Reaction and colonization of common bean genotypes by INTRODUCTIONBrazil is one of the world's leading common bean producers and consumers, with a harvest of almost three million tons in 2012, in the main producing states of Paraná, Minas Gerais, São Paulo and Goiás (Agrianual 2013). Bacterial diseases are among the yield-limiting factors of the crop in the country, particularly bacterial wilt. This disease is caused by Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff), and was first described by Hedges (1922) in the USA. Currently, the disease has already been detected in several countries (EPPO 2011) and Brazilian states (Valentini et al. 2010). Bacterial wilt colonizes the xylem vessels of the affected plants, leading to disruption and degradation of the primary xylem. Infected plants show symptoms of wilting leaves, which later evolve to withering and death (Dinesen 1978). Yield losses in susceptible cultivars can be close to 50% (Miranda Filho 2006). Bacterial wilt is controlled by preventive measures, e.g., by using healthy seeds, incorporation of crop bean residues into the soil, crop rotation with non-host species, and by using cultivars with some level of resistance (Huang et al. 2009, Valentini et al. 2010.A number of studies identified Cff-resistant common bean genotypes in Brazil. According to Maringoni (2002), high resistance levels were observed in the cultivars IAC Carioca Akytã, IAC Carioca Aruã, and IAC Carioca Pyatã. Souza et al. (2006) Carioca Aruã, IAC Carioca Pyatã, and IAC Carioca Tybatã, whose resistance reactions were found to be as described by Maringoni (2002) and Souza et al. (2006).
Agronomic performance, heterosis and phenotypic stability of onion genotypesThe objective of this study was to evaluate the performance, heterosis and phenotypic stability of 50 genotypes of onion (a lineage and eight experimental hybrids of Baia group, 10 lineages and 22 experimental hybrids of Creole group, six open pollinated varieties and three commercial hybrids) in three crop seasons in Guarapuava, Paraná state, Brazil, in 2010/2011. Three experiments were carried out in randomized block design with three replications. Seedlings aging 45 days were transplanted on May 27, June 30 and August 03. We evaluated agronomic characteristics of bulbs. For the analysis of phenotypic stability of genotypes the method of Annicchiarico was used. We also estimated the heterosis of seven hybrids. The first period provided the highest values of average mass and increased yield of bulbs and the third period provided the lowest values. Only 26% of genotypes showed general confidence index (w i ) above 100% for bulb yield. The experimental hybrids HB1266, HB2285, HC3119, HC3126, HC3479 and HC3488 showed the highest confidence index for bulbs yield, although in the first period they did not participate in the group of highest yield genotypes. The mean of heterosis observed for the average mass of bulbs was 38%, ranging from 16% (HC3485) to 63% (hybrid HC3483) and for yield was 36%, ranging from 16% (HC3485) to 57% (HC3483).
We study a particular class of Lotka-Volterra 3-dimensional systems called May-Leonard systems, which depend on two real parameters a and b, when a + b = −1. For these values of the parameters we shall describe its global dynamics in the compactification of the positive octant of R 3 including its infinity. This can be done because this differential system possesses a Darboux invariant.
A medida mais utilizada para o controle de oídio em cucurbitáceas é o uso de variedades resistentes e fungicidas sistêmicos, entretanto, a nutrição silicatada tem se mostrado uma opção. O fornecimento do silício é benéfico para muitas espécies vegetais, estimulando o crescimento, a produção, a fotossíntese e a regulação da transpiração; além disso, sua deposição na epiderme evita a invasão de fungos, bactérias e insetos sugadores. O objetivo deste trabalho foi verificar a influência do silicato de potássio no controle do oídio, e no desenvolvimento e na produção de abobrinha de moita, cultivar Caserta. O experimento foi conduzido em cultivo protegido, com delineamento inteiramente casualizado, quatro repetições e cinco tratamentos: testemunha (água); tratamento químico com fenarimol (2,4 g i.a 100 L-1) e silicato de potássio, nas doses de 1,5 L ha-1; 2,0 L ha-1 e 2,5 L ha-1. Foram avaliados a severidade da doença; trocas gasosas; crescimento e produção de frutos. Os resultados mostraram que a aplicação foliar de silicato de potássio com fenarimol controlou o oídio e não teve influência no crescimento da planta. Portanto, o silicato de potássio pode ser utilizado como alternativa para o controle desse fungo e diminuição da aplicação de produtos químicos, o que proporciona uma maior sustentabilidade ambiental. No entanto, deve-se tomar cuidado com dosagens altas, pois observou-se que a dosagem de 2,5 L ha-1 foi prejudicial à produção de frutos e às trocas gasosas, apesar de ter sido eficiente no controle do oídio. Recomenda-se o uso de 2,0 L ha-1 de silicato de potássio para o controle de oídio para abobrinha de moita, podendo substituir o uso de fenarimol, sem afetar a produção e desenvolvimento das plantas.
In order to produce bulbs or seeds, onion plants depend on genotype X environment interaction. Thus, breeders shall select the genotypes based on the climatic conditions of each producing region. This study aimed to evaluate 17 experimental onion hybrids and two commercial genotypes (‘Bella Dura’ and ‘Buccaneer’), based on agronomic, physicochemical attributes of the bulbs and resistance to early flowering under subtropical conditions. Joint analysis of variance and phenotypic divergence estimated through principal component analysis (PCA) and Ward’s hierarchical clustering were performed. We observed that the time of transplantation affected the agronomic traits more than the physicochemical traits, not affecting the percentage of early flowering of the genotypes. The first transplant season provided higher bulb productivity, whereas the second season reduced the cycle and productivity. Hybrids H1, H17 and ‘Buccaneer’ showed flowering rate lower than 3%. Among the experimental hybrids, H2 showed higher productivity when comparing with commercial cultivars, and H1, H12 and H14 were equivalent to them. However, H12 showed the highest early flowering rate (43%). Thus, considering the experimental genotypes evaluated under subtropical conditions, H1, H2, and H14, showed potential for commercial use or as potential parents in advancing the breeding program, as they stood out for presenting good yield, bulb quality and low percentage of early flowering.
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