Biomass partitioning and photosynthesis in the quest for nitrogen- use efficiency for citrus tree species.

Optimizing the use of nitrogen (N) for food production is a major challenge in agricultural systems. The transformation of N into crop production results from intricate pathways, depending on plants, as well as the environment and fertilization regimes, which affect the N-use efficiency (NUE) of plants. In this context, lemon trees [Citrus limon (L.

Photosynthesis is differently regulated during and after copper-induced nutritional stress in citrus trees.

Antioxidant enzymatic responses in Citrus leaves under Cu-induced stress depends on rootstock genotypes. However, there is a lack of information about how woody plants recover growth capacity after exposure to elevated Cu and whether growth is affected by the redistribution of the metal to new vegetative parts and consequently whether photosynthesis is affected. Therefore, the biomass of plants and Cu concentrations in new leaf flushes were determined in young citrus trees grafted onto contrasting rootstocks [Swingle citrumelo (SW) and Rangpur lime (RL)].

Oxidative stress induced by Cu nutritional disorders in Citrus depends on nitrogen and calcium availability.

Nutritional stress caused by copper (Cu) deficiency or toxicity affects fruit production of citrus orchards worldwide, but this could be minimised by fine-tuned fertilisation in the orchards. Two experiments were performed aiming to evaluate the photosynthetic capacity and the antioxidant enzyme activities of Swingle citrumelo seedlings, grown in nutrient solution (NS) with two levels of nitrogen (N) in the first experiment (adequate-N and high-N) and two levels of calcium (Ca) in the second (low-Ca and adequate-Ca). Plants were then exposed to various Cu levels (low, medium and high) for 15 days.