Superação da dormência em sementes de Brachiaria humidicola cv. BRS Tupi durante o armazenamento

Pós-graduação em Agronomia (Agricultura) - FCA

Qualidade de sementes de soja convencional e transgênica em função da dessecação das plantas com glyphosate

Pós-graduação em Agronomia (Agricultura) - FCA

Phytotoxicity of ethanolic extract of turnip leaves (raphanus sativus l.)

The study of allelopathic activity has been aim of research that evaluates mainly species used in green fertilization. Raphanus sativus L. stands out among these species, because it shows high capacity for nutrient recycling, specially nitrogen and phosphorus, what makes it an advantageous cover plant in crop rotation systems. Considering the exposed, the present study had as objective the evaluation of the allelopathic and phytotoxic potentials of different concentrations of the R. sativus leaves ethanolic extract by mean of seeds germination analyses and development of lettuce seedlings, evaluating the phytotoxicity by determination of the mitotic index of lettuce root cells, realizing the phytochemical profile and investigating the antioxidant activity. It was possible to verify that the R. sativus extract interferes in the germination index, decreasing the germinability (5 mg. mL(-1) = 9.84%; 10 mg. mL(-1) = 11.91% and 20 mg. mL(-1)= 57.51%). In the lettuce seedlings growth, the extract of this species affected the roots and hypocotyls growth. It was possible to observe phenols and total flavonoids in the extract for the concentration of 1000 mu g. mL(-1)(161mg and 83.57 mg, respectively). It was also observed, higher antioxidant activity for the concentration of 1000 mu g. mL(-1) (89.76%). In the phytotoxicity assay was observed a dose dependent effect in the mitotic index and in the cellular events during cellular division. In this study it was possible to conclude that this species has allelochemical compounds which are able to interfere directly on the stabilization and development of other species.

Efeito de maturadores sobre a germinação e crescimento inicial de corda-de-viola

Pós-graduação em Agronomia (Produção Vegetal) - FCAV

A novel synthesis of perovskite bismuth ferrite nanoparticles

Abstract. Biochar is the solid by-product of biomass pyrolysis. It is a promising soil conditioner and can be a material with high aggregate economic value, since its performance can improve plant’s nutrient utilization and reduce the usage of conventional fertilizers. Biochar can be used in the formulation of new types of fertilizers as polymeric microbeads. These microbeads can be enriched with biochar and nutrients in its matrix to form fertilizers of slow release of nutrients. Thus, as a promising agricultural material, it is important to assess the environmental hazards caused by the implementation of these microbeads. In this context, seeds were sown in a soil-less Petri dish with microbeads produced with biochar from sugarcane enriched with or without phosphate. The seeds germination and its vitality were evaluated by the first germination count (FGC) and the germination speed index (GSI). The short-term effects showed that the microbeads, in general, assessed by the means of FGC, GSI and mass gain showed the best performance, suggesting that the environment created by these materials provided the best chemical and physical interaction with the embryonic axes.

Qualidade fisiológica de sementes de Senna multijuga de diferentes procedências do estado de São Paulo

Pós-graduação em Agronomia (Produção Vegetal) - FCAV

Phytotoxicity of Solanum aculeatissimum Jacq: leaves extract

The objective of this study was to evaluate the phytotoxicity of Solanum aculeatissimum Jacq. leaves ethanolic extract in seeds germination, development and fixation of Lactuca sativa seedlings. The same study also aimed to assess the mitotic index of lettuce roots meristematic cells, quantification of phenols and total flavonoids and triage by mean of phytochemical testing of the main secondary metabolites classes. Bioassays of germination, development of root and hypocotyl were carried out in Petri dishes using achenes of Lactuca sativa L. cv. 'Grand Rapids' (lettuce). Concomitantly, were evaluated the physico-chemical characteristics (pH, osmotic potential and electrical conductivity), mitotic index, quantification of total phenols and flavonoids and determination of phytochemical profile of the treatments extract. The results obtained in the bioassays demonstrate that the ethanol extract of S. aculeatissimuma presents phytotoxic potential in the development of lettuce seedlings, given that the concentration of 20 mg/ml showed greater inhibition (41% of germination). The extract contains significant amounts of antioxidants, total flavonoid and phenols, where the concentration 1000µg/mL showed higher values (86.50%). Furthermore, it was possible to observe the presence of compounds with allelopathic activity in the phytochemical screening test as coumarins, tannins, terpenes, flavonoids and alkaloids. Given the above it is clear that the ethanolic extract of S. aculeatissimum presents allelopathic substances with phytotoxic activity that can affect the germination and development of other plant species in their natural environment.

Subdoses de glyphosate no desenvolvimento de espécies arbóreas nativas

Recovery of degraded areas aims to provide the degraded environment favorable conditions for restructuring in an environment that is unable to regenerate itself and planting of tree seedlings is one of the effective ways to extend this process. However, native tree species have slow growth rate which increases the seedlings production time as well as decreases their competitiveness with weeds in areas of forests deployment. The aim of this study was to evaluate the effects of glyphosate reduced rates application on Psidium cattleyanum (yellow guava), Citharexylum myrianthum (pau-viola) and Cedrela odorata (cedro) seedlings development by analyzing its morphophysiological parameters. The experiment was carried out in greenhouse conditions and the experimental units consisted of one plant were conducted in 2.5L plastic pots and arranged in a completely randomized design with six replications. Treatments consisted of glyphosate application at 0, 7.5, 15, 30 and 60 g ha(-1) using Scout (R) commercial formulation. Treatments application on these species seedlings was realized 120 days after seeds germination. Visual evaluations of plants phytotoxicity were realized at 7, 14 and 21 days after treatments application and plants survival, stomatal conductance, height, stem diameter and dry mass of shoots were evaluated 90 days after treatments application. Different doses of glyphosate did not cause plants phytotoxicity. Already, 30 and 60 g ha(-1) of glyphosate provided greater increases in height, stem diameter and dry mass of shoots for Citharexylum myrianthum and Psidium cattleyanum, respectively.

Extratos vegetais na germinação de sementes de Baccharis dracunculifolia e Plantago lanceolata

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Qualidade da operação de semeadura de uma semeadora adubadora de plantio direto em função do tipo de martelete e velocidade de deslocamento

The current paper had as its objective to analyze the precision planter's operational performance according to five different displacement velocities and two types of jumpers for planting no-tillage corn. The utilized experimental delineation consisted of blocks at random with parcels subdivided in factorial scheme 2x5, two types of jumpers (4 and 5 staples) and five different displacement velocities (3.0; 4.5; 5.0; 7.0 e 9.0 km h-1) with four repetitions and by applying the average comparation test, as for the jumpers effects as for the displacement velocities effects, to the significance level of 5%. It was evaluated the data concerned to the longitudinal distribution of plants, average number of days for the emergence of seedlings, initial and final stand of plants, survival indices, mechanical harm on seeds, germination tests and grain production. It was also observed the planter displacement velocity effect of on variables as: longitudinal distribution of plants, average number of days for the emergence of seedlings, initial and final stand of plants, mechanical harm and yield. The survival indice of plants were high for all the studied velocities and jumpers. Among the studied velocities, the one of 5.0 km h-1 presented the highest yield to both types of jumpers.

Observaciones sobre la biología de tres cactáceas argentinas

En vista de que faltan las observaciones biológicas sobre muchas de las Cactáceas argentinas, el autor ha creído útil hacer conocer las que ha realizado sobre tres de ellas pertenecientes a los géneros Echinopsis, Pterocactus y Maihuenia, verificadas en el hábitat de las mismas o sobre materiales mantenidos en cultivo durante más de dos décadas. Documenta, en Echinopsis mirabilis, su ántesis nocturna, en Pterocactus cfr. tuberosus, la vitalidad de sus tubéculos radicales, en Maihuenia cfr. Valentinii, la estructura morfológica de la semilla, y en las tres especies, la estructura morfológica de sus pólenes y la germinación de sus semillas. La irritabilidad estaminal y el modo de diseminación de algunas de estas Cactáceas y su tipo biológico, han sido tomados también en consideración. Se mencionan los materiales de herbario revisados (dispersión local), los de plantas vivas que observó y las instituciones donde se ha depositado la documentación palinológica.

Extratos de Ascophyllum nodosum no tratamento de sementes de milho e soja: avaliações fisiológicas e moleculares

A obtenção de uma lavoura com população adequada de plantas depende da utilização de diferentes práticas agronômicas, estando o sucesso condicionado ao uso de sementes de boa qualidade. No entanto, a semeadura dificilmente é realizada em condições ideais o que resulta em problemas na emergência das plantas. Grande é a procura por alternativas que melhorem a germinação e o desenvolvimento inicial dos cultivos resultando em uniformidade de emergência, garantindo o estande e culminando em produção. O tratamento de sementes com agroquímicos fitossanitários é uma solução parcial no combate de agentes fitopatológicos e pragas, mas poucas são as soluções adotadas para melhorar o desenvolvimento vegetal inicial, que pode levar a desuniformidade e falhas no estande gerando prejuízos econômicos. Os extratos de algas já demonstraram em diversos estudos sua eficiência no desenvolvimento vegetal quando aplicados em plantas. Porém poucos são os estudos voltados para os efeitos dos extratos de algas na germinação e emergência. Assim, o intuito deste trabalho foi testar o extrato comercial de Ascophyllum nodosum, e diferentes fracionamentos do mesmo, no tratamento de sementes de soja e milho. Avaliou-se o efeito de diferentes doses no desenvolvimento das plântulas e as doses de melhor resposta foram utilizadas no tratamento de sementes de soja a fim de associar as respostas obtidas à expressão gênica de 9 genes relacionados ao processo germinativo em 24 e 48h de embebição. Sementes de soja tratadas com o extrato comercial resultaram em plântulas menos desenvolvidas o que pode estar relacionado ao alto teor de sais contidos no produto. O tratamento com as demais frações favoreceu o desenvolvimento das plântulas, principalmente o desenvolvimento radicular. Sementes de milho tratadas não apresentaram desenvolvimento tão satisfatório quanto as sementes de soja tratadas. A análise da expressão gênica relativa demonstrou que o tratamento com frações do extrato comercial é capaz de regular algumas vias do metabolismo hormonal, como a isopentenil transferase e a GA20 oxidase 2, e do catabolismo de reservas, como a acil-CoA oxidase. Em condições ótimas, o tratamento de sementes de soja com frações do extrato comercial de A. nodosum favoreceu o desenvolvimento inicial das plântulas de soja, no entanto não ocasionou grandes alterações no desenvolvimento de milho. Este estudo demonstrou a possibilidade de utilização de frações do extrato de A. nodosum no favorecimento do desenvolvimento inicial de plântulas de soja. Maiores estudos são necessários quanto às respostas em campo e na atenuação de estresses para viabilizar seu uso como um bioestimulante em sementes.

Fruit processing, seed viability and dormancy mechanisms of Persoonia sericea A. Cunn. ex R. Br. and P-virgata R. Br. (Proteaceae)

The morphology of the fruit and difficulties with fruit processing impose major limitations to germination of Persoonia sericea and P. virgata. The mesocarp must be removed without harming the embryo. Fermentation of fruit or manual removal of the mesocarp was effective but digestion in 32% hydrochloric acid (HCl) completely inhibited germination. The endocarp is extremely hard and therefore very difficult and time consuming to remove without damaging the seeds. The most efficient method was cracking the endocarp with pliers, followed by manual removal of seeds. Germination was completely inhibited unless at least half of the endocarp was removed. Microbial contamination of the fruit and seeds was controlled by disinfestation and germination of the seed under aseptic conditions. The results suggest that dormancy in these species is primarily due to physical restriction of the embryo by the hard endocarp.

Efeito de fatores ambientais e tolerância a herbicidas em três espécies de plantas daninhas da família Rubiaceae

The strong selection pressure exerted by intensive use of glyphosate in cultivated areas has selected populations of the Rubiaceae weed species Borreria latifolia (Aubl.) K.Shum. (broadleaf buttonweed), Galianthe chodatiana (Standl.) E.L. Cabral (galiante) and Richardia brasiliensis Gomes (Brazilian pusley) with differential sensitivity to this herbicide in the South region of Brazil. The control of these weeds with herbicides is troublesome and signals the need to incorporate management practices of ruderal flora and crops, more sustainable and that results in more efficient control for long-term. Therefore, it is very important to expand the information about their biology and management. This study aimed: (a) select efficient methods to overcome dormancy of B. latifolia and G. chodatiana and determine how they influence the kinetics of seeds germination; (b) analyze the effects of temperature, irradiance, pH, aluminum and salinity on seed germination and initial growth of the B. latifolia, G. chodatiana e R. brasiliensis seedlings; (c) evaluate tolerance to glyphosate levels in biotypes of B. latifolia, G. chodatiana e R. brasiliensis through dose-response curves and compare two methods to evaluate herbicidal control; (d) and evaluated the effectiveness of alternative herbicides in pre-emergence and in early and late post-emergence of the three species. The treatment with KNO3 2%/3h + gibberellic acid 400 ppm resulted in higher percentage of G. chodatiana seed germination. This treatment and also the dry heat (60°C/30 min) + KNO3 2%/3h were more effective in overcoming dormancy of B. latifolia. G. chodatiana and R. brasiliensis tolerate lower temperatures during the germination process, while B. latifolia tolerate higher temperatures. B. latifolia and R. brasiliensis are positive photoblastic while G. chodatiana is indifferent to the photoperiod. B. latifolia shows higher germination and early development in pH 3, while G. chodatiana and R. brasiliensis prefer pH range between 5 and 7. B. latifolia and G. chodatiana were more tolerant to the aluminum during the germination process than R. brasiliensis. Low salt levels were sufficient to reduce the seed germination of the three species. Some biotypes of B. latifolia and R. brasiliensis showed medium-high glyphosate tolerance, not being controlled by higher doses than recommended. The G. chodatiana specie was not controlled with the highest dose used, showing a high glyphosate tolerance. The sulfentrazone, s-metolachlor and saflufenacil herbicides sprayed in pre-emergence showed high efficacy both on B. latifolia and R. brasiliensis, while chlorimuron-ethyl and diclosulan were effective only on R. brasiliensis. In early post-emergence the fomesafen, lactofem and flumioxazin herbicides efficiently controlled plants of all species, while bentazon showed high efficacy only on B. latifolia. Noteworthy the susceptibility of the G. chodatiana specie for applications in early post-emergence, because the control effectiveness and the number of effective herbicides are reduced with increasing the plant age. Many treatments with tank mix or sequencial applications with glyphosate, were effective in controlling B. latifolia and R. brasiliensis plants in advanced stage of development.

Germinação e armazenamento de sementes de COCA (Erythroxylum ligustrinum DC. - Erythroxylaceae)

O objetivo deste trabalho foi avaliar o efeito da temperatura sobre a germinação e o armazenamento de sementes de Erythroxylum ligustrinum DC. As sementes foram colocadas germinar caixas de plásticas sobre duas folhas de papel, umedecidas com Nistatina 0, 2%, mantidas em germinadores nas temperaturas constantes de 5, 10, 15, 20, 25, 30, 35, 40 e 45ºC e com fotoperíodo de 12 horas. Para o armazenamento, as sementes foram colocadas em sacos de papel, mantidos à temperatura ambiente e em geladeira. em seguida, mensalmente, foi avaliada a germinação das sementes. A temperatura mínima, a faixa de temperatura ideal e a temperatura máxima para germinação de sementes de coca estão entre 10 e 15ºC, 25 e 30ºC e 40 e 45ºC, respectivamente. O armazenamento de sementes coca por longo período é inviável em embalagens de papel na geladeira (10ºC ± 2) e em temperatura ambiente (27ºC ± 5).