EFFECT OF POTASSIUM APPLICATION ON THE GROWTH AND Fe/Zn USE EFFICIENCY OF SALT-TOLERANT AND SENSITIVE MAIZE GENOTYPES IN RESPONSE TO SALINITY

Status of mineral nutrient in plant body play an important role in improving its response to any environmental hazard like water stress, salt stress and heavy metal stress etc. Along with other mineral nutrients, potassium has an important task regarding plants endurance under salt stress condition. It is very important for maintaining turgor and membrane potential, balancing osmotic potential, controlling stomatal movement and activating enzymes. Addition of potassium in growing medium improved salinity tolerance in rice, wheat and corn. Results of previous research depicted that high concentration of potassium in plant body greatly reduced the production of reactive oxygen species. With the objective to combat salinity stress in maize a pot study to investigate the effect of K application on the growth and Fe/Zn use efficiency of salt-tolerant and sensitive maize genotypes. In this experiment two maize (Zea mays L.) genotypes, one salinity sensitive and one salinity tolerant (on the basis of study I) were used. Seeds of each cultivar were sterilized in HgCl2 solution (0.1%) for 10 min and after rinsing these seeds with distilled water they were sown in plastic pots containing well washed gravels. The seedlings were allowed to grow for 15 days. Uniform sized seedlings were transferred to a hydroponic system comprising of plastic tubs filled with Hoagland's nutrient solution (half strength). The treatments in this experiment include different levels of NaCl and potassium. The concentrations of potassium were 1 and 1.5 mM of the Hoagland nutrient solution with 0 or 100 mM NaCl. The salinity treatment was developed by adding sodium chloride (NaCl) to the nutrient solution after four days of transplantation to the hydroponic system. There were four replications of each treatment. The plants were allowed to grow in the treatment solutions for 28 days and at harvest the data regarding root/ shoot lengths, root/shoot fresh and dry weights were recorded. The oven dried shoot samples were analyzed for ion contents including Zn, Fe, Na+ and K+ It was concluded that in saline soil maize yield may improve by the application of K and increase of the concentration in maize grains can improve human nourishment.