Sand culture technique was employed to investigate the effect of soil salinity and kinetin on chlorophyll a and b contents, the a/b ratio and the chlorophyll stability to heat in Sorghum bicolor and Gossypium barbadense cultivars. Levels of osmotic potential of the soil solution between -3 and -13 bar were adjusted by irrigation
with certain amounts of saline solutions containing NaCI and CaCI2. Kinetin solutions
(10 ppm) were applied by 3 methods: treatment of the seeds (presoaking), shoot
treatment (spraying) and by irrigation. Kinetin can retain the chlorophyll content and
even increases them in the two investigated plants when applied by presoaking method. The a : b ratio seems to be affected by salinity stress rather than by kinetin treatment. Kinetin enhances significantly the stability index of both chlorophyll types in particular when applied by presoaking method. The results proved that kinetin can alleviate salinity stress on chlorophyll parameters in both investigated
plants when applied by presoaking method rather than by the other methods