Photosynthesis and Nitrogen Metabolism of Nepenthes alata in Response to Inorganic N O 3 - and Organic Prey N in the Greenhouse

Abstract

This study investigates the relative importance of leaf carnivory on Nepenthes alata by studying the effect of different nitrogen (N) sources on its photosynthesis and N metabolism in the greenhouse. Plants were given either inorganic N O 3 - , organic N derived from meal worms, Tenebrio molitor , or both N O 3 - and organic N for a period of four weeks. Leaf lamina (defined as leaves) had significant higher photosynthetic pigments and light saturation for photosynthesis compared to that of modified leaves (defined as pitchers). Maximal light saturated photosynthetic rates ( P max ) were higher in leaves than in pitchers. Leaves also had a higher light utilization than that of pitchers. Both leaves and pitchers of plants that were supplied with both inorganic N O 3 - and organic prey N had a similar photosynthetic capacity and N metabolism compared to plants that were given only inorganic N O 3 - . However, adding organic prey N to the pitchers enhanced both photosynthetic capacity and N metabolism when plants were grown under N O 3 - deprivation condition. These findings suggest that organic prey N is essential for N. alata to achieve higher photosynthetic capacity and N metabolism only when plants are subjected to an environment where inorganic N is scarce.