## 3 Results
### Acclimatisation of Japanese Hascap Clones to Ex Vitro Conditions  
During the acclimatisation stage, not all microplants resumed growth, and complete necrosis of plantlets was observed in many cases (Table 6, Figure 4A).  
There were significantly more dying plantlets, mostly in the J21 clone. Both clones formed calluses of similar size, but J21 developed roots twice as long as those of J13. Microplants from NF explants had larger calluses and shorter roots compared to those from ST explants. The explant type did not affect the number of dead plantlets (Table 6, Figure 4B). Cold treatment led to more plantlet necrosis and death but did not influence callus formation or root elongation. Chilled ST plantlets of both clones died more frequently. More cooled NF plantlets started growing compared to STs (Table 6, Figure 4C). Chilled J21 plantlets formed smaller calluses, while J13 plantlets from STs did not produce calluses, unlike NF plantlets. J21 roots were larger after cooling, but J13 NF plantlets developed weaker roots, regardless of chilling.  
Significant differences in growth, rooting and acclimatisation of plantlets of both clones subjected to cooling were found (Table 7). The elongation of shoots of clone J21 was more intense compared to that of clone J13. The development of new shoots was similar regardless of the clone. Microplants derived from NFs and STs produced shoots in the same number and of similar length. Only in the first measurement was a significantly more intense elongation of shoots of plants originating from an ST explant observed.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Clone**} & \multirow{2}{*}{**Explant Type**} & \multicolumn{2}{c}{**Number of Short**} & \multicolumn{2}{c}{**Number of Long**} & \multicolumn{2}{c}{**Total Number of**} & \multicolumn{2}{c}{**Length of the Longest**} \\  & & **Shoots (3–9 mm) [psc]** & **Shoots (\textgreater{}10 mm) [psc]** & **Shoots [pcs]** & **Shoot [cm]** \\ \hline \multirow{2}{*}{J21} & NF & 0.1 a \({}^{1}\) & 1.2 a & 1.2 a & 6.3 a \\ \cline{2-6}  & ST & 0.0 a & 1.0 a & 1.0 a & 6.9 a \\ \hline \multirow{2}{*}{J13} & NF & 0.0 a & 1.0 a & 1.0 a & 7.0 a \\ \cline{2-6}  & ST & 0.0 a & 1.0 a & 1.0 a & 6.5 a \\ \hline \multirow{2}{*}{SL \({}^{2}\)} & & ns & ns & ns & ns \\ \hline \(SL_{int}\)\({}^{3}\) & & ns & ns & ns & ns \\ \hline J21 & - & 0.0 a & 1.1 a & 1.1 a & 6.5 a \\ \hline J13 & - & 0.0 a & 1.0 a & 1.0 a & 6.6 a \\ \hline SL & & ns & ns & ns & ns \\ \hline - & NF & 0.1 a & 1.1 a & 1.2 a & 6.4 a \\ \hline - & ST & 0.0 a & 1.0 a & 1.0 a & 6.7 a \\ \hline SL & & ns & ns & ns & ns \\ \hline \end{tabular} \({}^{1}\) Different letters indicate significant differences among means at \(<0.05\). \({}^{2}\) SL—level of significance of differences among variables: ns—not significant.\({}^{3}\) SL\({}_{int}\)—level of significance for interaction: clone x type of explant.  
\end{table}
Table 5: Development of Japanese hascap clones in rooting stage of in vitro cultures established from different explants.  
A clone-specific reaction of previously used explants (NFs or STs) to cold storage was found in the case of plantlet growth (Slint-**), especially in the first weeks of acclimatisation. Microplants of clones J21 and J13 derived from NFs grew significantly better if they were not subjected to cooling. Plants of both clones originating from NFs responded to cooling by weakened shoot elongation in the first week of acclimation. The effect of cooling on shoot proliferation was not significant after the first week, except for plants of the J21 clone obtained from NFs. In this case, cooling weakened the development of side shoots during acclimation until the end of this study (Table 7).