Aluminum-induced decrease in CO2 assimilation in 'Rangpur' lime is associated with low stomatal conductance rather than low photochemical performances

Author(s)

Banhos, Otavia F. A. A. ; Carvalho, Brenda M. de O. ; da Veiga, Eduardo B. ; Bressan, Anna C. G. ; Tanaka, Francisco A. O. ; Habermann, Gustavo

• Document type: Journal article
• Source: Scientia Horticulturae; v. 205, p. 8-pg., 2016-06-23.

Abstract

Aluminum (Al) is toxic to most plants. Although inhibition of root elongation can occur even under 10 mu M Al, above 1000 mu M damage to photochemical performances has been reported, reducing the CO2 assimilation rate (A). However, Al is retained in the roots of most plants, including Citrus limonia ('Rangpur' lime) with no direct explanation for the low A. In this study, 'Rangpur' lime plants were cultivated hydroponically in a nutrient solution with 1480 mu M Al, and we expected to determine the time range within which Al-induced decrease in A starts. To our surprise, low stomata( conductance (gs) rather than low photochemical performances was evident 45 days after exposing the roots to Al. Aluminum was mostly retained in the roots and histochemically observed in the stele, suggesting reduction in water uptake/transport in the xylem that became fibrous. We also found a 35% reduction in the midday leaf water potential in plants exposed to Al, indicating association between the fibrous xylem vessels and low gs, which could explain the Al-induced decrease in A in 'Rangpur' lime plants. (C) 2016 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 12/01351-9 - Study of Cerrado native species as a resource for the overcoming of aluminum toxicity in agriculture
• Grantee: Gustavo Habermann
• Support Opportunities: Regular Research Grants