EFFECT OF CADMIUM TOXICITY ON Zn, Mn, Cd, Fe CONCENTRATION AND TRANSLOCATION, BIOACCUMULATION, UPTAKE OF Cd IN ROOT AND SHOOT OF DIFFERENT RICE VARIETIES

Rice (Oryza sativa L.) is found a paramount contributor (>75%) of Cd contamination in the food chain in many countries of Asia, including Pakistan. In the present study, twenty local rice varieties were selected and the varietal response was investigated against Cd application with four strengths (0, 5, 10, and 15 mu M) under hydroponic conditions by following completely randomized design under the factorial arrangements along with three replicates. Results regarding Cd concentration in roots and shoots revealed that the maximum level of Cd was assessed in V-20 (IRRI-6) and minimum in V-1 (Super Basmati) when Cd was applied at a higher level (15 mu M), while higher Cd uptake in roots and shoots was exhibited by V-20 (IRRI-6) and V-13 (KS-282) respectively and minimum in V-1 (Super Basmati) among both ones at Cd application with strength 15 mu M. Maximum translocation and bioaccumulation of Cd in roots and shoots were observed in V-20 (IRRI-6) and minimum in V1 (Super Basmati). Zinc level in root was higher in V-4 (Shaheen Basmati) and minimum in V-14 (KSK-133), while, in shoots V7 (Basmati-515) exhibited maximum Zn concentration and minimum by V-2 (Kainat Basmati). Maximum Mn level in roots against Cd application were observed in V-4 (Shaheen Basmati) and minimum in V-2 (Kainat Basmati), whereas its level was higher in shoots of V-13 (KS-282) and lower in V-8 (Pak Basmati). Iron contents were higher in roots of V-5 (Basmati-198) and lower in V-20 (IRRI-6), while, in shoots, Fe level was higher in shoots of V-8 (Pak Basmati) and minimum in V-2 (Kainat Basmati) against Cd application. V-1 (Super Basmati) showed a positive response against Cd contaminations. This study enlightens the era for others to assess the impact of heavy metals on various crops. Increasing the Cd concentration higher the binding to sulfhydryl groups in proteins and enzymes that inactive and disturb the metabolic pathway of rice plant and decrease uptake of essential nutrients. Cd competes with the nutrients and damages the plant nutrients balance and create physiological stress.