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.

The use of cover crops has proved to be a promising strategy in soil decompaction. Thus, the objective was to evaluate the morphophysiological characteristics of maize plants ( Zea mays L.), Urochloa ruziziensis and Panicum maximum growing in soil with or without subsurface compaction. The experiment was conducted in a greenhouse, adopting the factorial scheme 4 x 2, being three cover crops (single corn, U. ruziziensis, P. maximum - BRS Zuri) and a corn-U. ruziziensis intercrop grown in soil with and without compaction in the layer of 10-15 cm of depth, with four replications. Physiological and morphological variables and dry matter accumulation of roots and shoots were evaluated. Subsurface compaction reduced the shoot dry mass of U. ruziziensis, corn-U. ruziziensis and single corn. The U. ruziziensis and single corn plants had a reduction in the dry mass of roots in different layers of depth and in conditions of subsurface compaction. The U. ruziziensis and P. maximum grasses showed higher photosynthetic rate when growing in compacted soil. Corn was the species most sensitive to subsurface compaction, showing the greatest reduction in physiological parameters and biomass accumulation. The corn-U. ruziziensis intercrop minimizes the damage of soil compaction to maize plants. P. maximum grass is a promising species to be cultivated in compacted soils, as it demonstrates good adaptability and resistance to this condition; the U. ruziziensis is an efficient species in soils without subsurface compaction.