Effects of simulated acid rain on germination and growth of rice plant

Two separate experiments were conducted in the glasshouse at MARDI, Serdang, to assess the effects of simulated acid rain on germination and growth of rice plant cv MR 84. In the first experiment, rice seeds were exposed to simulated acid rain acidified to pH 3.5, 4.0, 4.5, 5.0 and 5.6 (control) everyday for 2 weeks. Percentage of germination was determined from 7 to 19 days after sowing. In the second experiment, rice seedlings were exposed to similar simulated acid rain for every 2 days starting from 7 days after transplanting. The plants received approximately 20 mm of rain for each application. Growth parameters such as plant height, tiller and leaf number were measured from 15 days after transplanting until harvest. The results showed that germination, tiller and leaf number were reduced significantly by simulated acid rain particularly at pH 3.5. Relative to pH 5.6 (control), maximum germination percentage, tiller number and leaf number were reduced about 4, 14 and 10% respectively. Meanwhile, plant height showed no significant reduction at any pH level.