A greener tomorrow: How nanoparticles are helping plants fight environmental stress
The agricultural sector faces major challenges from climate change, such as increasing temperatures, unpredictable rainfall and soil degradation, all of which jeopardise food security for a rapidly growing global population. Abiotic stresses such as drought, salinity, extreme temperatures and heavy metal contamination account for major crop losses, with drought alone responsible for approximately 70 per cent of potential losses. These stressors disrupt seed germination, root growth and photosynthesis, leading to oxidative damage from reactive oxygen species (ROS) – highly reactive molecules that can harm plant cells and impair growth.
Nanotechnology, which manipulates matter at the nanoscale (1-to-100 nanometres), offers promising solutions. Nanoparticles possess distinct characteristics. These include a high surface area-to-volume ratio and increased reactivity, which bolsters plant defences against abiotic stress. By affecting physiological, biochemical and molecular processes, nanoparticles can enhance plant resilience and productivity.
Here’s how diverse types of nanoparticles help plants combat specific stressors:
Drought stress mitigation
Nanoparticles play a crucial role in enhancing plant tolerance to drought conditions:
· Iron oxide nanoparticles enhance chlorophyll content and soluble sugar levels in drought-stressed plants, improving production of photo-assimilates (the products of photosynthesis).
· Foliar-applied selenium nanoparticles reduce ionic leakage and lipid peroxidation, minimising cellular damage from drought.
· Silica nanoparticles strengthen cell walls, enhance lodging tolerance and aid osmotic adjustment, improving seed germination, seedling weight and plant growth under drought.
Salinity stress alleviation
Nanoparticles have demonstrated significant potential in helping plants cope with saline stress:
· Low doses of silver nanoparticles boost root growth and plant health under saline conditions by reducing oxidative stress and regulating proline metabolism.
· Zinc oxide nanoparticles enhance stress tolerance by improving physiological traits, enhancing gene expression related to stress tolerance and increasing Zn levels in plants.
· Gold nanoparticles improve seed output and germination by influencing microRNA expression linked to stress response.
Temperature stress management
Nanoparticles have shown promise in helping plants cope with heat and cold stress:
· Foliar application of zinc oxide nanoparticles alleviates heat stress by boosting antioxidants and osmolytes. This improves chlorophyll content, gas exchange and grain yield while reducing ROS and lipid peroxidation.
· Titanium dioxide nanoparticles enhance photosynthetic and energy metabolism gene expression, improving membrane stability and photosynthesis under cold stress.
Heavy metal stress mitigation
Nanoparticles offer innovative solutions for plants growing in heavy metal-contaminated soils:
· Calcium oxide nanoparticles reduce arsenic toxicity by lowering arsenic transporter gene expression, enhancing calcium uptake and improving ROS scavenging.
· Biogenic copper nanoparticles synthesised from Shigella flexneri reduce cadmium translocation by increasing biomass and nutrient acquisition.
· Silica nanoparticles protect against heavy metal toxicity by enhancing grain weight and increasing biomass and mineral uptake, while reducing the expression of genes responsible for cadmium transport.
The role of antioxidants and phytohormones
A key mechanism by which nanoparticles enhance plant stress tolerance is through the modulation of antioxidant systems and phytohormone activity:
· Antioxidant Enhancement: Nanoparticles boost antioxidant enzyme activity (superoxide dismutase [SOD], catalase [CAT], peroxidase), helping plants manage oxidative stress caused by reactive oxygen species (ROS).
· Phytohormone Regulation: Nanoparticles influence the activity of vital plant hormones (abscisic acid [ABA], gibberellins [GA]) to enhance stress responses.
Nano-fertilisers: A dual approach to nutrition and stress tolerance
Nano-fertilisers represent a significant advancement in agricultural technology. They offer the dual benefit of improved nutrient delivery and enhanced stress tolerance.
· CeO2 nanoparticles improve root anatomy and photosynthesis, increasing salt stress tolerance in Brassica napus.
· Nano-fertilisers combined with organic amendments, like iron oxide nanoparticles with salicylic acid, can further improve stress resilience, such as mitigating drought effects in strawberry plants.
Nanotechnology advancements for crop resilience in India
India’s nanotechnology revolution is enhancing agricultural resilience. Indian Council of Agricultural Research (ICAR) and Indian Farmers Fertiliser Cooperative (IFFCO) lead the way with nano-fertilisers like Nano-urea and Nano-DAP, improving nutrient uptake and stress tolerance. Startups like Bio Prime Agri Solutions are also contributing with innovative technology such as SNIPR (Smart Nanomolecules Induced Physiological Response). These advancements are crucial for addressing drought, salinity and other environmental challenges facing Indian agriculture.
Conclusion: A nano-enabled green revolution
Nanotechnology offers a promising solution for sustainable agriculture in the face of climate change. By enhancing plant stress tolerance, nanoparticles enable crops and plants to be drought-resistant and thrive in saline or contaminated soil. As research advances, we are on the verge of a new green revolution, leveraging nanotechnology to tackle global food security and environmental challenges. With innovations like nanoparticle-enhanced crops, we are making significant strides toward a sustainable, resilient and productive farming future that can nourish the world while preserving the planet for future generations.
The author is senior research analyst, technology research & advisory, Aranca