At the beginning of the micropropagation process, explants were extracted from the
plants grown in a greenhouse. They were 1–1.5 cm long and consisted of a stem node
with an axillary bud, fragments of internodes, and a fragment of petiole (fig. 1A). The
explants were disinfected in 0.1% HgCl2 solution for 7 minutes, rinsed in sterile water
and inserted in fours into 0.4 dm3 jars with agar-solidified medium. Each experimental
set consisted of 20 jars. The jars were placed in a growth chamber with a temperature of
25°C, photoperiod of 16/8 h, and white light with an intensity of 25–30 μmol m-2 s-1.
After 4 weeks, for each experimental set alive explants were calculated, plants with one
shot and this ones produced two shots. Later on, 40 plants from each set were examined
to determine the following features: weight and length of the shoot, number of internodes,
and number and weight of the roots. The remaining plants served as a source of
explants for the subculture. Those explants were much smaller than the primary; the
stem fragments were 2–3 mm long, while the petioles – approx. 1 cm long (fig. 1). Because
the induction of organogenesis in the subculture was delayed, the period of plant
regeneration was extended to 5 weeks. Then, were counted every living explants, sweet
potato plants and alive explants without shoots. 40 plants from each set were examined
to measure the same parameters as in the first culture. Forty plants were planted into
0.33 dm3 cylindrical plastic pots filled with a not-sterile mixture of horticultural soil and
sand (3:1) and subjected to hardening. The pots were covered with plastic covers and
placed in a greenhouse, where they were exposed to natural light and temperature fluctuations.
The covers were removed after two weeks. The plants were kept in an unheated
glasshouse for 4 weeks and then planted in the open field. Some of the plants (12 from each set) were left in jars and kept in a growth chamber. After 7 weeks from
the establishment of the culture, the length of their shoots was measured and the internodes
were counted.
The results were subjected to statistical analysis according to the completely randomised
2 × 2 factorial experiment design. The significance of differences between the
mean values of individual parameters was determined using the Tukey’s test.
At the beginning of the micropropagation process, explants were extracted from theplants grown in a greenhouse. They were 1–1.5 cm long and consisted of a stem nodewith an axillary bud, fragments of internodes, and a fragment of petiole (fig. 1A). Theexplants were disinfected in 0.1% HgCl2 solution for 7 minutes, rinsed in sterile waterand inserted in fours into 0.4 dm3 jars with agar-solidified medium. Each experimentalset consisted of 20 jars. The jars were placed in a growth chamber with a temperature of25°C, photoperiod of 16/8 h, and white light with an intensity of 25–30 μmol m-2 s-1.After 4 weeks, for each experimental set alive explants were calculated, plants with oneshot and this ones produced two shots. Later on, 40 plants from each set were examinedto determine the following features: weight and length of the shoot, number of internodes,and number and weight of the roots. The remaining plants served as a source ofexplants for the subculture. Those explants were much smaller than the primary; thestem fragments were 2–3 mm long, while the petioles – approx. 1 cm long (fig. 1). Becausethe induction of organogenesis in the subculture was delayed, the period of plantregeneration was extended to 5 weeks. Then, were counted every living explants, sweetpotato plants and alive explants without shoots. 40 plants from each set were examinedto measure the same parameters as in the first culture. Forty plants were planted into0.33 dm3 cylindrical plastic pots filled with a not-sterile mixture of horticultural soil andsand (3:1) and subjected to hardening. The pots were covered with plastic covers andplaced in a greenhouse, where they were exposed to natural light and temperature fluctuations.The covers were removed after two weeks. The plants were kept in an unheatedglasshouse for 4 weeks and then planted in the open field. Some of the plants (12 from each set) were left in jars and kept in a growth chamber. After 7 weeks fromthe establishment of the culture, the length of their shoots was measured and the internodeswere counted.The results were subjected to statistical analysis according to the completely randomised2 × 2 factorial experiment design. The significance of differences between themean values of individual parameters was determined using the Tukey’s test.
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