Nutrient deficiency lowers photochemical and carboxylation efficiency in tobacco

Nutritional deficiency in plants triggers significant economic losses for important crops. As a direct consequence, it broadly affects plant growth, and photosynthetic efficiency is strongly influenced by nutritional imbalance. To deepen our understanding of how nutritional deficiencies affects photosynthesis, we removed the supply of macronutrients (N, P, K, Ca, S) one element at a time at hydroponic tobacco cultivation. Essential macronutrient deficiencies affected both photochemical and carboxylative steps of photosynthesis. In addition, interference on light absorption, energy quenching and the electron transport chain influenced carbon reactions. In particular, deficiencies in N and S depleted potential CO 2 assimilation, while Ca deficiency affected CO 2 diffusion (mainly g s ), and light reactions were affected as well. P deficiency promoted severe damage to the antenna complexes and reaction centres of the photosystems. All deficiencies increased energy dissipation (ɸDo) and nonphotochemical dissipation (Kn). Reduction of ETR and probability of electron transport of QA − for plastoquinone (ΨEo and ɸEo) following distinct levels of damages to ETC were observed.