NACL-INDUCED AND GIBBERELLIC ACID-INDUCED CHANGES IN THE CONTENT OF AUXIN AND THE ACTIVITIES OF CELLULASE AND PECTIN LYASE DURING LEAF GROWTH IN RICE (ORYZA-SATIVA)

The interactive effect of NaCl salinity and gibberellic acid in the activities of cellulase and pectin lyase, and on the content of auxin and chlorophyll, has been determined during leaf growth (fifth from base) in rice. The linear growth, chlorophyll content, activity of cellulase, and the auxin level of leaves were markedly decreased when plants were exposed to salt stress (12 dS m-1). However pectin lyase activity did not register any significant alteration in the leaves of salt-stressed plants compared with the control. Treatment of plants with gibberellic acid (GA3) (10 ppm) increased the leaf growth and chlorophyll content with a concomitant rise in the activity of cellulase under stressed as well as non-stressed conditions. A marked increase in the content of auxin was discernible in the leaves of salt-stressed plants treated with GA3 compared with non-treated salinized ones. An appreciable increment in the activity of pectin lyase in response to GA3 administration was detected only in the leaves of non-stressed plants. These results indicate that enhancement of cellulase activity and the augmentation of endogenous auxin content may be involved in the stimulation of rice leaf growth by GA3 under saline conditions. © 1990 Annals of Botany Company.