SALT STRESS AND SALT-TEMPERATURE INTERACTION EFFECTS ON THE GERMINATION OF <em>PELTOPHORUM</em> <em>DUBIUM</em> SEEDS

Abstract

Peltophorum dubium is a tree species native to the Brazilian semideciduous forest and considered a threatened species. A study was undertaken to determine its maximum tolerance limit to different salts (KC1, NaCI, CaCl₂) and the salt-temperature interactions at 24, 27 and 30 °C. Four replicates of 50 seeds were used for each treatment. Germination was carried out in sterilised Petri dishes covered with autoclaved filter paper moistened with salt solution or Captan (0.2%). Peltophorum dubium is a salt tolerant species, but the average germination rate and germinability decreased with decreasing osmotic potential. At 24, 27, 30 °C and for all osmotic potentials used, CaCl₂ was the most toxic, followed by KC1 and finally NaCI. An interaction between salt and temperature was registered. At 30 °C the maximum tolerance limit was reduced when KC1, NaCI and CaCl₂ solutions were added. When the incubation temperature was lowered (from 27 to 24 °C), the maximal tolerance limit was extended for NaCI and reduced for KC1 and CaCl₂ salt solutions.