Sexual reproduction and cadmium partitioning in two mungbean genotypes raised in soils contaminated with cadmium

Plants of two mungbean genotypes MH 85-111 and MH 98-6 were exposed to different levels of cadmium 28 days after sowing. Plants exposed to 3.0 and 4.0 mM Cd⁺² did not survive and died before entering into reproductive phase. Cadmium induced reduction in the number of flowers and in vitro pollen germination but did not affect pollen viability. However, it stimulated tube growth. Cadmium although did not affect pistil length, it decreased number of ovules/pistil. Ovules were morphologically normal and receptive. In vivo stylar studies revealed all the ovules were not penetrated by pollen tube and number of unpenetrated proximal ovules was increased by Cd⁺² and cv. MH 85-111 was affected more adversely than MH 98-6. Cadmium inhibited number of pods, seeds, seed weight/plant and 100 seed weight, inhibition being more in MH 85-111 than MH 98-6. Cadmium treatment did not affect starch content but increased protein content in physiologically mature seeds. Accumulation of Cd⁺² was maximum in the roots and least in the seeds. Cadmium accumulation, in general was higher in MH 85-111 than MH 98-6 and stem of MH 85-111 accumulated four times Cd⁺² than MH 98-6. Seed cadmium however, was comparable in both the genotypes.