Plant Growth Suppression on Saline Media: Interactions with Light

Interactive effects of salinity and light on plant growth were studied with intact bean seedlings (Phaseolus vulgaris L.) and with excised cotyledonary leaves of radish (Raphanus sativus L.) cultured on control and saline (NaCl) media in the dark and under a range of light intensities. In both cases, excess NaCl had very little effect on heterotrophic growth in the dark; it had an unexpected stimulating effect on growth in low-intensity light and a suppressive effect only at moderately high light intensities. Excess NaCl was particularly effective in suppressing growth processes requiring high-energy light, for example, leaf expansion and the accompanying net synthesis of nucleic acid and protein. Microscopic examination and analysis of chloroplasts of salt-stunted bean and pea (Pisum sativum L) plants indicated a suppression of chloroplast development.