José Roberto Pinto de Souza

Antifungal activity of essential oil isolated from Ocimum gratissimum L. (eugenol chemotype) against phytopathogenic fungi

An investigation of antifungal activity of the essential oil obtained by steam-distillation (1.1% w/w) of the aerial parts of Ocimum gratissimum and of an ethanolic extract from the steam-distillation residue was carried out using the agar diffusion method. The results revealed that the essential oil inhibited the growth of all fungi tested, including the phytopathogens, Botryosphaeria rhodina, Rhizoctonia sp. and two strains of Alternaria sp., while the extract from the residue was inactive. The essential oil was subjected to TLC bioautography used to detect fungitoxic constituents. The compound that showed antifungal activity was isolated and identified as eugenol. GC/MS analysis showed that eugenol was the main constituent of the essential oil studied. The antifungal activity of eugenol was evaluated against a species of Alternaria isolated from tomato (A1) and Penicillium chrysogenum. The minimal inhibitory concentrations of eugenol were 0.16 and 0.31 mg/disc for Alternaria sp. (A1) and P. chrysogenum, respectively.

Estimativa da área foliar do feijão-vagem (Phaseolus vulgaris L.) por meio da largura máxima do folíolo central

An experiment was conducted to establish a mathematical model based on the linear measurement of the maximum width of the central leaflet to estimate the leaf area of determinate type of snap bean. The measurements were made using the non-destructive method in six plants and the destructive method in four plants on the 21, 30, 37, 44 and 51 days after emergence. The area of each leaflet was obtained by using an area meter LICOR LI-3000 model. The models, obtained by regression, were tested in destructive and non-destructive methods comparing the estimated and the measured leaf area. The model AF = 0.1026*L1,6871 (R2=0.98) was effective to estimate the leaf area (AF) of snap bean plants in non-destructive way showing that the maximum width of the central leaflet (L) estimates the real leaf area.

Path analysis under multicollinearity in soybean

This study aimed to establish the phenotypic correlations among several soybean traits with grain yield in direct and indirect effects using path analysis, and to compare alternative methods for minimizing the adverse effects of multicollinearity in estimating path coefficients. The experiment was conducted in greenhouse in a randomized complete block design with four replications. Nine soybean genotypes belonging to three seed size categories were used. The correlation studies and the path analysis showed that the seed size was not important for increased yield. The number of nodes and plant height at maturity showed significant correlation with grain yield. Using the least square methodology, the results obtained by path analysis under multicollinearity were not satisfactory. The ridge path analysis and the trait culling were efficient in reducing the adverse effects of multicollinearity. Both methods showed that only the number of nodes at maturity trait had a high direct effect on grain yield per plant.

Potenciação alelopática de extratos vegetais na germinação e no crescimento inicial de picão-preto e alface

O picao-preto (Bidens pilosa L.) e uma planta daninha muito agressiva, que esta presente em quase todo Brasil. O principal metodo de controle e o quimico, porem apresenta elevado impacto ambiental, risco de intoxicacao humana e possibilidade de causar fitotoxicidade as culturas. O objetivo do trabalho foi avaliar o efeito alelopatico de extratos etanolicos de Eucalyptus citriodora Hook. e Pinus elliottii L. na germinacao e no crescimento inicial de picao-preto e alface (Lactuca sativa L.). Foram testadas quatro concentracoes de cada extrato (0,25; 0,50; 1,0 e 2,0 %) alem do controle (0,0 %) agua destilada com Tween 20 a 0,08 %. O delineamento experimental foi o inteiramente casualizado, com quatro repeticoes em condicoes de laboratorio. O extrato de P. elliottii nao causou efeito alelopatico sobre o picao-preto e o alface. O extrato de E. citriodora reduziu significativamente o indice de velocidade de germinacao (IVG) do picao-preto em todas as concentracoes testadas quando comparadas com o controle (0,0%), porem para a alface o IVG foi significativo apenas na concentracao de 2,0 %. Para o comprimento da raiz nao foi possivel observar diferenca significativa entre os tratamentos para os dois extratos testados tanto para o alface como para o picao preto.

Qualidade de mudas de guaco produzidas por estaquia em casca de arroz carbonizada com vermicomposto

O guaco e uma especie medicinal cuja parte da planta utilizada sao as folhas. A propagacao das plantas da-se por meio de estacas. O objetivo deste trabalho foi avaliar ao longo do tempo o desenvolvimento e a qualidade de mudas de guaco propagadas por estacas em diferentes concentracoes de vermicomposto adicionado a casca de arroz carbonizada. O delineamento experimental foi de blocos casualizados com parcelas subdivididas [cinco proporcoes de vermicomposto (0; 5; 10; 20 e 40%) e cinco epocas de avaliacao (60; 70; 80; 90 e 100 dias)], com quatro repeticoes. Cada parcela foi composta por 60 estacas (15% de ramos apicais, 70% de ramos medios e 15% ramos basais). Foram avaliados a altura, diâmetro; retencao foliar; numero e comprimento de brotos; area foliar; peso seco das folhas, caule, parte aerea, sistema radicular e total; relacao parte aerea/sistema radicular; altura/diâmetro da base da estaca; altura/peso seco da parte aerea e o Indice de Qualidade de Dickson (IQD). Todas as estacas de guaco avaliadas formaram sistemas radiculares com a adicao ou nao de vermicomposto a casca de arroz carbonizada. As mudas de guaco alcancaram boa qualidade entre 90 a 100 dias apos o transplantio das estacas. Os parâmetros que definiram a qualidade das mudas foram o peso seco da parte aerea por peso seco do sistema radicular, altura da parte aerea por peso seco da parte aerea, altura da parte aerea por diâmetro da base da estaca e IQD, que apresentaram os valores de 5,85; 4,24; 14,41 e 0,17, respectivamente.

Tempo de armazenamento e temperatura na porcentagem e velocidade de germinação das sementes de camomila

Chamomile is an annual herbaceous species. Its flowers are used in popular medicine and as a vegetable flavour. It propagates for seeds. The objective of these trials was to evaluate the ideal temperature, packing time on the percentage and germination speed of chamomile. The first trial used seeds from a medicinal vegetable garden from Universidade Estadual de Londrina, Parana, Brazil. They were treated, packed in paper bags and kept in refrigerate chamber during one, two, three and four years. In germination test it was used 25°C with 10 hours of light and 14 hours of dark. It was evaluated the percentage and germination speed index (GSI) in 8 replicates with 100 seeds each one. The seeds used in the second trial were commercial ones. The tested treatments were: constant temperatures of 10°C and 15°C with 12 hours of photoperiod, and alternated temperatures of 10°C/15°C and 10°C/20°C with 10 hours of photoperiod. The evaluations were made at 7th and 14th days after seeding. The seeds packed until 2 years showed greatest percentage and germination speed index. The temperature of 10°C reduced the germination for 3.3% at 7 DAS. The constant temperature of 10°C and 15°C, and alternated in 10°C/15°C and 10°C/20°C provided germination of the seeds superior to 80% in the end of 14th day.

Crescimento de mudas de peroba rosa em resposta à inoculação com fungos micorrízicos arbusculares

The aim of this study was to examine the effects of arbuscular mycorrhizal fungi (AMF) inoculation on Aspidosperma polyneuron seedlings growth. The experiment was conducted under greenhouse conditions in a randomized design using a disinfected mixture of soil + sand (3:1) with the following treatments: Gigaspora margarita, Glomus clarum, Scutellospora heterogama, Acaulospora scrobiculata, a mixture of arbuscular mycorrhizae fungi (AMF) and a non-inoculated control with six replicates. After 120 days of seed germination, it was observed that root colonization was from 28.3% to 48.4% for mixture of AMF and G. margarita, respectively. The plants inoculated with G. margarita or G. clarum showed higher growth than other treatments, which evidence the potential of AMF inoculation in seedlings production.

Teor de cálcio em frutos de diferentes cultivares de feijão-vagem

The calcium concentration in the pods of several snap beans was studied in two experiments carried out in 1997 and 1998 in Londrina, Parana state, Brazil. A randomized complete block design with four replications was used. Pods classified as number four (8.3 to 9.4 mm diameter) were assessed. The calcium concentrations in the cultivars Xera, Paulista, Florence, 274, F-15, Nerina, Anseme and UEL-1 were compared by the Duncan test at P < 0.05. In the two years analyzed, the Xera cultivar presented the greatest calcium concentration with an average of 6.1 mg calcium/g dry matter, while the Nerina cultivar showed the lowest concentrations with 4.5 mg calcium/g dry matter. It was concluded that calcium accumulation in the pod was influenced by the genotype of the cultivar regardless of the agricultural year studied.

Ação do imazapic+imazapyr sobre a tiririca (Cyperus rotundus) e os desnitrificadores em milho

The objective of this work was to evaluate the efficacy of imazapic+imazapyr in controling purple nutsedge and its effect on the population of denitrifying bacteria in soil cultivated with corn. The trial was set up in 0.70 x 0.30 x 0.30 m boxes where imidazolinone tolerant corn (C901CL) was seeded together with 50 purple nutsedge bulbs. The experimental design was randomized with six replications. The treatments were: 1) corn without nutsedge; 2) corn with nutsedge; 3) corn with cut nutsedge; 4) corn with nutsedge treated with imazapic+imazapyr (63+21 g ha-1 i.a) applied in post-emergence and 5) corn with nutsedge treated with imazapic+imazapyr (63+21 g ha-1 i.a), applied in pre-emergence. The herbicide was efficient when applied in post-emergence, reducing in 41% the setting of aerial parts of the nutsedge with visual control effect of 88%, twenty-one days after spraying. The soil denitrifying bacteria increased six and ten-fold, 24 and 54 days after corn seeding, respectively, in the presence of purple nutsedge. The application in post-emergence reduced the denitrifying population to 1.91x105 MPN (most probable number) , 89% less than the non-weeded check (16.78x105 MPN).

Genetic variability of three natural populations of Maytenus aquifolium (Celesteraceae) from Telêmaco Borba, Paraná, Brazil

Three populations of Maytenus aquifolium from Monte Alegre farm, Telemaco Borba county, Parana, Brazil were analyzed by RAPD markers. A total of 13 primers were applied wich yielded 283 well amplified markers in all the studied populations (Mortandade, Vila Preta and Trinita), producing different values of gene diversity and polymorphic loci. The analysis of molecular variance (AMOVA) indicated that 21.77% of the genetic variation was among the population. Pairwise FST analysis showed that the most divergent populations were closer geographically, demonstrating that other factors such as different soil types could explain this variation. Bayesian analysis for K number of clusters and the Principal Coordinate indicated that these three populations were highly structured, corroborating the high values found for the FST and indicating that for conservation purposes all populations should be maintained.