IRRIGATION TIMING—ITS INFLUENCE ON THE EFFECTS OF SALINITY AND WATERLOGGING STRESSES IN TOBACCO PLANTS

Publisher Website
Google Scholar
Abstract
Salinity (NaCl) and soil-oxygen-deficiency stresses were applied to tobacco [Nicotiana tabacum] plants, and water uptake by the plants was measured for 10 days. After 10 days Na+ and Cl- concentrations were measured in different plant parts. The plants were irrigated at 8 a.m. or 8 p.m. with or without salinity stress (90 me/l), and were allowed to drain or remain undrained (soil oxygen deficiency). Water uptake was significantly reduced (P = 0.05) by the presence of NaCl in the root zone irrespective of irrigation and drainage treatment. Leaf chloride in all nonsalinized treatments was significantly lower (P = 0.01) than in all salinized treatments. Both day and night waterlogged saline treatments were significantly higher (P = 0.01 and P = 0.05, respectively) than the nonwaterlogged salinized treatment. Thus, there was a strong and adverse effect of waterlogging on the uptake of NaCl. The saline treatment that was waterlogged at night was significantly lower (P = 0.05) than the day waterlogged saline treatment. This difference in Cl- concentration between day and night waterlogging treatments was significant only for leaf chloride, although the same trend to higher Cl- content with day waterlogging was present with petioles and stems. Root Cl- concentrations were relatively low irrespective of treatment. Leaf Na concentrations of day and night waterlogged salinity treatments were significantly higher (P = 0.01) than all other treatments, and the day waterlogged salinized plants were significantly higher (P = 0.05) in leaf Na+ than the night waterlogged salinity treatment. With respect to irrigation management, plants in a soil with some chance of being waterlogged even partially in the root zone and with NaCl present in the root zone would benefit from being irrigated at night rather than during the day.