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Water deficit limits the establishment of sugarcane that uses Pre-sprouted seedlings (PSS). Silicon (Si) can mitigate the effects of water deficiency, but it is not known if the Si applied through fertigation is efficient to mitigate damage caused by water deficit at 60 days after transplantation of PSS to the field, nor what physiological and biochemical mechanisms are involved. For this purpose, the objective of this study was to evaluate whether Si applied through fertigation in the PSS production phase of Saccharum officinarum L. (sugarcane) and S. spontaneum L. (energy cane) is efficient in mitigating the effects caused by severe water deficit at 60 days after transplantation. Another objective was to determine the physiological and biochemical mechanisms involved. Two experiments were developed using PSS from sugarcane and energy cane. The treatments consisted of a 2 × 2 factorial scheme, with absence (−Si) and presence of Si (+Si) applied through fertigation (2.5 mmol L−1); combined with water regime: 70% (without deficit) and 30% (severe water deficit) of soil water holding capacity, arranged in randomized blocks with six repetitions. Severe water deficit at 60 days after transplanting decreased the water content and the water potential of the plants, inducing oxidative stress and impairing photosynthetic efficiency, with a consequent decrease in plant growth. Fertigation was shown to be efficient to supply Si in the PSS of sugarcane and energy cane. The residual effect of Si attenuated the damage caused by water deficit at 60 days after transplanting in both species; the mechanisms involved were related to the antioxidant defense system with increased activity of enzymes catalase, superoxide dismutase, ascorbate peroxidase, and proline content. In addition, water status remained stable and, consequently, there was increased plant growth. This study showed that the strategy based on Si supply enables the use of PSS in sugarcane and energy cane, increasing the viability and sustainability of this production system. [ABSTRACT FROM AUTHOR]

Production of sugarcane and more recently of energy cane strengthen renewable bioenergy production capacity. However, droughts resulting from climate change have limited the production of these crops. One of the strategies to attenuate water deficit damage in these crops is the use of silicate, which contributes to plant physiology. This strategy is likely to increase water use efficiency, thus promoting crop sustainability. Notwithstanding, studies on this issue are still incipient. This study assesses whether Si applied via fertigation and foliar spraying in the seedling production phase and as a complement after seedling transplanting to the soil is efficient in attenuating water deficit in sugarcane and energy cane. The study further elucidates physiological and biochemical mechanisms involved in this process. For this, the authors conducted two experiments: one with sugarcane and the other with energy cane. Treatments were arranged in randomized blocks with 5 replications, in a 2 × 2 factorial scheme. Factors consisted of the absence (-Si) and presence of Si (+ Si) applied via fertigation and foliar spraying; and two water regimes: 70% (without water deficit) and 30% (severe water deficit) of the soil water retention capacity. Silicon was supplied during the formation phase of presprouted seedlings and during the transplanting of seedlings to pots filled with samples of Entisol (Quartzipsamment). In these pots, water regimes were induced from 7 to 160 days after transplanting. Severe water deficit reduced the water content and water potential of plants. This situation induced oxidative stress and impaired gas exchange and photosynthetic water use efficiency, reducing plant growth. Silicon supply via fertigation in association with foliar spraying in the seedling formation phase with complementation after transplanting was efficient in increasing Si accumulation in the plants. Silicon was effective in attenuating severe water deficit damage up to initial culm formation through mechanisms that maintain water and physiological balance by favoring the antioxidant defense system in sugarcane and energy cane plants. [ABSTRACT FROM AUTHOR]

Forages are one of the most cultivated crops in the world. However, nutritional deficiency is common, specifically in N, P, and Ca in many forage-growing regions. Silicon (Si) can attenuate the stress caused by nutritional deficiency, but studies on Si supply's effects on forage 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). We 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, decreasing the plant dry matter. However, in both forage species, the Si addition to the nutrient solution decreased the extravasation of cellular electrolytes and increased the content of phenolic compounds, the green colour index, the quantum efficiency of photosystem II, the efficiencies of use of N, P and Ca and the production of shoot dry matter. The beneficial effects of Si were evidenced in stressed and non-stressed plants. The research emphasised the advantage of using Si to grow U. brizantha and M. maximum under N, P, and Ca deficiency, contributing to their sustainable cultivation. [ABSTRACT FROM AUTHOR]