Artificial rainfall patterns alter non-structural carbohydrate allocation to modulate growth and eco-stoichiometry in...

Cyphomandra betacea, a valuable understory crop in southwestern China, exhibits high sensitivity to water availability. Under global climate change with increasingly erratic precipitation, understanding how Cyphomandra betacea, seedlings respond to rainfall variations is crucial for sustaining this distinctive industry. Through controlled experiments, this work systematically investigates how different rainfall patterns affect seedling growth and physiology, providing a theoretical basis for science-based management under future climate scenarios. Seedlings were subjected to a four-month simulated rainfall experiment with two rainfall intervals (T: 3-day; T₊: 6-day) and three rainfall amounts (W: control; W₊: +40%; W_-: -40%). Biomass, non-structural carbohydrates (NSC), and carbon, nitrogen, phosphorus stoichiometric characteristics were analysed. Seedling growth is more sensitive to variations in rainfall amount, and appropriate increases in rainfall can promote seedling growth and development. Under changes in rainfall patterns, seedlings prioritize the storage of NSC in stems, followed by leaves, with the lowest allocation to roots. Nitrogen content within organs is pivotal for the composition of NSC and can regulate the sugar-starch conversion process. The July W₊T treatment resulted in optimal performance for the majority of growth indicators and demonstrated the highest nutrient accumulation efficiency. We identified a stem-preferential carbon allocation strategy and systemic N limitation, offering key insights for conservation and cultivation under changing climates.