Zinc oxide nanoparticles alleviate drought-induced alterations in sorghum performance, nutrient acquisition, and grain fortification

• Published in: The Science of the total environment Vol. 688; pp. 926 - 934
• Main Authors: Dimkpa, Christian O., Singh, Upendra, Bindraban, Prem S., Elmer, Wade H., Gardea-Torresdey, Jorge L., White, Jason C.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 20-10-2019
• Subjects: Drought stress; Droughts; Edible Grain; Fertilizers; Food and nutrition security; Nanoparticles - metabolism; Nitrogen - metabolism; Nutrient use efficiency; Phosphorus - metabolism; Resilient agriculture; Sorghum - physiology; Zinc Oxide - metabolism; Zinc oxide nanoparticles; Drought stress; Food and nutrition security; Nutrient use efficiency; Resilient agriculture; Zinc oxide nanoparticles
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2019.06.392

Drought is a major environmental event affecting crop productivity and nutritional quality, and potentially, human nutrition. This study evaluated drought effects on performance and nutrient acquisition and distribution in sorghum; and whether ZnO nanoparticles (ZnO-NPs) might alleviate such effects. Soil was amended with ZnO-NPs at 1, 3, and 5 mg Zn/kg, and drought was imposed 4 weeks after seed germination by maintaining the soil at 40% of field moisture capacity. Flag leaf and grain head emergence were delayed 6–17 days by drought, but the delays were reduced to 4–5 days by ZnO-NPs. Drought significantly (p < 0.05) reduced (76%) grain yield; however, ZnO-NP amendment under drought improved grain (22–183%) yield. Drought inhibited grain nitrogen (N) translocation (57%) and total (root, shoot and grain) N acquisition (22%). However, ZnO-NPs (5 mg/kg) improved (84%) grain N translocation relative to the drought control and restored total N levels to the non-drought condition. Shoot uptake of phosphorus (P) was promoted (39%) by drought, while grain P translocation was inhibited (63%); however, ZnO-NPs lowered total P acquisition under drought by 11–23%. Drought impeded shoot uptake (45%), grain translocation (71%) and total acquisition (41%) of potassium (K). ZnO-NP amendment (5 mg/kg) to drought-affected plants improved total K acquisition (16–30%) and grain K (123%), relative to the drought control. Drought lowered (32%) average grain Zn concentration; however, ZnO-NP amendments improved (94%) grain Zn under drought. This study represents the first evidence of mitigation of drought stress in full-term plants solely by exposure to ZnO-NPs in soil. The ability of ZnO-NPs to accelerate plant development, promote yield, fortify edible grains with critically essential nutrients such as Zn, and improve N acquisition under drought stress has strong implications for increasing cropping systems resilience, sustaining human/animal food/feed and nutrition security, and reducing nutrient losses and environmental pollution associated with N-fertilizers.
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•Nano ZnO (ZnO NP) alleviation of drought effects in plants was evaluated in soil.•Drought inhibited plant development, yield and nutrient accumulation.•ZnO NP improved plant development and yield under drought.•ZnO NP improved plant nitrogen, potassium and zinc contents under drought stress.•Results have implications for crop production, nutrient management and human health.