Biochemical and anatomical aspects of copper deficiency induced by high nitrogen supply in Citrus

Author(s)

Mattos-Jr, D. ; Huber, L. N. ; Petena, G. ; Bortoloti, G. A. ; Hippler, F. W. R. ; Boaretto, R. M.

• Document type: Journal article
• Source: PLANT AND SOIL; v. N/A, p. 12-pg., 2023-02-06.

Abstract

Aims Copper (Cu) is essential for enzymatic systems, electron transport during photosynthesis, and lignin synthesis, affecting plant metabolism and growth. Cu deficiency is observed in young tree orchards, possibly induced by interaction with other mineral nutrients, although visual symptoms are not easily characterized. This study evaluated the induction of Cu deficiency in citrus, due to high nitrogen (N) fertilization, based on the assessment of biochemical parameters, gas exchange, and anatomy of plant tissues.Methods Valencia orange trees were submitted to levels of Cu supply via fertigation in addition to foliar spraying (control without Cu or with 2.4 g plant(-1) of Cu), and N (medium = 8.6 or high = 25.9 g plant(-1) of N) for 210 days.Results Plants well supplied with Cu exhibited higher electron transport rate, net CO2 assimilation, transpiration, and stomatal conductance, in comparison to the control without Cu. Those grown with high N exhibited greater electron transport rate compared to medium N. Plants without Cu and high N supply exhibited the lowest nitrate reductase activity, whereas plants fertilized with Cu and high N exhibited the greatest increase in the activity of this enzyme, in addition to the highest levels of total free amino acids. Furthermore, plants without Cu and high N exhibited the lowest Cu/Zn-SOD II isoform activity. Loose parenchyma structures of leaves and branches were associated with visual symptoms of Cu deficiency.Conclusion Plant responses demonstrated how Cu deficiency is induced in citrus trees by excess N, thus highlighting the importance of establishing best nutrient management for sustainable fruit production. (AU)

• FAPESP's process: 12/13917-7 - Copper deficiency and toxicity in Citrus: integrating nutrient absorption and plant nutritional status
• Grantee: Franz Walter Rieger Hippler
• Support Opportunities: Scholarships in Brazil - Doctorate