Zinc fertilization as an alternative to increase the concentration of micronutrients in edible parts of vegetables

Abstract

Because nutrients consumed by human beings are derived from the soil-plant system, biofortification of the edible parts of horticultural crops can be a very useful technique for countering human malnutrition. The objective of this study is to evaluate the transfer of Zn from the soil to the edible parts of carrots, kale and okra in latosol treated with increasing doses of Zn. The experiment was conducted in a randomized block design with a 4 x 3 x 4 factorial scheme, consisting of four Zn doses (0, 50, 150, and 300 mg kg -1 of soil), three plant species (carrot, kale and okra) and four parts of the plants (root, stem, leaf and edible parts), with four repetitions. It was found that with an increase in the content of Zn in the soil, the plant species, in general, presented a higher concentration of this element, showing that fertilization practices can increase the availability of Zn to plants. The kale plants exhibited a potential to concentrate Zn in their edible parts, as opposed tocarrot and okra plants. For this reason, these are suitable for use in Zn biofortification programs Zn.Key words: biofortification, carrot, human malnutrition, kale, okra Adubação com Zinco como alternativa para aumentar a concentração de micronutrientes em partes comestíveis de hortaliças RESUMOConsiderando que os nutrientes consumidos pelos seres humanos são provenientes do sistema solo-planta, a biofortificação das partes comestíveis de hortaliças pode ser uma técnica muito útil para combater a desnutrição humana. O objetivo deste estudo é avaliar a transferência de Zn do solo para as partes comestíveis de cenoura, couve e quiabo em latossolo tratado com doses crescentes de Zn. O experimento foi conduzido em um delineamento em blocos casualizados com esquema fatorial 3 x 4 x 4, constituído de quatro doses de Zn (0, 50, 150 e 300 mg kg -1 de solo), três espécies vegetais (cenoura, couve e quiabo) e quatro partes de plantas (raiz, caule, folhas e partes comestíveis), com quatro repetições. Verificou-se que com o aumento no teor de Zn no solo, as espécies de plantas, em geral, apresentam maior concentração desse elemento, demonstrando que a prática de fertilização pode aumentar a disponibilidade de Zn para as plantas. Entretanto, as plantas de couve exibiram maior potencial para concentrar Zn nas suas partes comestíveis, em comparação com as plantas de cenoura e quiabo e, por esta razão, são adequados para utilização em programas de biofortificação com Zn.

Foliar application of zinc in the agronomic biofortification of arugula

“…Regarding the Mn contents, no effect of the spraying with zinc was observed. Despite that the observed results diverges from several studies that found antagonism between the two nutrients (Omtiaz et al, 2003;Hasani et al, 2012), the effect of zinc on Mn is not well understood and may vary between species (Lima et al, 2015).…”

“…Several authors have reported a low relationship between Cu contents and applied Zn doses (Fageria, 2002;Mao et al, 2014). Lima et al (2015), working with carrots, okra and cabbage, and increasing doses of Zn applied to the soil, did not observe effect of Zn on leaf Cu contents. Regarding the Mn contents, no effect of the spraying with zinc was observed.…”

“…However, arugula plants not fertilized with Zn did not differ from the fertilized ones in relation to HEO, NL, LA and FMS, which can be attributed to soil zinc content (3.1 mg dm -3 ), considered to be very high by Raij et al (1997), being sufficient to satisfy the nutritional requirement of the micronutrient in arugula. On plants of the same family, several authors verified a positive response to the application of Zn only when this micronutrient was in a low or medium concentration in the culture medium (Singh & Bhatt 2013;Lima et al, 2015).…”

Mineral enrichment in carrot with different sources and doses of zinc

“…Since carrot is a food source of Fe, it becomes important to check any reduction of its content. In the study by Lima et al (2015), Zn levels found in carrot roots increased linearly, whereas a quadratic response was observed in relation to the Fe content in these plants; thus, it was also confirmed that, with application of increasing doses of Zn in the soil, there was a reduction of Fe content in the edible parts of carrot. Smical et al (2008) found that lettuce grown in soil with the addition of Zn (50 to 300 mg kg -1 ) had higher relative contents of Fe in the roots, supporting the natural variation of the plant in relation to preferential assignment of micronutrients to the roots, differing from that found in this study with carrots.…”

“…The application of fertilizers with Zn has shown promising results, Pascoalino (2014) described an average increase of Zn concentration in wheat grains of 1.06 times compared with the control. Therefore, carrot has more potential for Zn biofortification compared with wheat, as this mineral remains more concentrated in the root and has greater difficulty in translocation to aerial parts (Lima et al, 2015).…”