I nt. J. Sustain. Crop Prod. 2(3) (August 2007) 17 BIOCHEMICAL ATTRIBUTES OF MUTANT RICE UNDER DIFFERENT SALINE LEVELS M. Z .ISLAM 1 , M. A. BASET MIA 2 , A. AKTER 3 AND M. H. RAHMAN 4 1 SO, Genetic Resources and Seed Division , Bangladesh Rice Research Institute (BRRI), Gazipur, 2 Associate Professor , Department of Crop Botany, Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur, 3 SO, Spices Research Centre, Bangladesh Agricultural Research Institute (BARI) , Bogra, 4 SO, Hybrid Rice Project, BRRI, Gazipur, Bangladesh Accepted for publication: 07 Jun, 2007 ABSTRACT Islam, M.Z., Baset Mia, M.A., Akter, A. and Rahman, M.H. 2007. Biochemical Attributes of Mutant Rice under Different Saline Levels. Int. J. Sustain. Crop Prod. 2(3):17-21 A pot experiment was conducted at the Bangladesh Institute of Nuclear Agriculture (BINA), Mymensingh to find out the biochemical attributes of mutant rice under varied saline levels during T-aman season from July to November 2003. Three rice genotypes viz. Q-31, Y-1281, and MR-219 were used as tests materials. The experiment was laid out in a Randomized Complete Block Design (RCBD) with four replications. Six salinity levels namely 15 dSm -1 , 12 dSm -1 , 9 dSm -1 , 6 dSm -1 , 3 dSm -1 with a control were imposed in this experiment. Results of the experiments clearly showed that biochemical characters such as total chlorophyll content, nitrate reductase activity, K + and Ca ++ etc. content of straw were reduced with increase levels of salinity compared to control. On the other hand, Na + were increased with increasing salinity levels. Among the genotypes, MR-219 showed best performance in respect of salt tolerant up to 6 dSm -1 and showed Y-1281 intermediate status. The genotypes Q-31 and Y-1281 showed its susceptibility to salinity stress. Key words: salinity stress, biochemical attributes and mutant rice INTRODUCTION Rice provides food and livelihood security Bangladesh, where it is the principal food of the people. But the yield of rice in Bangladesh is much lower than that of rice in other rice growing countries of the world. Among the various factors limiting rice yield, salinity is one of the oldest and most serious environmental problems in the world (Mcwilliam, 1986). In Bangladesh, over thirty percent of the net cultivable area is in the coastal area. Out of 2.85 million hectare of the coastal and off-shore areas, about 0.833 million hectares are arable lands, which constitute about 52.8 percent of the net cultivable area in 64 thanas of 13 districts (Karim et al., 1990). This area is largely affected by varying degrees of salinity and decreased the agricultural productivity seriously. As reclamation of saline soils is laborious and almost impossible, development or selection of salt tolerant crop species is one of the possible means for extension of crop area. Generally, salinity affects the growth of rice plant at all stages of its life cycle. But it is more pronounced on reproductive stage than on vegetative stage consequently decreased the grain yield (Afridi et al., 1988). Rice is moderately susceptible to salinity, since most rice plants are severely injured at an EC 8-10 dSm -1 . Study on the response of rice to salinity stress may be helpful in breeding salt tolerant cultivars by identifying physiological features potential salinity tolerance such as active osmotic adjustment in cells sap, accumulation of toxic Na + and Cl - ions in the older parts of the plant, higher photosynthetic efficiency of the young leaves, escaping ability to uptake Na + and Cl - etc. (Sultana et al., 2002 ) showed that the Na + concentrations of leaf is increased, while Ca ++ and K + concentrations of leaf is decreased with increasing of salinity level. It is generally recognized that K + uptake by the plant and deposition in both growing and non-growing tissues is reduced by salinization. Many studies conducted with reasonable Na:Ca ratios in the solutions have suggested that Ca +2 uptake, translocation and distribution may be critically affected by salinization. Salt tolerant cultivars had lower Na and higher K content (Won et al., 1992). The effect of soil salinity varies from variety to variety. Yield losses due to salinity are amounted to 30-50 percent. Our farmers normally grow local varieties due to unavailability of salt tolerant high yielding varieties (HYV). Therefore, to keep pace with the population growth and food productions, the yield per unit area needs to be increased for minimizing the yield gap. Grain yield decreased with increasing salinity levels. Appropriate salt tolerant high yielding varieties that can fit into the rice-growing ecosystem in the coastal areas of Bangladesh will boost up the country's rice production. Therefore, the present research work was undertaken to estimate the biochemical attributes (total chlorophyll content, nitrate reductase activity, Na + , K + and Ca + ) of mutant rice under different saline levels. MATERIALS AND METHODS A pot culture experiment was carried out in Bangladesh Institute of Nuclear Agriculture (BINA) of which each pot contained 8.0 kg of dried soil, belongs to the Sonatola series of Grey Flood Plain under the Old Brahmaputra Agro-Ecological Zone (UNDP and FAO, 1988). The p H value, cation exchange capacity (CEC) and electrical conductivity (EC) of the soil were 6.44, 6.78meq/100 g soil and 0.6 dSm -1 respectively. Three rice genotypes Q- 31, Y-1281 and MR-219 were used in the present in this experiment. Earthen pots of 24.5 cm top diameter, 14 cm bottom and 30 cm depth were used, which pot was filled with 8 kg sun-dried soil. A polythene lining was I nt. J. Sustain. Crop Prod. 2(3):17-21 ( August 2007) © 2006 Green World Foundation (GWF)