Salt and drought stress in wheat and the role of abscisic acid

The effects of different concentrations (150 mM and 300 mM) of NaCl alone or in combination with drought stress were determined on six wheat varieties. Among them, four viz. E-38, E-37, E-2 and E-30 were newly released, whereas Lu-26 and Pasban-90 were commercial varieties. The plants were grown in pots under natural conditions with protective measures against rain. Drought was induced for 7d to salt stressed plants at three-leaf stage by withholding the supply of salt/water (in case of control). The response of salt and drought were studied on growth parameters and yield of wheat. The proline contents of leaves and the concentration of abscisic acid and giberrellic acid were also measured at three leaf stage. The increasing concentration of NaCl had a significant inhibitory effect on the growth parameters. Relatively sensitive varieties i.e. Pasban-90 and E-38 were markedly affected, whereas, the relatively tolerant varieties Lu-26 and E-30 were the least affected by either concentration of NaCl and performed better with respect to both yield parameters and biochemical characteristics. The combined effect of salt and drought was more inhibitory than salt alone. Both the proline and ABA contents were greater in Lu-26 and in E-30 treated with 300 mM NaCl. The role of ABA and proline in salt and drought stress has been discussed.