Biofortification of diverse basmati rice cultivars with iodine, selenium, and zinc by individual and cocktail spray of micronutrients

Official URL: https://dx.doi.org/10.3390/agronomy12010049

Given that an effective combined foliar application of iodine (I), selenium (Se), and zinc (Zn) would be farmer friendly, compared to a separate spray of each micronutrient, for the simultaneous biofortification of grain crops, we compared effectiveness of foliar-applied potassium iodate (KIO3, 0.05%), sodium selenate (Na2SeO4, 0.0024%), and zinc sulfate (ZnSO4 ·7H2O, 0.5%), separately and in their combination (as cocktail) for the micronutrient biofortification of four Basmati cultivars of rice (Oryza sativa L.). Foliar-applied, each micronutrient or their cocktail did not affect rice grain yield, but grain yield varied significantly among rice cultivars. Irrespective of foliar treatments, the brown rice of cv. Super Basmati and cv. Kisan Basmati had substantially higher concentration of micronutrients than cv. Basmati-515 and cv. Chenab Basmati. With foliar-applied KIO3, alone or in cocktail, the I concentration in brown rice increased from 12 to 186 µg kg−1. The average I concentration in brown rice with foliar-applied KIO3 or cocktail was 126 µg kg−1 in cv. Basmati-515, 160 µg kg−1 in cv. Chenab Basmati, 153 µg kg−1 in cv. Kisan Basmati, and 306 µg kg−1 in cv. Super Basmati. Selenium concentration in brown rice increased from 54 to 760 µg kg−1, with foliar-applied Na2SeO4 individually and in cocktail, respectively. The inherent Zn concentration in rice cultivars ranged between 14 and 19 mg kg−1 and increased by 5–6 mg Zn per kg grains by foliar application of ZnSO4 ·7H2O and cocktail. The results also showed the existence of genotypic variation in response to foliar spray of micronutrients and demonstrated that a foliar-applied cocktail of I, Se, and Zn could be an effective strategy for the simultaneous biofortification of rice grains with these micronutrients to address the hidden hunger problem in human populations.