Cover crops are important components of sustainable agricultural systems under no-till conditions. However, in the Brazilian Cerrado region, plant growth and straw production on the soil surface have been hampered by insufficient soil water availability during off-season. A pot experiment was conducted to investigate the effect of silicon fertilization on the morphological and physiological characteristics of cover crops under drought stress conditions. We hypothesized that silicon could mitigate the adverse effects of drought stress because of its role in improving the photosynthetic process and antioxidant defence mechanisms of plants. Thus, two silicon fertilizer levels (0 and 180 mg/kg of Silicon), three grass cover crops (Urochloa brizantha cv. BRS Piatã, U. brizantha cv. Marandu and Pennisetum glaucum cv. ADR 300) and three drought stress levels (100% pot capacity (PC): well-watered conditions, 50% PC: moderate water stress and 25% PC: severe water stress) were laid out as a randomized block design in a factorial arrangement and replicated four times. Morphophysiological characteristics were recorded after 22 days of exposure to drought stress. Drought stress decreased the growth rate, leaf area (LA), net CO₂ assimilation rate and stomatal conductance of the three cover crops. However, with the application of silicon fertilizer, a portion of the negative effects caused by water restriction could be mitigated, even though there were differences in the responses to silicon fertilization and water stress levels among the cover crop species. Silicon application potentiated the tillering and plant growth rate and increased the photosynthetic rate and water use efficiency of U. brizantha (cv. Marandu and cv. BRS Piatã) plants grown under moderate drought stress conditions.

中文翻译：

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硅减轻覆盖作物中度干旱胁迫的影响

覆盖作物是免耕条件下可持续农业系统的重要组成部分。然而，在巴西塞拉多地区，由于淡季期间土壤水分不足，土壤表面的植物生长和秸秆生产受到了阻碍。通过盆栽试验研究了硅肥对干旱胁迫条件下覆盖作物形态和生理特性的影响。我们假设硅可以减轻干旱胁迫的不利影响，因为它可以改善植物的光合作用过程和抗氧化防御机制。因此，两种硅肥水平（0 和 180 mg/kg 硅），三种草覆盖作物（Urochloa brizantha cv. BRS Piatã, U. brizantha简历。Marandu 和Pennisetum glaucum cv。ADR 300）和三个干旱胁迫水平（100% 盆栽容量 (PC)：浇水充足的条件，50% PC：中度缺水和 25% PC：严重缺水）被布置为因子排列中的随机区组设计并重复四次。在暴露于干旱胁迫22天后记录形态生理学特征。干旱胁迫降低了生长速率、叶面积 (LA)、净 CO ₂三种覆盖作物的同化率和气孔导度。然而，随着硅肥的施用，限水造成的部分负面影响可以得到缓解，尽管覆盖作物对硅肥的反应和水分胁迫水平存在差异。硅的应用增强了在中等干旱胁迫条件下生长的U. brizantha (cv. Marandu 和 cv. BRS Piatã) 植物的分蘖和植物生长速率，并提高了光合速率和水分利用效率。