Physiological and growth responses of Chinese chives (Allium tuberosum) to elevated CO2 concentrations and infestation by fungus gnat (Bradysia impatiens)

Elevated CO₂ (eCO₂) levels can alter plant physiology by reducing stomatal density, weakening transpiration, enhancing photosynthesis, accelerating growth, increasing the carbon-to-nitrogen ratio, and lowering nitrogen content. This study investigated the combined effects of eCO₂ stress and Bradysia impatiens infestation on Chinese chive (Allium tuberosum) under controlled CO₂ growth chamber conditions. A factorial experimental design was implemented, incorporating two CO₂ concentration levels and three fungus gnat infestation intensities. The results revealed significant increases in leaf width, leaf thickness, soluble sugar and chlorophyll b levels in Chinese chive plants under both eCO₂ and ambient CO₂ (aCO₂) conditions, irrespective of B. impatiens infestation status. Conversely, soluble protein content, chlorophyll a, and total chlorophyll concentrations showed significant reductions under both CO₂ regimes, regardless of B. impatiens infestation. These findings demonstrate that the growth and physiological responses of Chinese chive are substantially influenced by insect infestation under projected eCO₂ scenarios. This research provides valuable insights for developing adaptive strategies against B. impatiens infestations in the context of atmospheric change, contributing to sustainable agricultural practices under future climate conditions.