Nitrogen improves plant cooling capacity under increased environmental temperature

PurposeAgricultural production is facing multiple challenges from global warming. Nitrogen (N) plays an essential role in high-temperature tolerance and crop yield, which may depend on leaf cooling capacity. However, the effects of nitrogen on the leaf temperature response and the regulatory mechanisms of leaf cooling capacity under increased environmental temperature are largely unknown.MethodsCurrently, we evaluated the effects of nitrogen on the dynamic change in leaf temperature and the balance between heat dissipation and absorption, which contributes to leaf cooling capacity.ResultsThe results showed that cucumber plant growth and transpiration rate significantly increased with N supply, while leaf temperature decreased. As the environmental temperature increased, the cucumber leaf temperature and leaf cooling capacity increased, and the leaf cooling capacity improved with the N supply. Leaf temperature was negatively correlated with transpiration rate, and the increased transpiration rate contributed to higher heat dissipation and leaf cooling capacity under a high nitrogen supply. Leaf water content and water potential increased with N supply, which resulted in higher leaf specific heat capacity and heat absorption. However, nitrogen-deficient plants increased the nonstructural carbon content (NSC), structural carbon content (SC), and NSC/SC ratio, thus increasing plant adaptation to environmental stresses.ConclusionsNitrogen supply improved leaf cooling capacity by increasing the leaf transpiration rate and specific heat capacity, thereby regulating the balance between heat dissipation and absorption. Improving leaf cooling capacity by N supply may be a new strategy to increase plant adaptation to increased environmental temperatures.