Exogenous silica nanoparticles improve drought tolerance in ginger by modulating the water relationship

Abstract

Drought stress is a worldwide factor limiting the agricultural production. Silica nanoparticles (SiNPs) could improve plant tolerance to drought stress, but their role in ginger salt response and the mechanisms behind it are still unknown. The effect of SiNP100 on drought-stressed ginger was investigated, and four treatments including CK, SiNP100, drought stress (DS), and DS + SiNP100 were performed at 49 days after sowing. The result showed that drought stress exerts a detrimental impact on ginger growth, photosynthetic performance, and the relative water content of plants. SiNP100 treatment significantly improved photosynthesis (up to 72.7% increase), chlorophyll contents, and relative water content (up to 63% increase), but decreased oxidative damage, which collectively contributed to increased plant growth. Moreover, the application of SiNP100 on drought-stressed ginger has the potential to maintain stomatal opening and increase stomatal density through increasing leaf water potential and maintaining leaf cell integrity. The increased leaf osmotic potential (up to 35.1% increase) and leaf water potential (up to 3.6% increase) may further promote the accumulation of ABA in ginger seedlings. Furthermore, SiNP100 increased root growth and root hydraulic conductance (Lp, up to 3.6% increase), which contribute to the increased root water uptake. Further results revealed that SiNP100 can regulate water balance of ginger plants under drought conditions by up-regulating the expression of ZoAQP genes, especially in the rhizome. Under drought stress, the exogenous application of HgCl₂ decreased the water loss transpiration rates of seedlings and SiNP100 alleviated this decrease. Therefore, this study can help to better understand the role of SiNP100 in alleviating drought stress and to further develop technologies for plants to counteract the influence of abiotic stress.