Abstract:
The Philippines has rich soil suitable for agriculture but intrusion of salts into rice lands greatly reduce crop yield. Mestizo 55, a new variety released by Philippine Rice Research Institute (PhilRice) is nationally recommended for irrigated lowlands, where salinity stress is a possible risk. The present study provides the first detailed evaluation on the salinity tolerance rating of Mestizo 55 and the alleviating effect of ABA pretreatment on Mestizo 55 rice grown in 12 dS/m NaCl solution. Modified glass plate method was used to evaluate growth performance of germinating seeds while modified hydroponics system was used to assess the salinity tolerance score and growth performance of 2-3 leaf seedlings. Visual scoring showed that Mestizo 55 is highly salt susceptible. A 10-5 M ABA pretreatment was shown to have an alleviating effect on stressed germinating seeds. The ABA concentrations used for pretreatment had no alleviating effect on seedlings at 2-3 leaf stage, though, growth parameters were seen to increase from 10-4 to 10-6 M. Concentrations less than 10-6 M are recommended for further study of the alleviating effects of ABA at 2-3 leaf seedling stage. Abscisic acid (ABA), 2-3 leaf stage, germination stage, Mestizo 55, salinity tolerance, NaCl stress alleviation, hypersalinity.
