In a water shortage crisis, the landscape management of perennial ryegrass, a common lawn grass, is a major challenge. An organic material that can help to overcome this challenge is rice husk biochar (RHB). A pot experiment was carried out to evaluate whether RHB (0%, 5%, and 10% w/w) can mitigate the adverse impacts of drought stress [100%, 50% and 25% of water holding capacity (WHC)] on the growth, physiological and biochemical attributes of perennial ryegrass. When soil was amended with RHB under drought stress, this improved soil physical and chemical properties as well as leaf nutrient content, and increased shoot and root dry weights by 36.27% and 31.36%, respectively compared to the no-biochar treatment. The highest increase in leaf nutrients was 64.77% for Mg2+ and 25.45% for Fe2+. In addition, higher leaf relative water content and nutrient status in plants led to a higher production of chlorophyll (166.97%), and a decrease in the content of proline (−28.79%), hydrogen peroxide (−42.88%) and malondialdehyde (−14.13%). The use of RHB significantly improved visual quality by 30.53% and 50.13% at 50% and 25% WHC, respectively compared to the no-RHB treatment. The amendment of soil with RHB changed soil physico-chemical characteristics and increased nutrient uptake. As a result, shoot and root growth improved, chlorophyll content and photosynthetic efficiency were enhanced, and the drought tolerance of perennial ryegrass ultimately increased. Consequently, the application of RHB, especially at a higher concentration (10%), may be a potential strategy to mitigate drought stress.
