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Axillary buds from 5-month-old seedlings of Azadirachta excelsa Linn. were surface-sterilized twice with 1.35% (m/v) and 1.05% (m/v) of sodium hypochlorite for 25 and 15 minutes, respectively, before culturing on Murashige and Skoog (MS) medium containing combinations of BA and NAA. A combination of 4.4 μM BA + 0.5 μM NAA induced the most axillary buds to grow (eight per explant). Subsequent proliferation of the micropropagated shoots on this medium yielded abnormal shoots. The best medium for maximum proliferation of these micropropagated shoots contained 3.3 μM BA and 0.27 μM NAA. On this medium about four normal shoots were produced per explant. These findings indicate that two different media are needed for successful micropropagation of sentang. Chemical names used: N 6-benzylaminopurine (BA); 1-naphthaleneacetic acid (NAA).
The effect of ethylene on tuber sprout growth and quality in potato (Solanum tuberosum L. `Russet Burbank') was tested in laboratory and commercial studies for 6 and 3 years, respectively, in comparison with untreated (laboratory study) and CIPC-treated tubers (laboratory and commercial studies). In both studies, ethylene was applied continuously at 166 μmol·m-3 for at least 25 weeks, beginning in early December (laboratory study) or early December to early January (commercial study). In the laboratory study, ethylene delayed the appearance of sprouts for 5 to 15 weeks, compared with untreated tubers. In the ethylene-treated tubers in both studies, sprouts appeared on many eyes but most of them remained very small (<5 mm long). Longer sprouts (>5 mm) appeared after 15 weeks but did not exceed 12 and 59 mm in the laboratory and commercial studies, respectively. Sprouts on ethylene-treated tubers were more easily detached up to 6 weeks after ethylene treatment ended, compared with untreated tubers. In both studies, ethylene treatment was not associated with decay, disorder or internal sprouting problems. In both studies, the Agtron fry color [or U.S. Dept. of Agriculture (USDA) color grade] of ethylene-treated tubers was darker than CIPC-treated tubers at almost all sampling times. Continuous exposure to ethylene was an effective sprout control agent but it produced a darker fry color, compared with CIPC-treated potatoes.