In vitro morphogenesis of garlic plants: the role of growth regulators in bulb induction and development/ Morfogenese de plantas de alho in vitro: papel dos reguladores de crescimento na inducao e desenvolvimento de bulbos

Efficient protocols for garlic (Allium sativum L.) shoot tips growth and later in vitro bulbing are significant for pathogen removal and maintenance of genetic fidelity. The objective of this study was to assess the effects of different types and concentrations of growth regulators on in vitro morphogenesis of garlic plants. Shoot meristems with up to two primordial were excised from garlic bulbils (cv. 'Jonas') and cultivated in vitro in culture media supplemented with indoleacetic acid (0; 1,07; 2,69 e 5,37 [micro]M), indolbutyric acid (0; 0,49; 0,98 e 2,46 [micro]M), naphthaleneacetic acid (0; 1,07; 2,69 e 5,37 [micro]M), and abscisic acid (0; 0,38; 1,89; e 3,78 [micro]M). The concentration of 1,07 [micro]M indoleacetic acid applied to the culture medium promoted increases in most variables analyzed. Jasmonic acid induced formation of garlic bulbs in vitro, although it showed lower performance than that verified with the use of NAA. On the other hand, addition of abscisic acid in culture media inhibited plant growth. However, it did not impede the formation of bulbs, especially when in reduced concentrations. Generally speaking, variables such as number of bulbs and rate of bulbing decreased with the use of high concentrations of the assessed growth regulators. Among plant growth regulators, NAA showed a stronger effect on in vitro morphogenesis of garlic plants. Nonetheless, jasmonic acid and ABA also showed potential to induce formation of garlic bulbs in vitro such as NAA. Key words: micropropagation, shoot tips, bulbing, Allium sativum. Protocolos eficientes de crescimento de apices caulinares de alho (.Allium sativum L.) e posterior bulbificacao in vitro sao importantes para limpeza clonal e manutencao da fidelidade genetica. O trabalho teve como objetivo avaliar os efeitos de tipos e concentracoes de reguladores de crescimento sobre a morfogenese de plantas de alho in vitro. Apices caulinares com ate dois primordios foram excisados de bulbilhos de alho da cv 'Jonas ' e submetidos ao cultivo in vitro em meio de cultura suplementado de acido indolacetico (0; 1,07; 2,69 e 5,37 [micro]M), acido indolbutirico (0; 0,49; 0,98 e 2,46 [micro]M), acido naftalenoacetico (0; 1,07; 2,69 e 5,37 [micro]M), acido jasmonico (0; 1,0; 5,0 e 10,0 [micro]M) e acido abscisico (0; 0,38; 1,89; e 3,78 [micro]M). A concentracao de 1,07 [micro]M de acido naftalenoacetico aplicado ao meio de cultura promoveu incrementos na maioria das variaveis analisadas. O acido jasmonico