A study of the phytotoxic effects of the aerial parts of Senecio westermanii Dusén (Asteraceae) on Lactuca sativa L. and Allium cepa L. seeds

The objective of this study was to evaluate the effects of the ethanolic crude extracts and fractions of the species Senecio westermanii Dusén on Lactuca sativa L. (lettuce) and Allium cepa L. (onion) seeds. We assessed the germination, growth, root respiration and photosynthesis of the target species in Petri dishes (9.0 cm diameter) containing filter paper n°6. The study was conducted using 50 seeds per plate and held in 4 replicates per concentration of each sample. In the germination there was an inhibitory effect of fractions hexane (FH) and chloroform (FCl) at concentrations of 500 and 1000 µg/mL. There was a reduction in the radicle growth of lettuce by 14 to 24% and a reduction of hypocotilum by 14 to 28%. As for the radicle of the onion was up 74% reduction to the FCl and the coleoptile was 24 and 45% reduction for FH and FCl, respectively. Inhibitory effects in the root respiration of lettuce were detected in all the samples analyzed, with results ranging from 16 to 83%. For the seeds of A. cepa, there was an encouragement for the FCl and ethyl acetate fractions (FAE), with results ranging from 94 to 142% and 76 to 150%, respectively. With regard to the photosynthesis of L. sativa, there was no significant difference between the control, and as for the A. cepa, there was a strain in inhibition concentrations of 250 and 500 µg/mL, which ranged from 27 to 68%. The samples of S. westermanii caused changes in the target species and thus can be used as a natural herbicide.

Potencial fitotóxico com enfoque alelopático de Bauhinia ungulata L. sobre sementes e plântulas de alface e cebola / Phytotoxic potential with allelopathic focus of Bauhinia ungulata L. on seeds and seedlings of lettuce and onion

O presente trabalho avaliou o efeito do extrato etanólico e diferentes frações das folhas de Bauhinia ungulata L. sobre a germinação, crescimento, respiração e conteúdo de clorofila de plântulas de Lactuca sativa (alface) e Allium cepa (cebola). Sementes de alface e cebola foram mantidas em contato com solução das amostras e colocadas em câmara de germinação. Realizaram-se contagens diárias para avaliar a interferência sobre a germinação e crescimento, e verificou-se possíveis interferências sobre a respiração radicular e o conteúdo de clorofila total das folhas das plântulas. Não foi observada nenhuma interferência das amostras sobre a porcentagem de germinação e massa seca das duas espécies. Com relação ao IVG, houve um atraso da germinação das sementes de alface quando em contato com o EB. O crescimento radicular das duas espécies foi inibido principalmente pelas frações EB e FR, sem nenhuma interferência sobre o crescimento do hipocótilo da alface e estímulo do crescimento do coleóptilo da cebola. Redução nos teores de clorofila total da alface e aumento na cebola, assim como estímulo da respiração das raízes. Conclui-se que o extrato e as frações de Bauhinia ungulata L. apresentam compostos químicos com atividade fitotóxica sobre o desenvolvimento de plântulas de alface interferindo principalmente no crescimento radicular, teor de clorofila e respiração radicular das espécies avaliadas.

This study evaluated the effect of ethanol extract and different fractions of leaves of Bauhinia ungulata L. on germination, growth, respiration and chlorophyll content of seedlings of Lactuca sativa (lettuce) and Allium cepa (onion). Seeds of lettuce and onions were put in contact with the sample solution and placed in a germination chamber. Daily counts were carried out to assess the interference on the germination and growth, and it was possible interference on the root respiration and the total chlorophyll content of the leaves of the seedlings. No interference of the samples on the percentage of germination and dry mass of the two species was not observed. With respect to GVI, there was a delay of germination of lettuce seeds when in contact with the CE. Root growth of the two species was inhibited mainly by fractions CE and RF, without any interference on the growth of hypocotyl of lettuce and stimulating onion coleoptile growth. Reduction in total chlorophyll content of lettuce and onion increased, as well as stimulating the respiration of roots. It is concluded that the extract and the Bauhinia ungulata L. fractions have chemical compounds with phytotoxic activity on the development of lettuce seedlings interfering mainly on root growth, chlorophyll content and root respiration of species assessed.

Residues of Citrus sinensis (L) Osbeck as agents that cause a change in antioxidant defense in plants / Resíduos de Citrus sinensis (L) Osbeck como agentes que causam uma alteração na defesa antioxidante em plantas

This work aimed to verify the allelopathic potential of the extract of Citrus seeds, for the purpose of adding a sustainable value to the fruit seeds toward their use as industrial residues. The extract was obtained with a Soxhlet apparatus by using hexane, chloroform, and methanol as solvents. The hexane extract of the Citrus seeds primarily consisted of linoleic acid (36.6%), followed by α-linoleic acid (25.3%), oleic acid (17.8%), palmitic acid (9.7%), and estearic acid (3.3%). The analysis results indicate that the oil is similar to those used in the cosmetics and food industries and has an economic value from its industrial application. In addition, the use of the oil causes changes in the oxidant balance, germination, and growth of plants...

Este trabalho teve como objetivo verificar o potencial alelopático do extrato de sementes de Citrus, com o objetivo de agregar valor sustentável para a semente de frutas para a sua utilização como resíduo industrial. O extrato foi obtido com aparelho de Soxhlet, utilizando hexano, clorofórmio e metanol como solventes. O extrato hexânico das sementes de Citrus constituiu principalmente por ácido linoleico (36,6%), seguido por ácido α-linoleico (25,3%), ácido oleico (17,8%), ácido palmítico (9,7%) e ácido esteárico (3,3%). As análises indicam que o óleo é semelhante aos utilizados na indústria de cosméticos e de alimentos, tem valor econômico para a utilização na indústria e seu uso provoca alterações no equilíbrio oxidativo, germinação e crescimento...