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• A declining grain density of Fe and Zn in cultivars of rice and wheat in past 50 years in India. • Newer-released (1990s and later) cultivars were stubborn to Fe and Zn application. • Application of one element had inhibitory effect on accumulation of the other. • Such inhibitory effect was magnified along succeeding decades since green revolution. Zinc and iron deficiency is a serious global health problem in humans depending on cereal-diet and is largely prevalent in low-income countries like Sub-Saharan Africa, and South and South-east Asia. We report inefficiency of modern-bred cultivars of rice and wheat to sequester those essential nutrients in grains as the reason for such deficiency and prevalence. To substantiate, experiments were conducted with elite, high-yielding cultivars of rice (n = 16) and wheat (n = 18) released in succeeding decades since the beginning of green revolution in India. The inherent Zn and Fe sequestering capacity in grains of the cultivars, and their responses to external application of Zn and Fe fertilizers were evaluated following standard protocols. We found a downward trend in grain density of Zn and Fe in those cereals in past more than 50 years. However, we failed to notice yield-dilution as a causative effect for such unwitting downward trend. With time, the cultivars again became stubborn to Zn and Fe fertilization for enhancing their grain density. Further, we noticed that external supply of one element, to improve its density in grains, had inhibitory effect on accumulation of the other, and the effect was magnified along the succeeding decades. Our innovative research warrants an improvement in ionomes of the cereals to alleviate the said incapacitating effect and ultimately the deficiency of those elements in humans, particularly living in low-income countries. [ABSTRACT FROM AUTHOR]