Aseptic cultures of banana cultivars (evs) Maghraby (Mg). Valery (V). Grand
Nain (GN) and Hindy (H) were estabUshed from snoot tip explants, They were initiated
on M5-basal medium supplemented with 3 mgll benzyl adenine (SA) and 6 gl1 agar
(starting medium). Explants were transferred at 4 week intervals until the onset of
prolireration (about 2 months). Thereafter, 4 subcuttures were made on multiplication
medium containing SA (5 mgJI). The produced shoots were used to evaluate lhe in
vitro reseonses of tested cultivars to water (osmotic) atress induced by PEG with
respect to the type at medium. Shoot survival was gradually delayed by Ihe elevated
levels of PEG e 15 gJI). but the response was more pronounced in Mg and V than GN
followed by H. Applying PEG (10 and 20 gl1) to the medium progressively reduced the
in vitro growth and development of shoots. but the magnitude of this reduction was
more evident in case ofV and Mg than GN followed by H. However, the root growth
and development showed a conlrary trend under the effect of PEG, but a similar
response under the effect of cultivar. AI 2 % PEG, medium liquefaction improved the
growth and development of bolh shoots and roots. Moreover, the cultivar H achieved
the highest values of Ihese characters, whereas V and Mg had the lowest ones. It was
found that, the accumulation of lolal soluble sugars (TSS) and proline in shools was
pOSItively correlated wIth waler stress induced by PEG and agar, while Ihe reverse
was true in case of N. P and K accumulation. Furthermore. the metabolite
accumulation (N. P, K. TSS and Proline) in shoots of PEG-treated media was superior
in the cultivar H and inferior in Mg, Therefore. it was deduced that: (1) the cultivar H is
the most tolerant to water stress, (2) although, Ihe cultlvars GN, V and Mg did not
survive al 4.5% r;NN) PEG, the cultivar GN appeared to be more tolerant than V and
Mg, and (3) the higher levels of metabolite accumulation, especially proline end TSS,
enhance the plant tolerance to water stress.