Chia Biofortification With Lithium Sources Applied by Foliar Fertilization

Lithium (Li) is an element considered essential for humans, however, low concentrations in soil, water and food have caused low consumption by the world population. Consequently, fertilization via lithium leaf to increase its concentration in food employing biofortification is an alternative, given the growing health problems in the population caused by low intakes of this trace element.  Thus, the objective was to evaluate doses and sources of lithium, applied by foliar fertilization in the development and productivity of chia, in the south of the state of Tocantins. The experiment was carried out at the Federal University of Tocantins, Campus de Gurupi, in the agricultural year 2016/17 in pots with 8dm3 containing a dystrophic red-yellow Latosol, with a clay texture, in a randomized block design, in a factorial scheme 5x2, with four replicates. The first factor was constituted by five doses (0, 10, 20, 30 and 40 g ha-1) and the second factor by two sources of Li (lithium hydroxide - LiOH and lithium sulfate - Li2SO4). Two applications were carried out by foliar fertilization, the first at 75 and the second at 95 days after transplanting. At 120 days, the characteristics of plant height, the height of the upper stem, stem diameter, bunch length, number of bunches and after harvest (145 days), the weight of a thousand grains, grain yield and Li content were evaluated in the grains. The supply via Li leaf through LiOH and Li2SO4 sources promoted the biofortification of chia grains. The highest concentrations of Li in the grains were obtained with the application of 29.2 and 31.8 g ha-1 of LiOH and Li2SO4, respectively. The best responses in cluster length, thousand-grain mass, and pH were obtained using LiOH. Regardless of the source, doses of lithium above 35 g ha-1 promote a reduction in the morphological and agronomic characteristics evaluated in the culture of chia.