Junior Borella

Waterlogging-induced changes in fermentative metabolism in roots and nodules of soybean genotypes

Waterlogging blocks the oxygen supply to the root system which inhibits respiration, and greatly reduces the energy status of cells that affect important metabolic processes. This study evaluated fermentative metabolism and carbohydrate contents in the root system of two soybean (Glycine max L. Merril) genotypes under hypoxic and post-hypoxic conditions. Nodulated plants (genotypes Fundacep 53 RR and BRS Macota) were grown in vermiculite and transferred to a hydroponic system at the reproductive stage. The root system was submitted to hypoxia by flowing N2 (nitrogen) gas in a solution for 24 and 72 h. For recovery, plants returned to normoxia condition by transfer to vermiculite for 24 and 72 h. Fermentative enzyme activity, levels of anaerobic metabolites and carbohydrate content were all quantified in roots and nodules. The activity of alcohol dehydrogenase, pyruvate decarboxylase and lactate dehydrogenase enzymes, as well as the content of ethanol and lactate, increased with hypoxia in roots and nodules, and subsequently returned to pre-hypoxic levels in the recovery phase in both genotypes. Pyruvate content increased in nodules and decreased in roots. Sugar and sucrose levels increased in roots and decreased in nodules under hypoxia in both genotypes. Fundacep RR 53 was more responsive to the metabolic effects caused by hypoxia and post-hypoxia than BRS Macota, and it is likely that these characteristics contribute positively to improving adaptation to oxygen deficiency.

Atividade alelopática de folhas e pseudofrutos de Hovenia dulcis Thunb. (Rhamnaceae) sobre a germinação de Lactuca sativa L. (Asteraceae)

Neste trabalho, objetivou-se avaliar o efeito alelopatico de folhas secas e pseudofrutos de Hovenia dulcis Thunb. sobre sementes de alface. Para isso, prepararam-se extratos aquosos de folhas e pseudofrutos nas concentracoes 1, 2 e 4% (m/v). Realizou-se quatro repeticoes de 25 sementes de alface, distribuidas em placas de Petri forradas com papel Germitest e umedecidas com os extratos, mantidas em câmara de germinacao a temperatura de 25°C, fotoperiodo constante e presenca de luz por cinco dias, sendo o controle agua destilada. Calculou-se a porcentagem, a velocidade, o indice de velocidade de germinacao, o comprimento radicular e da parte aerea das plântulas, bem como o efeito das sementes na presenca de diferentes solucoes de pH. Observou-se que as plântulas foram significativamente afetadas na presenca de extratos aquosos de folhas secas e pseudofrutos nas concentracoes 2 e 4%. Os efeitos foram desvinculados do pH e potencial osmotico, indicando, portanto, interferencia alelopatica dos extratos obtidos de Hovenia dulcis.

Efeito alelopático de frutos de umbu (Phytolacca dioica L.) sobre a germinação e crescimento inicial de alface e picão-preto

As plantas produzem substâncias por meio do metabolismo secundario. Quando liberadas no meio ambiente sao capazes de interferir na germinacao e no desenvolvimento de outras plantas. Objetivou-se, nesta pesquisa investigar os efeitos alelopaticos de umbu (Phytolacca dioica L.) sobre a germinacao e o crescimento inicial de alface e picao-preto, em laboratorio, utilizando-se extratos aquosos de frutos de umbu nas concentracoes 0, 1, 2, 4 e 8%; foi realizada analise fitoquimica dos frutos e testes de pH e potencial osmotico dos extratos de frutos. Analisaram-se, para a germinacao os parâmetros: porcentagem de germinacao (PG), velocidade de germinacao (VG) e indice de velocidade de germinacao (IVG); para o crescimento inicial analisaram-se os parâmetros: comprimento (radicular e da parte aerea) e biomassa (fresca e seca) das plântulas de alface e picao-preto. Os dados foram submetidos ao teste de Tukey, a 1% de probabilidade. Os parâmetros PG, VG e IVG foram alterados significativamente, proporcionais ao aumento da concentracao dos extratos de frutos do umbu. O comprimento (radicular e da parte aerea) e a biomassa (fresca e seca) das plântulas de alface e picao-preto foram reduzidos significativamente com o aumento da concentracao dos extratos aquosos de frutos de umbu. O pH e potencial osmotico dos extratos mantiveram-se dentro de padroes adequados e a analise fitoquimica revelou a presenca de flavonoides. Pelos resultados os frutos de umbu apresentaram-se com efeito alelopatico sobre a alface e o picao-preto.

Respostas na germinação e no crescimento inicial de rabanete sob ação de extrato aquoso de Piper mikanianum (Kunth) Steudel

This study evaluated the allelopathic effects of an extract from P. mikanianum leaves on the germination and early growth of radish (Raphanus sativus L.). Leaf extracts were prepared at concentrations of 2, 4 and 8%. The pH and osmotic potential of the extracts were determined. Germination bioassay consisted of five replicates of 25 radish seeds distributed in Petri dishes with germitest paper and 7 mL of extract or water, and were kept at 25oC in B.O.D. for five days. Germination percentage (PG), germination speed (VG), germination speed index (IVG) and index of allelopathic effect (RI) were determined. For bioassay initial growth, seeds were germinated until the protrusion of the radicle was 2 mm and transferred to Gerbox boxes containing germitest paper and 15 mL of extract or water, which were kept for seven days at 25oC in B.O.D. to evaluate the length of the radicle and hypocotyl, fresh and dry mass, water content and chlorophyll content (a, b ​​and total). Leaf extracts from P. mikanianum negatively affected all parameters examined for germination (PG, VG, IVG and RI). The extracts affected the initial growth, causing reduction of the radicle length and stimulating the growth of the hypocotyl. In addition, the extracts at 8% concentration reduced fresh weight and water content. Extracts at concentrations of 2 and 4% increased the content of chlorophyll b and total chlorophyll. Thus, Piper mikanianum exerted an allelopathic effect on radish.

Seed vigor, antioxidant metabolism and initial growth characteristics of red rice seedlings under different light intensities

This work aimed to evaluate the effect that different intensities of light have on the physiological attributes of red rice seeds and seedlings. Before and after emergence, seedlings were exposed to light levels of 35%; 65% and 100% in a greenhouse. We evaluated shoots and roots, in terms of length and dry mass, as well as leaf area and content of chlorophyll (a,b and total). In leaves and roots, we quantified the activity of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and guaiacol peroxidase (POX). We determined the leaf area ratio (FA), leaf mass ratio (FW), specific leaf area (SA), and shoot/root ratio (PW). At higher light intensities, shoot length decreased, whereas root length, dry mass and number of tillers increased. Leaf area was greatest in seedlings exposed to a 65% light level. The FA, FW, SA and PW were lowest at a light intensity of 100%. Differences in light intensity had qualitative and quantitative effects on chlorophyll contents. The activity of SOD and CAT was higher at lower light levels, whereas the inverse was true for APX and POX activity. Extremes of light availability alter the activity of antioxidant enzymes, negatively affecting the initial growth characteristics and photosynthetic pigments of red rice seedlings.

Atividade de enzimas fermentativas em raízes e nódulos de soja sob condições de hipóxia e pós-hipóxia

This study aimed to evaluate the activity of fermentative enzymes in soybean (Glycine max) roots and nodules under hypoxia and post-hypoxia conditions. The soybean genotypes Fundacep 53 RR and BRS Macota associated with Bradyrhizobium elkanii were grown in 3L pots containing vermiculite as substrate under greenhouse conditions. Root system of plants at the R2 stage was subjected to hypoxia by blocking drainage of the pot, by fitting a second one without holes and flooded with nutrient solution diluted one-third of the original. The flooding of the plants was carried out for eight days and after, the pot without drilling was removed for recovery assessment. Non-waterlogged plants were kept as control. Activities of the fermentation enzymes alcohol dehydrogenase (ADH), pyruvate decarboxylase (PDC) and lactate dehydrogenase (LDH) were quantified in roots and nodules collected at 2, 4, 6 and 8 days after flooding or recovery. Data were analyzed by ANOVA and compared by the Tukey test (P ≤ 0,05). Activities of ADH, PDC and LDH were hardly stimulated during flooding, especially in nodules, in both genotypes and decreased with recovery. Fundacep 53 RR responded more effectively to treatment effects.

Isoenzymatic expression of red rice seeds and seedlings under the action of extracts of two Araceae species.

Several plant extracts have phytotoxic potential on seeds and seedlings, while the evaluation of isoenzymes is an important tool in assessing seed quality. In this study, we aimed to evaluate the effect of extracts the two species of the Araceae family (Zantedeschia aethiopica, Philodendron bipinnatifidum) on the isoenzymatic expression of red rice seeds and seedlings. We used the following extract concentrations: 0; 12; 25; 50 and 75%. Evaluation stages were seed, first count, and germination test. Expression of the isoenzymes esterase, acid phosphatase, glutamate oxaloacetate transaminase and peroxidase was determined by the vertical electrophoresis system in polyacrylamide gel, and interpretation of results was made by visual analysis of the gels. The extracts of the Araceae family species altered the isoenzymatic expression, and the intensity and number of bands varied according to the concentration and the stage of evaluation. Expressão isoenzimática de sementes e plântulas de arroz-vermelho sob ação do extrato de duas espécies Araceae Isoenzymatic expression of red rice seeds and seedlings under the action of extracts of two Araceae species Tiago Zanatta Aumonde1* Tiago Pedó1 Emanuela Garbin Martinazzo2 Junior Borella2 Francisco Amaral Villela1 1Universidade Federal de Pelotas – UFPel, Faculdade de Agronomia Eliseu Maciel, Departamento de Fitotecnia, Campus Capão do Leão, CP 354, 96010-900, Pelotas, RS, Brasil 2Universidade Federal de Pelotas – UFPel, Instituto de Biologia, Departamento de Botânica, Campus Capão do Leão, CP 354, 96010-900, Capão do Leão, RS, Brasil Autor Correspondente: *E-mail: tiago.aumonde@gmail.com PALAVRAS-CHAVE Oryza sativa Zantedeschia aethiopica Philodendron bipinnatifidum Alelopatia