Interference of aluminum in leaf hydration in Citrus x limonia and in photosynthetic perfomance in Ilex paraguariensis and Qualea grandiflora

Author(s)

Giselle Schwab Silva

• Document type: Doctoral Thesis
• Press: Rio Claro. 2022-10-31.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências. Rio Claro
• Defense date: 2022-09-30
• Advisor: Gustavo Habermann; Marina Alves Gavassi

Abstract

In sensitive plants, inhibition of root elongation is the first symptom of Al toxicity. This inhibition has been associated with low leaf hydration, with negative consequences for leaf gas exchange, including stomatal conductance (gs). On the other hand, some plants are able to grow well on acidic soils with high Al available, and some of this species accumulating high Al in their tissues (Al-accumulators), without showing toxicity symptoms. Therefore, in the present work, to test different hypotheses in relation to Al, we used tree different species, a sensitive to Al (Citrus x limonia), a tolerant to Al (Ilex paraguariensis) and an Al accumulator (Qualea grandiflora). All the experiments were realized for 60 days in the nutrient solution. Plants of C. limonia were exposed to 0 and 1480 M Al to evaluated whether low leaf hydration occur before or after the inhibition of root growth. Lower gs was observed after 3 days and was associated to a high concentration of abscisic acid (ABA) in leaves of plants exposed to Al. Root growth inhibition was evidenced at 30 days in plants exposed to Al and this occurred after hydric and hydraulic parameters are affect by Al. Plants of I. paraguariensis were exposed to 0, 500, 1000 and 1500 M Al to test whether Al improves growth with consequently increases in the photosynthetic performance in this specie. Improvements in biometric and biomass parameters were observed for plants exposed to 500 and 1000M Al in relation to those not exposed to Al. The absence of Al affects the root growth, that consequently reduced the leaf hydration and photosynthetic performance. Seedling of Q. grandiflora were exposed to 0, 740 and 1480 M Al to test whether the Al increase the carbon assimilation through enhanced apparent carboxylation efficiency of ribulose-1,5-biphosphate carboxylase/oxygenase (Rubisco). Plants exposed to both Al treatments showed new white roots, increased root biomass and apparent carboxylation efficiency was higher in these plants. However, this higher efficiency is more associated with better leaf hydration and gas exchange rates instead the direct effect of Al in Rubisco performance. On the Other hand, plants not exposed to Al showed no root growth, necrotic roots, and low gas exchange rates with decreased apparent carboxylation efficiency. (AU)

• FAPESP's process: 18/25658-2 - Aluminum interference in leaf hydration in citrus limonia and in photosynthetic performance of Vochysia tucanorum
• Grantee: Giselle Schwab Silva
• Support Opportunities: Scholarships in Brazil - Doctorate