Nutritional deficiency is common in several regions of quinoa cultivation. Silicon (Si) can attenuate the stress caused by nutritional deficiency, but studies on the effects of Si supply on quinoa plants are still scarce. Given this scenario, our objective was to evaluate the symptoms in terms of tissue, physiological and nutritional effects of quinoa plants submitted to nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) deficiencies under Si presence. The experiment consisted of a factorial scheme 6 × 2, using a complete solution (CS), -N, -P, -K, -Ca, -Mg combined with absence and presence of Si (1.5 mmol L−1). Symptomatic, physiological, nutritional and evaluation vegetative were performed in quinoa crop. The deficiencies of N, P, K, Ca and Mg in quinoa cultivation caused visual symptoms characteristic of the deficiency caused by respective nutrients, hence decreasing the plant dry mass. However, Si supply attenuated the deficiency effects by preserving the photosynthetic apparatus, increasing the chlorophyll production, increasing the membrane integrity, and decreasing the electrolyte leakage. Thus, the Si supply attenuated the visual effects provided by deficiency of all nutrients, but stood out for N and Ca, because it reflected in a higher dry mass production. This occurred because, the Si promoted higher synthesis and protection of chlorophylls, and lower electrolyte leakage under Ca restriction, as well as decreased electrolyte leakage under N restriction.

Calcium (Ca) deficiency in cabbage plants induces oxidative damage, hampering growth and decreasing quality, however, it is hypothesized that silicon (Si) added to the nutrient solution may alleviate crop losses. Therefore, this study aims at evaluating whether silicon supplied in the nutrient solution reduces, in fact, the calcium deficiency effects on cabbage plants. In a greenhouse, cabbage plants were grown using nutrient solutions with Ca sufficiency and Ca deficiency (5 mM) without and with added silicon (2.5 mM), arranged as a 2 × 2 factorial in randomized blocks, with five replications. At 91 days after transplanting, the plants were harvested for biological evaluations. In the treatment without added Si, Ca deficiency promoted oxidative stress, low antioxidant content, decreased dry matter, and lower quality leaf. On the other hand, added Si attenuated Ca deficiency in cabbage by decreasing cell extravasation while increasing both ascorbic acid content and fresh and dry matter, providing firmer leaves due to diminished leaf water loss after harvesting. We highlighted the agronomic importance of Si added to the nutrient solution, especially in crops at risk of Ca deficiency.

Recognizably, silicon has a beneficial effect on plant growth and productivity. In this respect, it is also known that the C, N and, P stoichiometric ratios and nutrient conversion efficiency allow identifying the interactions between elements while helping to understand the role Si plays in plant growth. This study aims to investigate whether increasing Si concentrations (0, 1, 2, and 3 mmol L−1) supplied in the nutrient solution is uptaken by quinoa, modifies the C:N:P stoichiometry while increasing nutritional efficiency and crop productivity as well. Our results revealed that the Si supply by promoting a decline in the C levels, associated with greater uptake of N and P, especially decreased the C:N and C:P ratios, favoring the C metabolism efficiency, and modulated the N and P use efficiency for biomass accumulation. This improved nutritional performance and greater use efficiency of C directly favored quinoa productivity. The future perspective is to encourage new field studies with this species to adjust silicon fertilization management to different soils aiming at enhancing quinoa productivity on a sustainable basis.

No abstract

No abstract