Physiological quality and dry mass production of Sorghum bicolor following silicon (Si) foliar application

Abstract

The forthcoming of silicon (Si) highly soluble sources provided a suitable alternative to Si use in agroecosystems. There are many benefits associated to Si application in crops, such as improvement in feed quality. In this sense, the aim of this work was to evaluate the effect of Si foliar application on physiological quality, biomass production, and silicon accumulation in Sorghum bicolor. The experiment was conducted under greenhouse condition using an entirely randomized design, with five Si rates (0 as control), 0.84, 1.68, 2.52, and 3.36g L -1 of Si) applied as potassium and sodium silicate, with four repetitions. In each treatment, applied solutions were balanced in potassium in order to isolate the Si effect. The following measurements were taken: growth, biomass production, Si accumulation, and physiological quality. Supplying Si via leaves did not affect the sorghum growth rate and the relative chlorophyll index; however, leaf area increased 23% with the use of 2.36 g L -1 of Si. Physiological variables are influenced by increasing Si rates, with rates close to 1.68 g L -1 of Si causing the best photosynthetic rates and stomatal conductance. The use of potassium silicate as a source of silicon is an alternative for productivity increases up to 30%, but an economic study on the viability of its commercial application in the production chain of Sorghum bicolor is necessary.

Different Sources of Silicon by Foliar Spraying on the Growth and Gas Exchange in Sorghum

“…In sorghum plants evaluated at 60 days after sowing, leaf application of 1.64 g L −1 of potassium silicate increased photosynthetic activity at 4.01 μmol m −2 s −1 (Flores et al 2018). Maghsoudi et al (2016) found an increase in photosynthetic activity in wheat plants in the grain-filling phase, after application of 6 mM of sodium silicate (0.7323 g L −1 ) in comparison to the treatment without silicon.…”

“…K is a very important nutrient for plants because it modulates gas exchange; in addition, it plays a role in the osmotic control of guard cells and as cofactor of activation of several enzymes involved in carbon metabolism in plants, thereby contributing to plant growth (Epstein and Bloom 2006). Considering that the foliar application of Si promoted dry mass accumulation according to a quadratic polynomial fitting, foliar application of 3.36 g L −1 of potassium silicate promoted maximum accumulation of less than 80 mg plant −1 of Si in sorghum evaluated 60 days after sowing (Flores et al 2018). Maize plants evaluated 135 days after sowing had a maximum content of 7.70 g kg −1 of Si when applied via leaf 217.92 g ha −1 of potassium silicate according to a quadratic polynomial fit.…”

“…In sorghum, previous research reports have indicated that the supply of Si through leaves favors plant physiology and plant growth (Flores et al 2018). Biological gains of Si in plants appear to be associated with the indirect effect of Si on photosynthesis and plant metabolism Abdalla 2011;Sandhya et al 2018;Camargo et al 2019) and on the reduction of transpiration, thus increasing water use efficiency (Camargo et al 2017).…”

“…An alternative to silicon fertilization in sorghum is foliar application, which can be performed with soluble Si sources (Flores et al 2018). However, the response of plants to foliar fertilization is concentration-source dependent, which suggests the need to evaluate sources and concentrations that maximize silicon absorption and physiological improvements in plants.…”

Assessing Forms of Application of Azospirillum brasilense Associated with Silicon Use on Wheat

“…In addition, the Si-increased benefits and yields were associated with proline and total sugar accumulation under biotic and abiotic stress conditions [26,65,72]. Silicon use was reported to increase rice [73], maize [74], sugar cane [75], wheat [37,76], sorghum [77], sunflower [78], peanut, soybean, and common bean [79] yields. As this field trial was carried out under irrigation, the stress caused by drought was not evident; moreover, sandy soils are more responsive than clay soils to silicate application [80].…”