Changes in photosynthetic rate, water potential, and proline content in kenaf seedlings under salt stress

Abstract

Jin, C.-W., Sun, Y.-L. and Cho, D.-H. 2012. Changes in photosynthetic rate, water potential, and proline content in kenaf seedlings under salt stress. Can. J. Plant Sci. 92: 311–319. As irrigation water salinization has become a serious constraint for crop production, as well as soil salinity, the selection and use of salt-tolerant species is urgently required. In this study, we describe the salt responses of three kenaf (Hibiscus cannabinus L.) cultivars and select the cultivar with high salt tolerance. Responses to salt stress were investigated in terms of growth, water potentials, photosynthesis, and proline contents. Photosynthesis, evaluated by net CO2assimilation rate, stomatal conductance, and intercellular CO2concentration, did not show any significant effects among the cultivars. Leaf water potential decreased depending on salt concentration and salt treatment period. Proline accumulation was enhanced, particularly depending on salt concentration, but not salt treatment period. As salt concentration increased, seedling growth was inhibited to a certain extent, and the inhibition of growth depended mainly on salt concentration. At the early stage of treatment, Dowling was more tolerant to salt stress than Everglade-41 and Tainung-2. Although Dowling showed a lower decrease in fresh weight, Tainung-2 always maintained a relatively high vegetative yield, even under high salt stress. Tainung-2, having greater salt adaptation, was therefore considered an ideal cultivar for popularization and farm cultivation.