Effect of Lanthanum on the growth and physiological activities of Zea mays, Vigna radiata and Vigna mungo

Corn (Zea mays), green gram (Vigna radiata) and black gram (Vigna mungo) seeds were grown in Hoagland half strength solution containing 5, 10, 15 up to 50 μM La in order to assess the effect of La on growth and physiological activities of these plants. We observed increase in germination percentage, root length, shoot length, fresh and dry weight of all the three plants with increase in lanthanum proportion in the growth medium. However, the magnitude of effect varied in different species. La did enhance the growth of V. radiata, V. mungo as well as Z. mays but it was Z. mays which showed best results among the three plants. An increase in Chlorophyll a, b and total content further indicated the stimulating effect of La on physiological activities of the selected plants. Based upon the results of this preliminary investigation we can say that except of strongly acidic conditions, the application of La does not present a risk for plant growth in near future, provided that the recommended doses are not exceeded. As suggested by previous researchers La can also be used as a feed additive for poultry animals which further reduces the problem of post harvest utilization of the plant species used for the Phytoremediation or phytoextraction of La.