Axillary buds of Three cultivars of Morus alba Spp., Kokoso (KO), Iljiros (IL) and Moritiana (MO) were tested for their tolerance to salt and drought stress in vitro. Survival % for MO cv. reached 60 % under 7.5 gl-1 NaCl and 4 weeks exposure, while it was 13.3 % after 6 weeks. The highest original shoot length under1.5 gl-1 salt and 4 weeks exposure was for MO cv.. KO continued to tolerate up till 7.5 gl-1 NaCl after 6 weeks exposure by continuous leaves production. The highest significant number of injured leaves was recorded for IL at 1.5 gl-1 salt after the 6 weeks exposure. The higher bud burst 100 % has significantly took place at zero and 1.5 gl-1 salt level for MO cv. and decreased afterwards till it reached 20 % at 7.5 gl-1 NaCl level. The highest average number of proliferated shoot length was (2.5 shoot/explant) for MO cv. at 1.5 gl-1 NaCl followed by KO cv. (2.25 shoot/explant) at 2.5 gl-1 NaCl and the lowest value was recorded at 1.5 gl-1 NaCl (0.25 shoot/explant) for ILcv.. While, the highest proliferated shoot length was recorded for KO cv. (8.25, 7.63 mm) at salinity level of 1.5 and 2.5 gl-1 NaCl level, respectively. Proline accumulated significantly and rapidly for IL under salt levels from 1.5-7.5 gl-1 reached the highest content at 7.5 gl-1. Regarding PEG effect, at 40 gl-1 and after 4 weeks exposure, MO recorded significant highest survival (36.6 %) compared to the other cvs. and other exposure times. It observed that, KO cv. was able to grow for 4 and 6 weeks exposure even under 60 gl-1 PEG. Beyond 40 gl-1 PEG the number of leaves decreased significantly for MO and IL after 4 and 6 weeks where none of them survived. While KO cv still produce leaves in a lower insignificant rate. The KO cv. at 0.0 gl-1 PEG suffered from necrosis after 6 weeks culture and the number of injured leaves was (0.73) which insignificantly differed from MO cv. (0.85) but at high PEG (40 gl-1). Also, The MO cv. achieved high significant bud burst at 10 gl-1 PEG and decreased significantly at 40 gl-1 then stopped completely beyond. The lowest number of proliferated shoots was recorded for KO and MO (0.25) at 20 and 40 gl-1 PEG, respectively. The three cultivars showed insignificantly differences in proliferated shoot length. Under 20 gl-1 PEG, proline content for three cvs. was significantly higher than the control and 10 gl-1 PEG. Also, KO and MO were insignificantly higher than IL.
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