Stela Maris Kulczynski

COMPARAÇÃO ENTRE MÉTODOS PARA AVALIAÇÃO DA QUALIDADE FISIOLÓGICA E SANITÁRIA DE SEMENTES DE MELÃO 1

RESUMO - O objetivo do trabalho foi avaliar a eficiencia de diferentes testes na identificacao do vigor e da qualidade sanitaria de lotes de sementes de melao (Cucumis melo L.). Foram avaliados quatro lotes de sementes das cultivares Gaucho e Carvalho, produzidas no municipio de HulhaNegra-RS submetidas aos testes de germinacao, primeira contagem de germinacao, emergencia em campo, deterioracao controlada, envelhecimento acelerado, classificacao do vigor de plântulas e sanidade. Os resultados indicaram que os testes de deterioracao controlada e envelhecimento acelerado apresentam sensibilidade suficiente para avaliacao do potencial fisiologico de sementes de melao, mas os testes de avaliacao de plântulas nao mostraram sensibilidade suficiente para realizar uma estratificacao dos lotes pelo vigor. Patogenos como Aspergillus spp. e Fusarium oxysporum interferem na qualidade fisiologica das sementes de melao.

Nitrogênio em cobertura e qualidade fisiológica e sanitária de sementes de painço (Panicum miliaceum L.)

Nitrogen can influence the seed quality of several crops and its effects vary with the environmental conditions and the plant stage when the nitrogen is applied. However, little is known of the influence of nitrogen fertilization on seed quality in proso millet (Panicum miliaceum L.). The objective of this study was to evaluate the effect of dosages and times of nitrogen top-dressing applications on the physiological and sanitary quality of proso millet, cv. AL Tibagi, seeds grown under field conditions. Seeds were produced between December, 2005 and February, 2006 and laboratory evaluations between March and August, 2006. A completely randomized block design in a 4x2 factorial was used, with a combination of four dosages (0, 30, 60, and 120 kg ha-1 of N) and two application times (14 and 28 days after emergence) of nitrogen fertilizer (urea) in top-dressing with four replications. Nitrogen application increased seed vigor, expressed by the tests of accelerated ageing and field emergence. Nitrogen application of proso millet at 28 DAE results in higher IVE and percentage of field emergence. The sanitary quality of Proso millet seed was not influenced by the dosages and times of application of the nitrogen fertilization.

Dessecação pré-colheita e efeitos sobre a produtividade e qualidade fisiológica de sementes de soja

The anticipation of soybean harvest is possible with the use of pre-harvest burn-down practice, which reduces the time of permanence of seeds in the field, after reaching physiological maturation. The objective of this work was to evaluate the effect of time of application of the herbicide paraquat as burn-down during soybean pre harvest on yield and physiological quality of the seeds. The work consisted of two steps: one field experiment, conducted in Jaboticaba-RS, in 2010/2011 and the analysis of the physiological quality of seeds. The treatments consisted of three times of paraquat (240 g a.i. ha-1) application, R6, R7.1 and R7.3, as well as one untreated (without burn‑down). Yield grains and yield components were evaluated. Seed quality analysis was conducted at the Seed Production and Technology Laboratory of UFSM, Campus of Frederico Westphalen, RS, where the following evaluations were carried out : germination, first germination count, root and shoot weight, shoot dry mass of seedlings, accelerated aging, electrical conductivity, field emergence and emergence velocity index. Paraquat application as burn-down practice in soybean pre harvest, at the R6 and R7.1 soybean stages, causes high yield loss in soybean crop. Burn-down without potential yield loss is only viable after R7.3 soybean growth stage. Seeds originated from plants which received paraquat application in R6 and R7.1, show a superior percentile of germination and a higher germination velocity. However, seeds from plants which received paraquat at stage R6 have less seed vigor.

First Report of Meloidogyne ethiopica Parasitizing Sugarcane in Brazil

C. Bellé , Doutorando em Fitossanidade, Universidade Federal de Pelotas, 96010-900, Pelotas, RS, Brazil; S. M. Kulczynski, Universidade Federal de Santa Maria, Frederico Westphalen, 98400-000, RS, Brazil; P. R. Kuhn, EPAGRI, 89893-000, Mondaí, SC, Brazil; R. M. D. G. Carneiro, Embrapa Recursos Genéticos e Biotecnologia, 70770-91, Brasília, DF, Brazil; and I. Lima-Medina and C. B. Gomes, Embrapa Clima Temperado, 96010971, Pelotas, RS, Brazil.

Desempenho fisiológico de sementes olerícolas em diferentes tempos de hidrocondicionamento

The production of high quality physiological seed is a major challenge for seed producers. In the search for lower cost conditioners arises the possibility of using hydropriming, which consists of a controlled hydration of seeds. The aim of this study was to evaluate the efficiency of this technique on lettuce, cabbage and tomato seeds, submitted to different times of imbibition in water. Eight periods of hydropriming in three vegetable crops were used, wherein for each of these was conducted a separate experiment. For lettuce and cabbage, periods tested were 0, 5, 10, 15, 20, 25, 30 and 35 hours and for tomato were of the periods 0, 24, 48, 72, 96, 120, 144 and 168 hours. The seeds of each treatment were submitted to the germination test and vigor to determine the physiological potential. For the tomato crop, the best answers to the average time of germination, emergence speed index and emergency field were found 72 hours of imbibition. As for the cabbage crop the best answers to these variables were obtained with 20 hours of imbibition. Lettuce did not respond positively to the imbibition times.

Physiological potential in rice seeds treated with a plant bioregulator

Os biorreguladores sao compostos naturais ou sinteticos que tem a capacidade de estimular o desenvolvimento radicular e melhorar o desempenho das sementes. O trabalho objetivou avaliar o efeito da utilizacao do biorregulador vegetal Stimulate® no potencial fisiologico de sementes de arroz. O delineamento experimental utilizado foi inteiramente casualizado, em esquema fatorial 4 x 5, sendo quatro cultivares de arroz (IRGA Puita, IRGA 417, IRGA 421, IRGA 424) e cinco doses de Stimulate® (0; 3; 6; 9 e 12 mL kg-1 de sementes), sendo avaliadas as seguintes caracteristicas: teste de germinacao, primeira contagem, plântulas anormais, teste de frio, teste de envelhecimento acelerado, emergencia a campo, indice de velocidade de emergencia, massa seca de plântula, comprimento da raiz primaria e comprimento da parte aerea. A analise de variância identificou efeitos significativos na interacao Cultivar x Dose em todas as variaveis, exceto para o teste de frio e o comprimento da parte aerea. O uso de bioestimulante proporcionou o aumento da germinacao das sementes com potencial fisiologico reduzido e acrescimo no vigor das sementes de todas as cultivares. O potencial fisiologico de sementes de arroz e influenciado pela utilizacao de Stimulate®. As doses de 3 e 6 mL kg-1 de sementes sao as mais recomendadas para a cultura, proporcionando aumentos significativos no seu desempenho fisiologico.

Desempenho de sementes de soja tratadas com bioestimulante sob diferentes condições de potencial osmótico

O trabalho teve como objetivo verificar a influencia do tratamento de sementes com bioestimulante sob condicoes de diferentes potenciais osmoticos e seu efeito sobre o potencial fisiologico da semente e o desenvolvimento inicial da cultura da soja. Os tratamentos foram arranjados em esquema fatorial 2 x 5, sendo, presenca ou ausencia do bioestimulante, e cinco potenciais osmoticos (0,0; -0,3; -0,6; -0,9; -1,2 MPa), com quatro repeticoes. A qualidade fisiologica das sementes foi determinada atraves dos testes de germinacao - primeira contagem da germinacao; classificacao do vigor das plântulas; comprimento e materia seca da parte aerea e das raizes das plântulas. De acordo com os testes realizados, verificou-se que o decrescimo no potencial osmotico, induzido por solucao de NaCl, reduz a germinacao e o vigor de sementes de soja, e que o tratamento de sementes com bioestimulante proporciona aumento no desempenho de plântulas de soja e induz resistencia a condicoes de estresse hidrico.

Atividade antifúngica do extrato natural da acácia-negra à Pycnoporus sanguineus

Among the xylophagous organisms, fungi are mostly responsible for major losses in wood production. The prolonged use of chemical fungicides implies in the emergence of more resistant lines and toxicity in the environment. The goal of this study was to evaluate the toxic effect of the tannin extractive derived from the black wattle (Acacia mearnsii) on the mycelial growth of the fungus Pycnoporus sanguineus, causing white rot. Three methodologies have been developed to work with the product (sterilizing, nonsterilizing and filtering) and four concentrations (0.5, 1.0, 1.5 and 2.0%) were individually incorporated into the culture medium, evaluating the radial growth of the evaluated mycelium and results were compared with the non-treated specimen. The procedure was repeated with the methodology evaluated as being the most adequate, but increasing concentrations (3.0, 4.0 and 5.0%). The concentrations 4 and 5% were more efficient to fungal activity, and the second showed total inhibition in 50% of the plaques evaluated, also showing the smallest mycelial growth rate among all treatments tested.

REAÇÃO DE GENÓTIPOS DE CANA-DE-AÇÚCAR AO PARASITISMO DE Meloidogyne javanica E Pratylenchus zeae

The objective of this work was to evaluate the response of sugarcane genotypes to Meloidogyne javanica and Pratylenchus zeae. Sugarcane seedlings of the genotypes RB985944, RB987932, RB877935, RB855156, RB935744, RB996961, RB925345, RB935581 and RB966928 obtained from tissue cultures and maintained in pots with sterilized soil in a greenhouse were inoculated with 5,000 eggs + secondstage juveniles of M. javanica or 1,600 of P. zeae per plant, using six replicates per treatment. Tomato (Rutgers) and sorghum (BRS506) plants were used as control and proof of viability of the inoculum for the M. javanica and P. zeae, respectively. The number of root-knot in the plants inoculated with M. javanica, final nematode population and reproduction factor (RF) of both nematodes were evaluated at 120 days after inoculation. The averages of the different variables were compared by the Scott-Knotts clustering test at 5%. The nematodes M. javanica and P. zeae showed RF>1.00 in all sugarcane genotypes assessed, however, different levels of susceptibility were found. The lowest reproduction of the nematodes was found in the genotypes RB008347, RB877935, RB975944 and RB987932 (M. javanica) and RB987932 and RB966928 (P. zeae).

Tannic extract potential as natural wood preservative of Acacia mearnsii

High toxicity of the preservatives most frequently used in wood treatment and the resulting risks of handling pose a threat to small producers and to the environment. In an attempt to mitigate these problems, the present study was conducted with the objective of evaluating the preservative effect of tannic extract on biodeterioration of Acacia mearnsii wood. For this purpose, untreated and preserved specimens, some with tannin extract and some with a preservative mixture based on CCB (Chromated Copper Borate), were submitted to accelerated rotting trials with the fungus that causes white rot (Pycnoporus sanguineus) for 16 weeks. The evaluations were made with a basis on weight loss and chemical components analysis, and they showed that the natural resistance of Acacia wood is moderate when exposed to the white rot fungus. The tannin concentrations showed similar effects to those of the CBB mixture in all evaluations, i.e., they significantly increased the biological resistance of the material, which started to be classified as very resistant to the fungus. Overall, the results suggest that tannin can be considered as a potential natural preservative product.