Review: Role of silicon in drought tolerance

There is increasing evidence that silicon (Si) application to soils or leaves can promote plant growth through various means, including enhancing tolerance to abiotic and biotic stresses, but the mechanisms of this growth promotion are not always clear. Here, Bardhan et al. review how Si can promote drought tolerance, focusing on the soil-root interface. Starting with the soil, it has been shown that Si fertilization improves soil water retention, resulting in increased water availability to plants, and Si can also enhance nutrient availability in soil through effects on soil pH. Different plants accumulate different amounts of Si, and their responses to Si augmentation vary, but the collective list of positive benefits of Si is significant. For example, Si can interact with plant cell walls, for example by providing strength with a lower requirement for lignin, which frees up carbon for other functions, and strengthening xylem walls to prevent cavitation. Furthermore, the presence of Si can promote growth of root hairs and lateral roots, providing the infrastructure for water uptake. Some studies have also shown that Si indirectly enhances plant growth through effects on the plant microbiome. Although we still have gaps in our understanding of some of the ways that Si promotes drought tolerance, the evidence to support is use as a soil fertilizers is impressive. (Summary by Mary Williams @PlantTeaching) J Agron Crop Sci 10.1111/jac.12721