Sorghum drought tolerance is enhanced by cerium oxide nanoparticles via stomatal regulation and osmolyte accumulation.

Sorghum [Sorghum bicolor (L.) Moench] yield is limited by the coincidence of drought during its sensitive stages. The use of cerium oxide nanoparticles in agriculture is minimal despite its antioxidant properties. We hypothesize that drought-induced decreases in photosynthetic rate in sorghum may be associated with decreased tissue water content and organelle membrane damage. We aimed to quantify the impact of foliar application of nanoceria on transpiration rate, accumulation of compatible solutes, photosynthetic rate and reproductive success under drought stress in sorghum. In order to ascertain the mechanism by which nanoceria mitigate drought-induced inhibition of photosynthesis and reproductive success, experiments were undertaken in a factorial completely randomized design or split-plot design. Foliar spray of nanoceria under progressive soil drying conserved soil moisture by restricting the transpiration rate than water spray, indicating that nanoceria exerted strong stomatal control. Under drought stress at the seed development stage, foliar application of nanoceria at 25 mg L-1 significantly improved the photosynthetic rate (19%) compared to control by maintaining a higher tissue water content (18%) achieved by accumulating compatible solutes. The nanoceria-sprayed plants exhibited intact chloroplast and thylakoid membranes because of increased heme enzymes [catalase (53%) and peroxidase (45%)] activity, which helped in the reduction of hydrogen peroxide content (74%). Under drought, compared to water spray, nanoceria improved the seed-set percentage (24%) and individual seed mass (27%), eventually causing a higher seed yield. Thus, foliar application of nanoceria at 25 mg L-1 under drought can increase grain yield through increased photosynthesis and reproductive traits.

Nanocatalytic Interface to Decode the Phytovolatile Language for Latent Crop Diagnosis in Future Farms.

Crop diseases cause the release of volatiles. Here, the use of an SnO2-based chemoresistive sensor for early diagnosis has been attempted. Ionone is one of the signature volatiles released by the enzymatic and nonenzymatic cleavage of carotene at the latent stage of some biotic stresses. To our knowledge, this is the first attempt at sensing volatiles with multiple oxidation sites, i.e., ionone (4 oxidation sites), from the phytovolatile library, to derive stronger signals at minimum concentrations. Further, the sensitivity was enhanced on an interdigitated electrode by the addition of platinum as the dopant for a favorable space charge layer and for surface island formation for reactive interface sites. The mechanistic influence of oxygen vacancy formation was studied through detailed density functional theory (DFT) calculations and reactive oxygen-assisted enhanced binding through X-ray photoelectron spectroscopy (XPS) analysis.