas em meio liquido, sob a acao de 6-benzilaminopurina (BAP) e acido α-naftalenoacetico (ANA), e diferentes concentracoes de sacarose. Como explantes foram utilizados segmentos nodais, com cerca de 3 cm de comprimento, excisados de plantas de mandioca das cultivares Mantiqueira e Parazinha, mantidas in vitro mediante subcultivos em meio constituido dos sais de MS, mio-inositol (100 mg L-1) e sacarose (30 g L-1). O pH dos meios foi corrigido para 5,7