VOLUME 6 NUMBER 1 (January to June 2013)

by Fredeslinda C. Evangelista¹*, Rhodora R. Aldemita², and Lilian B. Ungson³

¹Department of Biology, University of the Philippines Manila, Padre Faura, Taft Avenue, Manila
²Philippine Rice Research Institute, Maligaya Munoz, Nueva Ecija
³Institute of Biology, University of the Philippines Diliman, Diliman, Quezon City

Saline soil is a major problem that affects growth andyield of rice, the staple food in the Philippines;hence, there is a need to develop a local variety thatcan thrive under this condition for sustainableproduction. The goal of the study is to obtainbaseline information regarding the responses of rice (Oryzasativa line LX278) calli and seedlings to salt. This is importantprior to genetic transformation so that any improvement ingrowth performance, after transformation, could be attributed tothe introduced salinity tolerance gene. Results showed that themean fresh weight of LX278 rice calli exposed to variousconcentrations of NaCl, ranging from 50mM to 175mM,significantly decreased as the concentrations of NaCl increasedcompared to the control. Prolonged exposure of up to a monthwith 150 mM NaCl and 175mM NaCl restricted and inhibited,respectively, the growth of calli. Two-way ANOVA (analysis ofvariance) showed that the effect of the interaction of saltconcentration and the duration of exposure on mean fresh weightof calli was highly significant. Meanwhile, LX278 rice seedlingsin hydroponics, exposed to NaCl of EC=12 dSm^-1, exhibited asalt sensitive response, relative to Pokkali, the tolerant control,and IR 29, the highly susceptible control, 16 days after initialsalinization using the rating system based on visual symptoms ofsalt toxicity. Results of the present study agree with earlierfindings that rice tolerates salinities of up to 30mM ~ 3dS m^-1and, beyond this, growth is compromised because of osmoticand ionic effects.