Abstract. Leaves taken from micropropagated shoots of several apple (Malus domesticaBorkh.) cultivars were cultured in vitro on Linsmaier & Skoog (LS) medium or the rice anther culture medium of Chu et al. (N6) containing various concentrations of either benzyladenine (BA) or thidiazuron (TDZ) plus naphthaleneacetic acid (NAA). Of the TDZ concentrations tested, 10/~M was most effective and it was equivalent to, or better than, 22~M BA for both the percentage of leaves regenerating shoots and number of shoots formed per regenerating leaf in almost every experiment. Lower concentrations of NAA (1.1 and 5.4/zM) gave best results with both BA and TDZ. N6 medium gave consistently better results than LS. Lowering total salt concentration or total N concentration of LS to that of N6 did not improve the response nor did changing the NO3:NH4 ratio. The 3-4 leaves on the most distal part of the shoot were most responsive and tended to form the most adventitious shoots. Placing the leaf cultures in the dark for the first 2-3 weeks of the culture period produced the best results. Optimum results were obtained by culturing leaves from the distal part of the shoot in the dark for 2 weeks on N6 medium containing 10#M TDZ and 1.1 or 5.4/zM NAA, then moving the cultures to 16 h daylight at a photon flux of 60pmol s ~m -~.

Shoot tips of 'York' and 'Vermont Spur Delicious' apples (Malus domestica Borkh.) were cultured in vitro to test the influence of K + , Mg + + and gelling agent concentrations on vitrification. These concentrations were 20.05, 14.05 and 8.05 mM K + , 1.5 and 3.0 mM Mg ~ +, 7.0 g/1 Difco Bacto agar and 1.0, 1.5 and 2.0 g/1 Gelrite. The lowest K + level produced a higher percentage of vitrified shoots, affected tissue appearance, reduced shoot number and shoot elongation and apparently altered shoot metabolic activity. Gelrite consistently produced vitrified leaves and stems, even though media gelled with 1.5 g/1 Gelrite presented the same apparent gel firmness as using 7 g/1 Difco Bacto agar, which did not induce vitrification. Less shoot elongation, fewer total shoots, and more usable shoots of 'York' were obtained on Bacto-agar, while similar but less noticeable effects were obtained with 'Vermont Spur Delicious'. The results presented here show that vitrification can be studied in a standardized system in which the only change is substitution of one gelling agent for another.

Autumn olive (Elaeagnus umbellata Thunb.) has edible fruit with brilliant red or yellow pigmentation. An analysis of the pigment in fruit of five cultivars and six naturalized plants showed that the berries contain lycopene, α-cryptoxanthin, β-cryptoxanthin, β-carotene, lutein, phytoene, and phytofluene. The lycopene content per 100 g ranged from 15 to 54 mg in fresh fruit from the naturalized plants and from 17 to 48 mg in the four cultivars with red-pigmented fruit. A cultivar with yellow fruit had only 0.47 mg/100 g fresh fruit. In contrast, fresh tomato fruit, the major dietary source of lycopene, has a lycopene content per 100 g of ≈3 mg. This newly identified source of lycopene may provide an alternative to tomato as a dietary source of lycopene and related carotenoids.