Climate change has aggravated the occurrence of drought periods, affecting pasturelands in different regions of the world. Silicon attenuates water deficiency in several species, but there is a lack of research to verify whether Si can modify C stoichiometry and its effects in mitigating water deficit in forage plants. To this end, this research was carried out with the aim of evaluating whether Si supply via fertigation causes an increase in its absorption, stoichiometric modification of C and improvement in physiological variables and in the growth of Brachiaria cultivated under two soil water regimes (70% and 40% of water holding capacity in the soil). Two experiments were carried out with the cultivars BRS RB331 Ipyporã and Mavuno grown in pots filled with Quartzipsamments. In the experiments, the same treatments arranged in a 2 × 2 factorial scheme were applied, with Si application via fertigation applied to the soil and control (Si omission) combined with two soil water regimes (70% and 40% of the water retention capacity in the soil, adequate and deficient water contents, respectively). The two forages that received silicon via fertigation specially cultivated under water deficit had a greater accumulation of Si in the shoot, decreased C content and C:Si ratio and increased C use efficiency, and decreased rate of electrolyte leakage with increased relative water content, leaf water potential, chlorophyll b content, quantum efficiency of photosystem II and, consequently, increased growth and dry matter production. The present research shows that the use of Si via fertigation promotes a new strategy to mitigate water deficit in forages, based on the improvement of the physiological aspects of the plant resulting from the modification of carbon stoichiometry, thereby increasing C use efficiency.

中文翻译：

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Si 灌溉施肥通过改变碳化学计量来减轻牧草的水分胁迫，有利于生理方面

气候变化加剧了干旱期的发生，影响了世界不同地区的牧场。硅可以减轻几种物种的缺水，但缺乏研究来验证硅是否可以改变 C 化学计量及其在减轻牧草植物缺水方面的作用。为此，开展本研究的目的是评估通过灌溉施肥提供 Si 是否会导致其吸收增加、C 的化学计量修饰和生理变量的改善以及在两种土壤水分条件下（70%和 40% 的土壤持水能力）。使用在装有 Quartzipsamments 的花盆中生长的栽培品种 BRS RB331 Ipyporã 和 Mavuno 进行了两个实验。在实验中，应用以 2 × 2 因子方案排列的相同处理，通过施肥施硅施用于土壤和对照（Si 省略）结合两种土壤水分状况（土壤中保水能力的 70% 和 40%，水含量分别充足和不足）。水分亏缺条件下施肥施硅的两种牧草，茎秆中Si积累较多，C含量和C:Si比降低，C利用效率提高，电解质渗漏率降低，相对含水量增加，叶片水势，叶绿素 水含量分别充足和不足）。水分亏缺条件下施肥施硅的两种牧草，茎秆中Si积累较多，C含量和C:Si比降低，C利用效率提高，电解质渗漏率降低，相对含水量增加，叶片水势，叶绿素 水含量分别充足和不足）。水分亏缺条件下施肥施硅的两种牧草，茎秆中Si积累较多，C含量和C:Si比降低，C利用效率提高，电解质渗漏率降低，相对含水量增加，叶片水势，叶绿素b含量，光系统 II 的量子效率，从而增加生长和干物质产量。目前的研究表明，基于碳化学计量学改变导致植物生理方面的改善，通过灌溉施肥使用硅促进了减轻草料水分亏缺的新策略，从而提高了碳的利用效率。