SURVIVAL AND GROWTH OF EASTERN WHITE-PINE SHOOT APICAL MERISTEMS IN-VITRO

Shoot apical meristems of seedling and mature eastern white pine trees were excised and grown in vitro. Placing the meristems on filters ins tead of directly on agarose-solidified nutrient medium enhanced surviv al of both juvenile and mature meristems. Applying forcing treatments to mature branches improved survival and growth of dissected meristems compared with meristems from non-forced branches in experiments condu cted over two years. No consistent differences were observed among 2-, 4-, and 6-week forcing treatments. Including 5.37 nM (0.001 mg 1(-1)) 1-naphthareneacetic acid in the culture medium did not affect meriste m survival or growth. Some meristems from seedlings grew rapidly, prod uced primary leaves, underwent internode elongation, and in three case s, produced adventitious roots. Meristems from mature trees did not gr ow as rapidly as seedling meristems. The leaves produced by mature mer istems appeared to be scale leaves and a few of these had brachyblast primordia in the axils. The shoots derived from mature meristems did n ot produce adventitious roots.