Response of Tomato (Lycopersicon esculentum Mill.) to in vitro Landuced Water Deficit
2000
Abu Shama, M.M
Water deficit is considered one of the most detrimental factors that controls plant growth and development in arid and semiarid areas. Effect of water deficit upon vegetative growth of tomato (Lycopersicon esculentum Mill.), "c.v. Rohaba" was investigated in vitro. Water deficit was applied in vitro by using (0.1, 0.2, 0.3, 0.4 M) of sucrose, or (0, 0.1, 0.2, 0.3 M) sorbitol or mannitol as an osmotic agents (all sorbitol and mannitol treatments contained sucrose (30 g/L)). In the sucrose experiment shoot height, and shoot fresh weight were significantly reduced at 0.4 M. Significant increase in shoot dry weight was obtained when sucrose levels were increased, while rooting % and root number were not significantly effected with different sucrose levels, root length was significantly increased at 0.3 M, and reduced at 0.4 M. im the case or sorbitol, shoot height was significantly reduced at 0.3 M. Shoot fresh weight and dry weight were significantly reduced as sorbitol levels were increased in the media . rooting %, root number, and root length were not-significantly affected at all sorbitol levels. For the mannitol experiment, shoot height was significantly increased at 0.1 M, whereas it was significantly reduced at 0.2 M amd 0.3M . Shoot dry weight and fresh weight were reduced as mannitol levels were . Rooting % and root number were enhanced at 0.1 M. Root length was increased in response to different mannitol levels. The osmotic potential of tomato microshoots was significantly reduced (become more negative) as sucrose, sorbitol, or mannitol levels were increased. Tomato microshoots contents of N, K, Mg, Na, and ash % were reduced significantly in response to increased levels of sucrose, sorbitol, or mannitol. Ca and P contents were not affected by elevated concentrations of osmoticum. Fiber content of tomato microshoots was not significantly affected at all sucrose levels, but a significant reduction in fiber content was obtained as sorbitol and mannitol levels were increased. Reducing sugar %, and carbohydrate %, and proline accumulation were increased, and the protein (crude and soluble protein), and fat contents were reduced as levels of sucrose, sorbitol, and mannitol were increased, which might indicate some tolerance of Rohaba tomato to in vitro induced water deficit through osmotic adjustment.
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