Cadmium Stress Tolerance Through Potassium Nutrition in Soybean

Abstract

Cadmium is known to hamper plant growth through disruption in structure, nutrition, water relations and metabolism in addition to oxidative stress induction. While, potassium has crucial role in the energy status of plants, translocation/storage of assimilates and tissue water relations. Further, it activates over 60 enzyme systems, aids in photosynthesis, regulates stomatal opening and nutrients translocation and enhances synthesis of starch and proteins. These physiological and biochemical aspects of potassium could also be having a remedial role in counteracting the detrimental effects of cadmium. However, such relationship has rarely been studied in detail. Therefore, the study in view was envisaged for exploiting potassium to counter-balance the cadmium toxicity in soybean. Emphasis was laid on growth, physiology and biochemistry of two soybean genotypes differing in cadmium response. Following treatments were employed under factorial design in hydroponics: Check (no cadmium or potassium applied); cadmium only; potassium only; cadmium + potassium. Cadmium reduced growth, chlorophyll content and fluorescence, photosynthesis and stomatal conductance markedly in both genotypes. Enhanced malondialdehyde (MDA) content, super oxide dismutase (SOD) and peroxidase (POD) activities were also detected in plants exposed to cadmium than those with potassium alone or combined with cadmium. The activities of SOD and POD were found higher in cv. Liao-1 than in cv. Zhechun3. Apparently, potassium and cadmium behaved antagonistically; suggesting that potassium could be a candidate for cadmium detoxification in crops cultivated under polluted environments.