Simultaneous Biofortification of Rice With Zinc, Iodine, Iron and Selenium Through Foliar Treatment of a Micronutrient Cocktail in Five Countries

Abstract

Widespread malnutrition of zinc (Zn), iodine (I), iron (Fe) and selenium (Se), known as hidden hunger, represents a predominant cause of several health complications in human populations where rice ( Oryza sativa L.) is the major staple food. Therefore, increasing concentrations of these micronutrients in rice grain represents a sustainable solution to hidden hunger. This study aimed at enhancing concentration of Zn, I, Fe and Se in rice grains by agronomic biofortification. We evaluated effects of foliar application of Zn, I, Fe and Se on grain yield and grain concentration of these micronutrients in rice grown at 21 field sites during 2015 to 2017 in Brazil, China, India, Pakistan and Thailand. Experimental treatments were: (i) local control (LC); (ii) foliar Zn; (iii) foliar I; and (iv) foliar micronutrient cocktail (i.e., Zn + I + Fe + Se). Foliar-applied Zn, I, Fe or Se did not affect rice grain yield. However, brown rice Zn increased with foliar Zn and micronutrient cocktail treatments at all except three field sites. On average, brown rice Zn increased from 21.4 mg kg –1 to 28.1 mg kg –1 with the application of Zn alone and to 26.8 mg kg –1 with the micronutrient cocktail solution. Brown rice I showed particular enhancements and increased from 11 μg kg –1 to 204 μg kg –1 with the application of I alone and to 181 μg kg –1 with the cocktail. Grain Se also responded very positively to foliar spray of micronutrients and increased from 95 to 380 μg kg –1 . By contrast, grain Fe was increased by the same cocktail spray at only two sites. There was no relationship between soil extractable concentrations of these micronutrients with their grain concentrations. The results demonstrate that irrespective of the rice cultivars used and the diverse soil conditions existing in five major rice-producing countries, the foliar application of the micronutrient cocktail solution was highly effective in increasing grain Zn, I and Se. Adoption of this agronomic practice in the target countries would contribute significantly to the daily micronutrient intake and alleviation of micronutrient malnutrition in human populations.

Iodine Biofortification of Apples and Pears in an Orchard Using Foliar Sprays of Different Composition

“…Further field experiments are needed to examine the effects of appropriately increased Se fertilization rate in combination with I. In the leaves of the apple trees we examined, the Se content was several times higher than in the fruits, as already observed with I. Translocation of I and Se from leaves to seeds in wheat is mainly through phloem transport ( Cakmak et al, 2017 ; Prom-u-thai et al, 2020 ), while our findings indicate that this route does not seem important for biofortification of pome fruits.…”

“…This confirms results from previous studies on apple trees ( Budke et al, 2020a ). Likewise, in studies on the biofortification of lettuce and rice, no interactions between IO 3 – and SeO 4 2– were found with regard to the uptake of both trace elements ( Smoleń et al, 2014 , 2016b ; Prom-u-thai et al, 2020 ). In contrast, in field experiments with carrots and wheat, a slight reduction of I accumulation in the edible plant parts was observed when Se was simultaneously applied to the soil or Se and other micronutrients to the leaf ( Smoleń et al, 2016a ; Zou et al, 2019 ).…”

Joint Biofortification of Plants with Selenium and Iodine: New Field of Discoveries

“…In plants, the aforementioned threshold referred to Se and I is species- and variety-dependent, which determines significant differences in the enrichment efficiency with these microelements [ 16 , 21 , 25 , 29 , 30 ].…”

“…Attempts to quickly solve the deficiency problem of a whole set of trace elements, such as Se, I, Fe, Zn, in the conditions of different countries worldwide, were achieved in cereals (10 wheat cultivars and 7 rice cultivars) in 2019 and 2020, using foliar application of elements cocktail. These works revealed the efficiency of such biofortifications, but lack of significant effect on wheat yield and just a slight increase of rice yield [ 29 , 30 ]. In those conditions, the multiplicity of microelements used did not allow the evaluation of their interaction, particularly between Se and I.…”

The Potential of High-Anthocyanin Purple Rice as a Functional Ingredient in Human Health

“…At least 175 countries and territories consume rice; the overall consumption is high in the rice-consuming countries, ranging from 100 to 200 kg of paddy rice per person per year according to the FAO. This could be one of the reasons why many international programs aimed at boosting human nutrition, e.g., the harvest plus biofortification with high zinc, iron, iodine, and selenium, are focused on rice crops [ 10 ]. Moreover, it is interesting to observe that among the staple food crops, rice is recognized as potentially containing high amounts of antioxidant compounds such as anthocyanin, especially in pigmented rice varieties with black (purple) and red pericarp color [ 11 ] ( Figure 1 ).…”