Data from: Climate warming and plant biomechanical defences: silicon addition contributes to herbivore suppression in a pasture grass

1. Plants, notably the Poacae, often accumulate large amounts of silicon
(Si) from the soil. Si has multiple functional roles, particularly for
alleviating abiotic and biotic stresses (e.g. defence against herbivores).
Recent evidence suggests that environmental change, including temperature
changes, can diminish Si accumulation which could affect functions such as
herbivore defence. 2. Using a field warming experiment, we grew a pasture
grass (Phalaris aquatica) that was either supplemented or untreated with
Si (+Si and -Si, respectively) under ambient and elevated (+2.8ºC above
ambient) air temperatures. We quantified soil water, plant growth rates,
Si accumulation, leaf biomechanical properties and in situ relative growth
rates of a herbivorous global insect pest (Helicoverpa armigera). 3. Si
supplementation promoted shoot and root biomass by c. 48% and 61%,
respectively under ambient temperatures, but these gains were not apparent
under warmed conditions. 4. Warmer temperatures reduced Si uptake by -Si
plants by c. 17%, potentially due to the lower levels of soil water
content in warmed plots. Si supplementation, however, increased Si
accumulation in leaves by c. 24% in warmed plots restoring Si levels to
those seen under ambient temperatures. 5. Si supplementation enhanced
biomechanical properties in the leaves, but this was only statistically
significant under ambient temperatures; leaves of +Si plants required 42%
more force to fracture and were 30% tougher at the midrib than leaves of
-Si plants. The relative growth rates of H. armigera declined by 56% when
feeding on +Si plants under ambient temperatures and while Si
supplementation caused a trend towards declining herbivore growth rates
under warmer conditions, this was not statistically significant. 6. We
conclude that climate warming may mitigate the beneficial effects of Si on
Phalaris aquatica in the short term, potentially by reducing Si uptake.
While Si uptake can be restored with Si supplementation, Si-enhanced
biomechanical defences against a global pest may not be fully restored
under warmer temperatures.

1. 植物，尤其是禾本科（Poacae）植物，通常会从土壤中富集大量硅（Si）。硅具有多种功能，尤其在缓解非生物胁迫与生物胁迫（abiotic and biotic stresses）——例如抵御植食者（herbivores）——方面发挥关键作用。最新研究证据表明，包括温度变化在内的环境改变会抑制硅的富集，进而可能影响诸如植食者防御等硅介导的功能。
2. 本研究依托野外增温实验（field warming experiment）平台，在环境温度与增温（较环境温度升高2.8℃）条件下，分别对牧场牧草——球茎虉草（Phalaris aquatica）——施加硅肥补充（+Si组）与不施加硅肥（-Si组）处理。研究团队量化测定了土壤含水量、植物生长速率、硅富集量、叶片生物力学特性，以及全球分布的植食性害虫棉铃虫（Helicoverpa armigera）的原位相对生长速率。
3. 在环境温度条件下，施加硅肥可分别使牧草的地上部与地下部生物量提升约48%与61%，但该增益在增温条件下并未显现。
4. 增温可使-Si组植物的硅吸收量（Si uptake）降低约17%，该现象可能与增温样地的土壤含水量更低有关。而在增温条件下，施加硅肥可使叶片的硅富集量提升约24%，将叶片硅含量恢复至环境温度条件下的水平。
5. 施加硅肥可提升叶片的生物力学特性，但该提升仅在环境温度条件下具有统计学显著性：+Si组植物的叶片断裂所需力较-Si组高42%，且其中脉的韧性较-Si组提升30%。在环境温度条件下，取食+Si组植物的棉铃虫相对生长速率下降了56%；尽管在增温条件下施加硅肥会使植食者的生长速率呈下降趋势，但该趋势未达到统计学显著性水平。
6. 本研究得出结论：短期来看，气候变暖可能通过降低植物的硅吸收量，削弱硅对球茎虉草的有益效应。尽管通过施加硅肥可恢复植物的硅吸收量，但在增温条件下，硅强化的针对全球分布害虫的生物力学防御功能或无法完全恢复。