ABSTRACT The search for bioherbicides has been encouraged, and plants used in food or with bioactivity have been studied. Therefore, this article aimed to investigate the bioherbicidal potential of essential oils from Psidium cauliflorum and P. acidum through a plant toxicity bioassay using Lactuca sativa and Sorghum bicolor. The seeds were treated with essential oils of both species, along with control groups treated with distilled water, dichloromethane, and glyphosate. Germination percentage (GP), germination speed index (GSI), root growth (RG), shoot length (SL), mitotic index (MI), chromosomal alterations (CA), and nuclear alterations (NA) were evaluated. The major compound of the essential oil of P. cauliflorum was α-pinene, and of P. acidum were trans-caryophyllene, β-elemene, germacrene A, and α-copaene. The essential oils from both species exhibited phytotoxic effects. P. acidum oil inhibited sorghum RG and lettuce SL, while P. cauliflorum oil reduced GP, GSI, RG, and SL in both plants, indicating higher phytotoxicity than P. acidum and non-selective behavior. Cytotoxic investigations showed that both oils inhibited the MI. CA analysis revealed that P. cauliflorum oil exhibited aneugenic and clastogenic action mechanisms. The results demonstrate the bioherbicidal potential of P. cauliflorum essential oil, in addition to being non-selective and displaying a similar inhibition rate to glyphosate.

RESUMO O gênero Psidium é reconhecido pelo seu valor econômico e por suas espécies produtoras de óleos essenciais, com notáveis atividades biológicas. Este estudo investigou as características do óleo essencial das folhas de Psidium myrtoides e Psidium cattleyanum sob diferentes temperaturas de secagem. O objetivo foi entender como as temperaturas de secagem afetam o rendimento e a composição do óleo essencial, além de sua atividade biológica, utilizando bioensaios com Lactuca sativa e Sorghum bicolor para avaliar os efeitos fitotóxicos. Os óleos obtidos das folhas de P. myrtoides e P. cattleyanum secas em estufa a 40°C apresentaram os maiores rendimentos, sendo 0,86% e 1,07%, respectivamente. O β-cariofileno foi o composto majoritário com maior área relativa em todos os óleos essenciais de P. myrtoides e P. cattleyanum, exceto, no óleo extraído de folhas secas em temperatura ambiente de P. myrtoides, cujo composto majoritário foi o alfa-bisabolol (14,46%). Assim como a alteração do perfil químico dos óleos essenciais, houve diferentes efeitos fitotóxicos utilizando a emulsão desses óleos. Esses efeitos, foram associados a composição química e a sinergia destes compostos. A emulsão de óleo essencial de folhas secas à temperatura ambiente de ambas as espécies mostrou maior atividade fitotóxica nos bioensaios. Assim, a otimização das condições de secagem para maximizar o rendimento e a sinergia dos compostos dos óleos essenciais de P. myrtoides e P. cattleyanum é um passo importante no desenvolvimento de agroquímicos naturais e sustentáveis. biológicas biológica P 40C C 40 rendimentos 086 0 86 0,86 107 1 07 1,07% respectivamente βcariofileno β cariofileno exceto alfabisabolol alfa bisabolol 14,46%. 1446 14,46% . 14 46 (14,46%) sustentáveis 4 08 8 0,8 10 1,07 144 14,46 (14,46% 0, 1,0 14,4 (14,46 1, 14, (14,4 (14, (14 (1 (

ABSTRACT The genus Psidium is recognized for its economic value and the species that produce essential oils with notable biological activities. This study investigated the characteristics of the essential oil from the leaves of Psidium myrtoides and Psidium cattleyanum under different drying temperatures. We aimed to understand how drying temperatures affect the yield and composition of the essential oil, as well as its biological activity. The oils obtained from the leaves of P. myrtoides and P. cattleyanum dried in an oven at 40°C showed the highest yields (0.86% and 1.07%, respectively). β-caryophyllene was the major compound in all essential oils of P. myrtoides and P. cattleyanum, except in the oil extracted from P. myrtoides leaves dried at room temperature, where the major compound was α-bisabolol (14.46%). Different phytotoxic effects were observed using the emulsion of these oils in bioassays with Lactuca sativa and Sorghum bicolor, which were associated with the chemical composition and synergy of the identified compounds. The essential oil emulsion from leaves dried at room temperature of both species showed greater phytotoxic activity in the bioassays. Thus, optimizing drying conditions to maximize yield and synergy of compounds from the essential oils of P. myrtoides and P. cattleyanum is an important step in developing environmentally friendly natural agrochemicals. activities P 40C C 40 0.86% 086 0 86 (0.86 107 1 07 1.07% respectively. respectively . respectively) βcaryophyllene β caryophyllene αbisabolol α bisabolol 14.46%. 1446 14.46% 14 46 (14.46%) bicolor Thus agrochemicals 4 0.86 08 8 (0.8 10 1.07 144 14.46 (14.46% 0.8 (0. 1.0 14.4 (14.46 0. (0 1. 14. (14.4 ( (14. (14 (1

ABSTRACT The essential oil of Piper amalago L. is recognized for its bioactive compounds with phytotoxic potential against invasive plants. However, little is known about the role of seasonal variation in the action of these compounds. This study aimed to investigate the impact of dry and rainy seasons on the chemical composition, phytotoxic, and cytogenotoxic activity of P. amalago essential oil. Analysis of the chemical composition revealed qualitative and quantitative variations, highlighting β-elemene, germacrene A, linalool, and β-caryophyllene as major compounds. The essential oil from the rainy season showed higher yield compared to that of the dry season. In pre-emergence tests against Bidens pilosa (invasive plant) and Lactuca sativa (non-target plant), negative effects on germination and root and shoot growth were observed, with these effects being more pronounced at higher concentrations, resembling the herbicide glyphosate. The essential oil from the dry season exhibited greater phytotoxic activity on the germination and development of the aerial part of B. pilosa, associated with higher concentrations of linalool and caryophyllene oxide. Additionally, the essential oils of P. amalago induced changes in the mitotic index and aneugenic alterations in L. sativa meristematic cells. These results underscore the bioherbicidal potential of P. amalago essential oil, highlighting its greater efficacy against B. pilosa during the dry season, possibly due to higher levels of linalool and caryophyllene oxide. L plants However P variations βelemene, βelemene β elemene, elemene β-elemene A βcaryophyllene preemergence pre emergence plant nontarget non target plant, , observed glyphosate B oxide Additionally cells

Abstract We investigated whether essential oil and aqueous and ethanolic extracts from M. vittoriana leaves have phytotoxic effects on the germination and initial development, and cytogenotoxic effects on the cell cycle, of model plants. The essential oil and extracts of M. vittoriana were characterized and used as treatments in phytotoxicity and cytotoxicity tests. The results indicated a reduction in germinative parameters and plant growth, with the higher concentrations of extracts and essential oil having the most evident effects. The cell cycle was also affected with a reduction of the mitotic index and the presence of chromosomal and nuclear alterations. All treatments showed clastogenic and aneugenic modes of action. The results can be associated with the synergistic effects of metabolites found in the extracts and essential oil, mainly the presence of the sesquiterpene germacrene D in the essential oil and of catechins, saponins, and tannins in the extracts. These substances inhibit plant germination and growth, confirming the phytotoxic effects of M. vittoriana in plant models, which should now be tested under field conditions.