Zn II deficiency in paddy soil. Our experimental results indicate that PDMA is a strong chelator, with a stability sequence of Mg II < Mn II < Fe II < Co II < Zn II < Ni II < Fe III ≤ Cu II , able to form stable complexes with Zn II between pH 6 and 9. This behaviour is comparable to DMA and other ligands naturally exuded by rice. PDMA does not compete with DMA in