Exploring sustainable strategies for improving crop water and nitrogen use efficiency is essential. Silicon (Si) has been reported as a beneficial metalloid for plants since it alleviates several abiotic stresses (including drought) by triggering the plants' antioxidant system. However, its role in mitigating the negative impact of nitrogen (N) deficit alone or when combined with water (W) deficit is not well studied. This study applied 0 or 2 mM of Na₂SiO₃ to 3-week-old tomato cv. Micro-Tom seedlings that were grown under the following conditions: control (CTR; 100%N + 100% Field Capacity), N deficit (N; 50% N + 100% Field Capacity), water deficit (W; 100% N + 50% Field Capacity) or combined stress (N + W; 50% N + 50% Field Capacity). The Si effect on tomato plant growth depended on the type of stress. Si could only alleviate stress caused by N + W deficit resulting in a higher root dry weight (by 28%), total dry weight (by 23%) and root length (by 37%). Alongside this, there was an increase in the antioxidant (AOX) system activity with the root activity of ascorbate peroxidase and catalase enzymes being enhanced by 48% and by 263%, respectively. Si application also enhanced AOX enzyme activity when tomato plants were subjected to individual deficits but to a lesser extent. In conclusion, Si-treated tomato plants could efficiently modulate their AOX networks in a situation of combined N and water limitation, thus mitigating some of the adverse effects of this combined stress.

中文翻译：

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硅对单独和复合氮水亏缺条件下番茄幼苗抗氧化系统的影响

探索提高作物水和氮利用效率的可持续策略至关重要。据报道，硅（Si）是一种对植物有益的非金属，因为它可以通过触发植物的抗氧化系统来减轻多种非生物胁迫（包括干旱）。然而，其在单独缓解氮 (N) 缺乏或与水 (W) 缺乏结合时的负面影响方面的作用尚未得到充分研究。本研究将 0 或 2 mM Na2SiO ₃施用到 3 周龄的番茄品种中。在以下条件下生长的 Micro-Tom 幼苗：对照（CTR；100%N + 100% 田间持水量）、氮缺乏（N；50% N + 100% 田间持水量）、水分缺乏（W；100% N + 50% 田间承载力）或组合应力（N + W；50% N + 50% 田间承载力）。硅对番茄植株生长的影响取决于胁迫类型。Si只能缓解N+W亏缺引起的胁迫，导致根干重（增加28％）、总干重（增加23％）和根长（增加37％）。除此之外，抗氧化 (AOX) 系统活性也有所增加，抗坏血酸过氧化物酶和过氧化氢酶的根部活性分别增强了 48% 和 263%。当番茄植株遭受个体缺陷时，硅的施用也增强了 AOX 酶的活性，但程度较小。总之，硅处理的番茄植株可以在氮和水联合限制的情况下有效调节其 AOX 网络，从而减轻这种联合胁迫的一些不利影响。