Silicon Mitigates Nutritional Stress of Nitrogen, Phosphorus, and Calcium Deficiency in Two Forages Plants

Abstract

Forages are one of the most cultivated crops in the world. However nutritional deficiency is common, specifically in N, P and Ca in many forages growing regions. Silicon (Si) can attenuate the stress caused by nutritional deficiency, but studies on the effects of Si supply on in forages plants are still scarce. This research was carried out to evaluate whether the Si supply can mitigate the effects of N, P and Ca deficiencies of two forages and the physiological and nutritional mechanisms involved. Two experiments were carried out with two forage species (Urochloa brizantha cv. Marandu and Megathyrsus maximum cv. Massai). Was used nutrient solution under balanced nutrition conditions and nutritional stress due to the lack of N, P and Ca combined with the -Si and +Si. The deficiencies of N, P and Ca in both forages cultivation caused damage to physiological and nutritional variables, hence decreasing the plant dry matter. However, in both species forages the addition of Si to the nutrient solution decreased the extravasation of cellular electrolytes and increased the content of phenolic compounds, the green color index, the quantum efficiency of photosystem II, the efficiencies of use of N, P and Ca and the production of shoot dry mass. The beneficial effects of Si were evidenced in stressed and non-stressed plants. The research emphasized the advantage of using Si for the growth of U. brizantha and M. maximum under N, P and Ca deficiency, contributing to their sustainable cultivation.

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

“…The role played by silicon as a facilitator of the balance of mineral nutrients in the plant and a mediator of morphological and biochemical changes [103,104] may explain the increase in plant growth even without nutritional stress. Furthermore, high levels of Si in the shoots, such as those found in this study, favor the expression of the bene ts of Si to plants, with recent studies reporting production gains due to stoichiometric balance and e ciency in the use of macronutrients such as N and P in different species cultivated without stress, such as forage plants cultivated in a hydroponic system [36,44] , sugarcane [105,37] , and sorghum [106] .…”

“…Therefore, P de ciency in relation to P-su cient plants reduced nutritional homeostasis and the use e ciency of C and N, affecting forage plant growth in both cycles and in the two soils studied, with a decrease in dry matter production dries of 50 and 31% in plants grown in Oxisol and Entisol, respectively. These losses have been commonly reported in Poaceae cultivated under low levels of P [79,44] , limiting the productive capacity of pastures in tropical soils [4,3] .…”

“…A new approach discusses the bene ts of Si for nutrient uptake in plants under limiting conditions [42] and for the modi cation of C:N:P stoichiometry in grasses, attenuating the water de cit [38,43] and nutritional de ciency in forage plants under hydroponic cultivation [44] . This change in C stoichiometry must be related to the incorporation of Si into the cell wall, being metabolized at a low energy cost compared to the synthesis of structural carbon compounds such as lignin [45,46] , and these factors may favor plant growth under stress.…”

Impact of Silicon on Plant Nutrition and Significance of Silicon Mobilizing Bacteria in Agronomic Practices

“…Further, it decreases the extravasation of cellular based electrolytes. Ability of a plant to uptake N, P and S nutrient in deficient soils enhanced the yield of Urochloa brizantha and Megathyrus maximum which revealed Si can be used to amendment under nutrient deficient soil [268]. In maize, soil application or foliar spray of Si alleviate the K deficiency and enhanced growth and yield.…”