Regulation of Nutrient Assimilation by Plant Hormones and Its Relation to Crop Yields

Phytohormones play a central role in regulating nutrient uptake, transport, and assimilation through complex signaling networks that integrate environmental and developmental cues. Hormones such as auxins, cytokinins, gibberellins, abscisic acid, ethylene, and more recently identified molecules like strigolactones and brassinosteroids coordinate the expression of genes and the activity of transporters involved in nitrogen (N), phosphorus (P), potassium (K), and micronutrient homeostasis. Auxins modulate root architecture, enhancing surface area for nutrient acquisition, while cytokinins influence nutrient remobilization and signaling under nutrient-sufficient or nutrient-deficient conditions. Gibberellins stimulate root elongation and nutrient transporter expression, whereas abscisic acid (ABA) is pivotal during stress conditions, modulating stomatal closure and nutrient allocation. Strigolactones and brassinosteroids act as fine-tuners of root development and nutrient signaling, ensuring balanced growth under fluctuating nutrient environments. The hormone-mediated regulation of nutrient assimilation directly impacts crop yield by affecting photosynthesis, biomass accumulation, reproductive success, and grain filling. For instance, optimal nitrogen uptake, largely influenced by cytokinin and nitrate signaling, leads to higher chlorophyll content and photosynthetic rates. Similarly, phosphorus acquisition is enhanced by hormonal regulation of mycorrhizal interactions and root hair proliferation. Recent biotechnological and agronomic advances aim to manipulate hormone pathways to improve nutrient use efficiency (NUE), reduce fertilizer dependency, and enhance crop productivity in sustainable ways. Understanding the interplay between plant hormones and nutrient assimilation provides critical insights for developing climate-resilient, high-yielding crops adapted to varying soil fertility conditions.