Effects of nutrient supply on photosynthetic acclimation and photoinhibition of one-year-old foliage of Picea abies

The present study examined the effect of nutrient supply on acclimation potential and photoinhibitory susceptibility in one-year-old foliage of shade-grown Norway spruce ( Picea abies Karst.) seedlings transferred to high-light, as compared to seedlings grown in shade or in high-light. After the transfer, the photosynthetic response to intercellular CO₂ and chlorophyll fluorescence parameters were measured, and the allocation of leaf N within the photosynthetic apparatus was estimated. The effects of light and nutrient supply markedly differed. Light availability positively affected both photosynthetic capacity on an area basis (but not on a mass basis) and leaf N allocation to ribulose-1,5-biphosphate carboxylase/oxygenase (Rubisco), thereby increasing photosynthetic capacity per unit nitrogen. By contrast, nutrient supply in high-light affected photosynthetic capacity both on an area and a mass basis, but did not affect the allocation of N within the photosynthetic apparatus. Fluorescence parameters indicated that shade-grown seedlings transferred to high-light with low-nutrient supply, underwent prolonged photoinhibition. By contrast, transferred seedlings with high-nutrient supply were able to avoid photoinhibition, increasing their photosynthetic capacity on an area basis. On the whole, nutrient shortage was found to prevent the acclimation response and to increase the photoinhibitory susceptibility to changing light conditions in P. abies mature needles.