Five rootstocks for ‘Emperor’ mandarin under subtropical climate in Southern Brazil

Authors: CRUZ, MARIA - State University Of Londrina; NEVES, CARMEN - State University Of Londrina; DE CARVALHO, DEIVED - State University Of Londrina; COLOMBO, RONAN - Federal University Of Technology - Parana; Bai, Jinhe; YADA, INES - Federal University Of Technology - Parana; LEITE JR., RUI - Federal University Of Technology - Parana; TAZIMA, ZULEIDE - Federal University Of Technology - Parana

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/23/2021
Publication Date: 12/20/2021
Citation: Cruz, M., Neves, C., De Carvalho, D., Colombo, R., Bai, J., Yada, I., Leite Jr., R., Tazima, Z. 2021. Five rootstocks for ‘Emperor’ mandarin under subtropical climate in Southern Brazil. Frontiers in Plant Science. https://doi.org/10.3389/fpls.2021.777871.
DOI: https://doi.org/10.3389/fpls.2021.777871

Interpretive Summary: 'Emperor' has moderate resistance to citrus canker disease and is adapted to a wide edaphoclimatic conditions. ‘Rangpur’ lime (C. limonia Osbeck) has been the most common rootstock for citrus in Paraná, as it has good compatibility with most commercial scion cultivars. However, the susceptibility of the ‘Rangpur’ lime to some diseases, as citrus blight, citrus sudden death (CSD), and gummosis caused by Phytophthora spp., has raised concerns and the need for new alternative rootstocks. The objectives of this research were to compare four potential rootstocks with the commercial standard, 'Rangpur' lime for the productivity and disease resistance/tolarance. ‘Emperor’ mandarin trees grafted on ‘Rangpur’ lime had the smallest vegetative growth, while trees on ‘Swingle’ citrumelo and ‘Fepagro C-13’ citrange showed low scion/rootstock affinity without any clear sign of incompatibility. Trees on ‘Cleopatra’ and ‘Sunki’ mandarins, ‘Swingle’ citrumelo and ‘Fepagro C-13’ citrange rootstocks were comparable or superior to trees on ‘Rangpur’ lime in regard to yield performance and fruit quality under the subtropical climate of the Northern region of the state of Paraná, Brazil. Therefore, ‘Emperor’ mandarin grafted on all tested rootstocks showed highly desirable agronomic performance and can

Technical Abstract: Rootstocks modulate several characteristic of the citrus trees, including vegetative growth, fruit yield and quality, and resitance or tolerance to pest, disease, drought, and salinity, among other factors. ‘Ponkan’ mandarin grafted on ‘Rangpur’ lime comprises the majority of the commercial mandarin orchards in Brazil. Therefore, the low genetic diversity of citrus orchards can favor the pest and disease outbreaks. In this context, this study aimed to evaluate the agronomic performance and fruit quality of ‘Emperor’ mandarin on five different rootstocks for nine cropping seasons under the subtropical soil-climate conditions of the North region of the state of Paraná, Brazil. The experimental design was randomized block, with six replications, two trees per plot, and five treatments, including ‘Rangpur’ lime, ‘Cleopatra’ and ‘Sunki’ mandarins, ‘Swingle’ citrumelo, and ‘Fepagro C-13’ citrange. The evaluations consisted of tree growth, yield performance, fruit quality, and incidence of Huanglongbing (HLB) disease. ‘Emperor’ mandarin trees grafted on ‘Rangpur’ lime had the smallest growth while trees on ‘Swingle’ citrumelo and ‘Fepagro C-13’ citrange showed low scion and rootstock affinity, without clear incompatibility symptoms. The trees on ‘Cleopatra’ and ‘Sunki’ mandarins, ‘Swingle citrumelo, and ‘Fepagro C-13’ citrange were comparable or superior to those on ‘Rangpur’ lime in regard to yield performance and fruit quality. The trees of ‘Emperor’ mandarin were susceptible to HLB regardless the rootstocks they were grafted on. Overall, ‘Emperor’ mandarin trees grown on all tested rootstocks showed desirable agronomic performance and can be considered as a potential cultivar for new plantings under similar soil and climate conditions as the ones in the North region of the state of Paraná, Brazil.