Physiological and biochemical performance of lettuce ('Lactuca sativa' L.) seeds treated with essential oils used to control phytopathogens

• Published in: Australian Journal of Crop Science Vol. 16; no. 3; pp. 329 - S1
• Main Authors: Vismara, Lilian de Souza, Siega, Thayllane de Campos, Bertoldo, Edson, Mazaro, Sérgio Miguel, Vismara, Edgar de Souza, Rey, Maristela dos Santos, Moraes, Pedro Valério Dutra
• Format: Journal Article
• Language: English
• Published: Lismore, N.S.W Southern Cross Publishers 01.03.2022
• Subjects: Allelopathy; Control; Evaluation; Lettuce; Patchouli oil; Plant extracts; Seed-borne phytopathogens
• ISSN: 1835-2693; 1835-2707
• DOI: 10.21475/AJCS.22.16.03.P2874

This work aimed to evaluate the physiological and biochemical performance of lettuce ('Lactuca sativa' L.) seeds treated with essential oils (EOs) of citronella ('Cymbopogon' sp.), guacatonga ('Casearia sylvestris' Sw.), melaleuca ('Melaleuca' sp. L.), patchouli ('Pogostemon' sp. Benth), and pitangueira ('Eugenia uniflora' L.). The experimental design was completely randomized in double factorials (5 oils × 4 doses) at different doses (10, 20, 30, and 40 muL), with an additional treatment that served as growth control (without EOs, 0 muL). In other words, the experimental design entails 5 oils × 4 doses + 1 control, with 4 replicates of 100 Grand Rapid lettuce seeds without industrial chemical treatment. The response variables were: first germination count (FGC, %), last germination count (LGC, %), germination rate (GR), normal seedlings (NS, %), abnormal seedlings (AS, %), aerial part length (APL, cm), fresh mass (mf, g), total soluble proteins content (mg·g-1), and enzyme activities of beta-1,3-glucanase (UA·mg-1) and phenylalanine ammonia-lyase (PAL, UA·mg-1). The lettuce plant proved to be a good reference plant for evaluations related to physiological and biochemical performance when treated with EOs. However, although treatment of lettuce seeds with EOs did not cause undesirable damages, it positively altered the physiological parameters APL and mf. All EOs affected the total proteins content and enzyme activities of PAL and beta-1,3-glucanase. Therefore, EOs demonstrated the potential to activate the plant's defense mechanism to control phytopathogens. More specifically, 10 muL of citronella EO activated two plant defense mechanisms: PAL and beta-1,3-glucanase activities. In addition, EOs of melaleuca (10 and 40 muL) and patchouli (20 and 30 muL) also activated PAL enzyme activity.