The uptake of macronutrients by an active silicon accumulator plant growing in two different substrata

Abstract

Pennisetum clandestinum (Graminae/Poaceae) an active Si-accumulator, was cultivated in two different substrata, both with reduced Si solubility. Plants growing in organic-rich soils contained much less Ca, K, Na and Si, than species growing in sandy soils. Although the highest macronutrient concentrations were associated to the highest Si levels in the organs of P. clandestinum, the R correlation values indicate that Si does not influence the internal balance and the uptake of these elements. In ca 65% of the cases roots have the highest average values regardless of the type of culture, while the contents of Mg in the shoots and roots of P. clandestinum were generally not significantly different (P>0.05). A significant decline of the macronutrient levels associated to the shoots and roots of P. clandestinum was observed from the 4 th to the 6 th month assay, especially for Ca in both organs, while for Mg and Na the decline is focused mainly in the shoots; K and Si decline is generally below 10%. When average values of Si in shoots and roots of plants collected from organicrich and sandy soils were plotted against the average concentrations of Ca, K, Mg and Na in the same organs, weak but positive R correlation values were obtained -the highest R values were observed for Na and K and the lowest for Ca and Mg, regardless of the culture. Exception for the high R value observed for K, although the influence of Si on the K status in the whole plant is time-depending -R values, diminished from the 4 th to the 6 th month, as it happens in the majority of the cases. In conclusion, P. clandestinum can grow well and healthily in substrata with acid pH values and high carbonate content and low solubility of Si suggesting that the definition of the essentiality of Si, even in a Si-accumulator plant is still a matter of great controversy.

Silicon Influences Soil Availability and Accumulation of Mineral Nutrients in Various Plant Species

“…The Mg net accumulation increased with Si addition ( Figure 4 ) and this increase was found as an enhanced Mg concentration in the shoot while no change was found in the roots ( Figure 2 ). According to the literature, Mg content in plants increases by Si; however, at salt stress, Mg content decreases by Si [ 23 , 27 , 28 , 30 ]. Only in sandy soil, Mg availability decreased significantly at the highest Si addition; otherwise the Mg availability was not significantly affected by Si ( Figure 1 ).…”

“…Silicon affects the uptake, distribution and functionality of several mineral nutrients in plants. According to the literature, among the macronutrient elements, nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg) and calcium (Ca) are influenced in different, not unified, ways [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. Among micronutrients, boron (B) and manganese (Mn) seem to be most strongly influenced by Si [ 23 , 36 , 37 , 38 , 39 , 40 ].…”

Silicon nanoparticles (SiNPs) restore photosynthesis and essential oil content by upgrading enzymatic antioxidant metabolism in lemongrass (Cymbopogon flexuosus) under salt stress

“…SiNPs upgraded lemongrass physiology and biochemical status in our case as well. It could be realised by the fact that silicon can escalate the absorption and incarceration of mineral nutrients including nitrogen, phosphorous, potassium, calcium, magnesium, and silicon, and the content of free amino acids, total soluble carbohydrates, and proteins in various plant species (Li et al, 2012;Schaller et al, 2012;Brackhage et al, 2013;Reboredo et al, 2013;Xu et al, 2015;Neu et al, 2017;Xu et al, 2020;Karimian et al, 2021). Further, SiNPs can induce secondary and lateral root growth during salt severity which must have reinforced plant water and nutrient uptake in Mangifera indica (El-Dengawy et al, 2021).…”