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NARCISSUS BULB MORPHOLOGY AND TWIN-SCALE PROPAGATION
Twin-scales were prepared, noting the generation (1st, 2nd or 3rd year) and origin (bulb scale, leaf base or flower scape) of the two scale-pieces.
After incubation at 20°C for 12 weeks, bulbil production was highest on propagules consisting of a 3rd year leaf base plus a 2nd year bulb scale; other types performed well, except those with 3rd or 1st year bulb scales or those including a scape.
Bulbil production was followed during prolonged incubation of twin-scales cut from the outermost position (A) through to the innermost position (E). Twin-scales of position A soon produced visible bulbil initials (mean, 6.4 weeks), but their period of bulbil growth was limited (13.5 weeks) and the bulbils obtained were small (113mm3). Progressively more central propagules produced bulbils later but these had an extended growing period and became larger (corresponding values for position E: 12.7 weeks, 33.2 weeks, 366mm3).
To attempt to modify bulbil production under a standard 12-week incubation, twin-scales were cut after 0–10 weeks of prior bulb storage at 5–30°C, and twin-scales were incubated with gibberellic acid (GA3) (100 ppm) or ancymidol (1–10 ppm). Bulbil production was maximal in positions B and C, decreasing in the inner twin-scales, and was minimal in position A. In general, bulbil production decreased with delayed cutting.
There was little effect of pre-cutting storage temperature, although the highest numbers and sizes of bulbils were obtained after prior 30°C-storage.
Bulbil production was reduced by GA3, but little affected by ancymidol.