Nanosilica modulates C:N:P stoichiometry attenuating phosphorus toxicity more than deficiency in Megathyrsus maximus cultivated in an Oxisol and Entisol

Abstract

Silicon (Si) nanoparticles can attenuate nutritional disorders caused by phosphorus in forages through nutritional homeostasis. This paper aims to evaluate the effects of P deficiency and toxicity in Megathyrsus maximus cultivated in two types of soils and to verify whether Si application via fertigation can mitigate these imbalances. The following two experiments were carried out: cultivation of forage plants in pots with Entisol and Oxisol, in a 3 x 2 factorial design, with three nutritional levels of phosphorus (deficient, adequate, and excessive) and two Si concentrations in the irrigation water (0 and 1.5 mmol L-1). Height, number of tillers, rate of leaf senescence, dry matter production, C:N, C:Si, C:P, and N:P ratios; and C, P, and N use efficiencies were evaluated in two growth cycles. P imbalances hampered carbon assimilation, C:N:P homeostasis, and dry matter production. Nanosilica fertigation promoted silicon uptake, improving C:N:P homeostasis and nutritional efficiency in plants under P deficiency and toxicity. Leaf senescence showed a lower value with addition of Si in plants grown in Oxisol in the three nutritional states of P. Silicon attenuated the stress caused by P toxicity in Entisol and Oxisol, improving production in plants without nutritional stress in Oxisol. The supply of Si nanoparticles in the cultivation of grass forage can contribute to a more efficient and sustainable use of phosphorus in pastures.

Nanosilica improves morphogenic and chemical parameters of Megathyrsus maximus grass under phosphorus deficiency and excess stress in different soils

“…This imbalance impairs the essential functions of P in plants, with a consequent depression in photosynthesis and biomass production [5,8] . It was observed for the rst time in our rst study that the excess of P in the soil reduced the homeostasis between C, N and P in grasses, which impairs the e ciency of use of these nutrients [51] . However, there are still few studies describing the effects of excess P on grass, even in nutrient solution [52] , so our study may be the rst to identify the morphogenic responses of forage grass to P excess in different soils.…”

“…Advances in forage regrowth cycles could further aggravate the P de ciency in the soil with nutrient export in the biomass, and Si could increase its bene ts in the plant. Nevertheless, future research must prove it [51] .…”

Nanosilica enhances morphogenic and chemical parameters of Megathyrsus maximus grass under conditions of phosphorus deficiency and excess stress in different soils

“…This imbalance affects essential P-related functions in plants, leading to decreased photosynthesis and biomass yield [ 5 , 8 ]. Our study suggests, for the first time, that an excess of P in the soil disrupts the balance between C, N, and P in grasses, subsequently hindering the efficient utilization of these nutrients [ 58 ]. However, there is still a limited number of studies describing the effects of excess P on grasses, even in nutrient solutions [ 59 ].…”