Direct differentiation of shoot buds in leaf segments of white marigold (Tagetes erecta L.)

A protocol has been developed for differentiation of shoot buds directly fr om leaf segments of white marigold (Tagetes erecta L.). Leaf segments were taken from in vitro-proliferated shoots of white marigold established in as eptic culture from shoot tips of field-grown plants. Gibberellic acid (GA) played a significant role in the induction of shoot buds as well as in supp ressing callus formation. Shoot buds were induced directly in Murashige and Skoog's (MS) medium supplemented with 14.43 muM GA and 4.44 muM 6-benzylad enine in the absence of any auxin. In this medium two to five shoot buds di fferentiated from the margins as well as leaf lamina of the lower petiolar segment within 4 wk of incubation. Differentiated shoots grew well and prol iferated in the MS medium having 1.1 muM BA and 29.41 muM AgNO3, as it had a beneficial effect on the growth and proliferation of shoots. Shoots were excised, rooted in 0.27 muM alpha- naphthaleneacetic acid (NAA) and transpl anted under glasshouse conditions, where they grew and flowered. Data on di fferent morphological characters during flowering under field conditions we re recorded for seed-grown control plants, tissue culture-raised primary re generants (R-0) and first-generation (R-1) plants. It was found that all th e economically desired characters of plant height, number and size of flowe rs per plant, number of viable seeds per flower, and days to full bloom, of the R-1 generation plants were significantly better than the control, thus increasing the commercial value of the tissue culture-raised plants in suc cessive generations.