About this Research Topic
Plants take up and use mineral nutrients mainly by roots, but abundant evidence has shown that nutrients can also be taken up by aerial plant parts (leaves, fruits and stems). Restricted root uptake may commonly occur because of transient decline or permanent limitation on soil nutrient availability due to multiple environmental or rhizosphere-related factors. Under such conditions, plants cannot meet their nutrient requirements, and foliar application may be an efficient tool to maintain an adequate crop nutrient status. In spite of the widespread use of foliar fertilizers in agriculture, variable crop responses to foliar applications of macro and micro nutrients have been reported. For instance, wide variations exist in nutrient delivery efficiency, translocation and distribution of nutrients in plant tissues, growth performance, and impacts on root nutrient uptake. The processes by which a nutrient solution applied to the foliage is ultimately utilized by the plant include foliar adsorption, cuticular penetration, uptake and absorption into the metabolically active cellular compartments in the leaf, then translocation and utilization of the absorbed nutrient by the plant(1). A foliar applied chemical may cross the plant leaf surface via the cuticle per se, along cuticular cracks or imperfections, or through modified epidermal structures such as stomata, trichomes or lenticels. The structure and chemistry of the plant surface will affect the bi-directional diffusion of substances between the plant, the leaf surface and the surrounding environment and hence the rate of uptake of foliar fertilizers(1). The fate of the nutrient once it has been absorbed through the leaf surface has received only scant attention and little is known about the relative efficacy and metabolic impact of foliar applied nutrients. Understanding the factors influencing the efficacy of foliar fertilizers is crucial if this technology is to be used to effectively satisfy plant nutrient demand when soil supply is inadequate, especially under biotic (pests and diseases) or abiotic (water stress, temperature, nutrient-deficiency soils) stresses.
Deposition of atmospheric aerosols is another phenomenon that occurs at the vegetative canopy where leaves of green plants are exposed to hydrated gas molecules and particles. For example, plants can absorb nutrients from atmospheric aerosols (such as gaseous/particulate compounds of reactive nitrogen and sulfur species) deposited onto leaves and other aerial plant parts. At the individual plant level, deposition of these compounds commonly has a very limited contribution to the total nutrient requirement. For the most plants investigated, the contribution of aerosol NO2-N to total plant nitrogen (N) was less than 5%, while for less than 30% of plants the contribution ranged from 5% to 10%. Plant species have differential responses to aerosol input and wide variations in resistance and absorption capacity and critical response thresholds exist between species. Uptake of atmospheric aerosols involves complex but poorly understood metabolic networks and regulatory processes.
This research topic focuses on the factors affecting the absorption and the physiological impacts of foliar fertilization or atmospheric deposition on plant productivity. We aim to highlight the mechanisms of foliar macro- and micro-nutrient delivery, their movement in leaves, formation and transport of nutrient complexes, metabolic pathways, physiological relationship between foliar nutrient application and plant stress resistance, and related processes. We welcome the following article types: Original Research, Review Article, General Commentary, Hypothesis & Theory, Methods, Opinion.
Footnote: (1) Foliar Fertilization, Scientific Principles and Field Practices by Victoria Fernandez, Thomas Sotiropoulos, and Patrick Brown,
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