EFFECTS OF SALINITY ON ION ACCUMULATION IN MAIZE

NaCl salinity in the range of 50 to 200 mM increased Na+ accumulation in the root and shoot of 7-, 14- and 21-day-old maize seedlings. The accumulation of Na+ and Cl- increased but K+ accumulation decreased with the increase in NaCl concentration from 50 to 200 mM in the root and shoot of maize in all the three ages. Salinity is a common abiotic stress factor seriously affecting crop production in different regions, particularly in arid and semi-arid regions. Salinity is the single largest soil toxicity problem, and about 52.8 % of the net cultivable area in the coastal and offshore areas of Bangladesh is affected by varying degrees of salinity (Karim et al. 1990). Salinity stress causes an imbalance in the uptake of mineral nutrients and their accumulation within the plants (Grattan and Grieve 1992). Osmotic stress, ion imbalances, particularly with Ca2+ and K+, and direct toxic effects of Na+ and Cl- ions on the metabolic processes are the most important and widely studied physiological impairments caused by salt stress (Munns 2002, Munns et al. 2006). Maintaining a better nutrition with K+ and Ca2+, while limiting N uptake, is a highly important trait contributing to salt-stress tolerance in plants. Consequently higher K+/Na+ or Ca+/Na+ ratios are typical to the tissues of salt tolerant varieties, and are often used as a screening parameter for identification of salt-stress tolerant varieties, and are often used as a screening parameter for identification of salt-stress tolerant varieties (Munns and James 2003, Song et al. 2006). To grow maize and other crops in the saline areas, understand physiological changes of various crops under salinity is important. This knowledge is useful for the plant breeders to develop salt tolerant crops. Therefore, the present investigation was undertaken to study the effect of NaCl-induced salinity on the accumulation of ions in maize with a view to understand the mechanism of adaptation. Seeds of maize (Zea mays L. cv. BARI-7) were collected from Banglades