**4. Discussion**

The present results agree with those of Lima et al. [19] who observed increases in dry biomass of leaves, stems, and roots in maize seedlings with the application of 1 mmol L-1 of Si via nutrient solution.

Many authors have pointed out the increase of silicon accumulation in different crops as a response to the application of this beneficial element in corn [12, 20] and in rice under hydroponic conditions [11].

The increase of K accumulation in the aerial part of the plant with the application of high concentrations of this nutrient agrees with the results of Andreotti et al. [7] who obtained an increment of the concentration of K with an increase of the doses of K.

Increments in N accumulation as a function of N doses were also obtained in the aerial part of the maize plants (leaves, stems, cob, straw, and grains) by Gava et al. [21]. There are other results that also show that increases in N doses caused higher development and yield of corn plants [21, 22].

The total dry biomass in the aerial part of the plant was increased with the presence of Si, which agrees with the results of Rohanipoor et al. [23], who reported increases in the leaf area of the corn crop under different doses of Si. Also, González et al. [15] observed increases in plant height and green forage of the Morocho Blanco corn variety under hydroponic conditions when they applied an intermediate dose of Si, in relation to nonapplication. They attributed this to a synergism between Si and K.

No results were found in the literature on the influence of the interaction of the presence of Si with a high concentration of potassium on the gain of the dry biomass, however, Miaoo et al. [24] reported that in the soybean plants there was a positive effect of silicon on the increase of root length and its density subjected at low concentration of K (1 mmol L−1). They attributed this to the action of Si on the affectation of the peroxidase enzyme, but this effect was not demonstrated for the case of maize in an experiment in which the plants were subjected to a low concentration of K [10].

The increase in the accumulation of dry matter observed with the application of Si can be associated with its protective effects of the photosynthetic apparatus of the plants, in the improvement of the efficiency of water use and the balance of mineral nutrients as indicated by Mateos-Naranjo et al. [25]. Other researchers have attributed this increment of biomass to the beneficial effects of Si against the oxidative damage of plant membranes and the increase of the cell wall extension capacity [9].

Other investigations have shown that Si increases stomatal conductance by promoting better water use efficiency [26], inducing increased transpiration, which may lead to increased absorption of K, an element that participates actively in the closure and opening of the stomata [25].

The role of Si in the uptake of K was verified in the present research, but this effect does not occur at low and high concentrations of N. The increase of K at 10 mmol L−1 of N without application of Si can be explained by the small amounts of Si which remains in the water as indicated by Raya and Aguirre [6], despite being deionized in the experiment.

Parveen and Ashraf [27] also observed increases in dry biomass of the roots in corn plants with the application of 2 mmol L−1 of Si in relation to the nonapplication of this element combined with N at 10 mmol L−1 under hydroponic conditions.

The results obtained have relation to those of Mauad et al. [11] in rice, who observed a higher concentration of Si in the plant at the lowest dose of N combined with a normal dose of K, independently of the presence or absence of silicon, which show the role of the beneficial element in the presence of plant stress by N.

*Silicon, Potassium and Nitrogen Accumulation and Biomass in Corn under Hydroponic… DOI: http://dx.doi.org/10.5772/intechopen.100628*

Castellanos et al. [13] also stated that the interaction of N and K influenced the accumulated silicon in corn with an optimum at 11.4 mmol L−1 of N. Similar results were obtained by Mauad et al. [11] who observed a decrease in the deposition of silica in leaves of rice plants at high doses of N.

Increments of dry biomass and productivity of corn as increase the concentration of N have also been obtained by other authors as Queiroz et al. [1].

The nitrogen effects on dry biomass gain was confirmed since this element is a constituent of all molecules, proteins, enzymes, coenzymes, nucleic acids, and cytochromes, as well as its important function as a member of the molecule of chlorophyll, as have been pointed out by Pina et al. [28].
