Alleviation of nickel-induced stress in mungbean through application of gibberellic acid

Nickel (Ni) is the most eco-toxic and harmful metal for soil biological activity, plant metabolism and health of animals and human beings. Elevated level of Ni in plants causes many nutritional and physiological disorders as well as perturbs in normal balance of phytohormones. Exogenous application of phytohormones can regulate plant growth and reduce inhibitory effect of toxic metals on plants. Therefore present study was conducted to assess the effect of Ni contamination on growth and yield of mungbean and role of gibberellic acid (GA3) to counteract negative effects of Ni contamination. Mungbean seeds were sown in potted soil contaminated with different levels of Ni (0, 20, 40, and 60 mg kg-1). Two sets of Ni contamination levels were maintained, one set was kept without application of GA3 while in second set 10-4 M GA3 was applied as foliar spray at 15, 30 and 45 days after germination. Significant reduction in all growth and yield attributes of mungbean was recorded in Ni contaminated pots. However, application of GA3 enhanced the length, fresh and dry weight of shoots and roots as well as grain yield of mungbean in Ni contamination. Moreover, Ni concentration was increased in roots and shoots of mungbean with increasing levels of Ni contamination from 0 to 60 mg kg-1. But, application of GA3 caused significant decrease in Ni concentration in roots and shoots of mungbean in Ni contaminated soil. It is concluded that use of GA3 could be very effective to improve plant growth through reduced Ni uptake by plants in the Ni contaminated soils.