Camilo de Lelis Morello

Comparação de métodos para avaliar a adaptabilidade e estabilidade produtiva em algodoeiro

The objective of this work was to compare different methods used to estimate adaptability and stability of 17 cotton genotypes evaluated in 23 locations of the Brazilian savannah. Genotype and environment effects and genotype x environment interaction were significant. According to ecovalence and AMMI models, cultivar BRS Cedro showed the best stability. Varieties Delta Penta and BRS Ipe were among the most unstable genotypes, but not among the most productive. Using the methods of Eberhart & Russel, Lin & Binns and Annicchiarico, genotypes BRS 269 - Buriti, FMT 701 and CNPA GO 2001-999 were the most stable and among the five most productive on average. The evaluation of the specific adaptabilities provided by the AMMI analysis is of great importance in the study of the behavior of genotypes. The amount of information generated and the facilities of interpretation favors Lin & Binns method, which can be complemented by an AMMI analysis.

1-Methylcyclopropene and Aminoethoxyvinylglycine effects on yield components of field-grown cotton

A ocorrencia de estresses bioticos e abioticos pode alterar o balanco hormonal e desencadear a ativacao de vias envolvidas nas respostas do algodoeiro a estresses, resultando na abscisao de botoes, flores e macas em desenvolvimento e em menor rendimento de algodao em caroco e de fibras. Como parte desses mecanismos que primariamente regulam as respostas protetivas da planta contra estresses, o etileno e considerado um hormonio chave, envolvido nessas respostas e aumentos em seu nivel de sintese tem sido verificados em plantas submetidas a quaisquer tipos de estresse. Assim, o desenvolvimento de estrategias objetivando mitigar os seus efeitos negativos poderia reduzir a taxa de queda de estruturas reprodutivas e impactar positivamente na produtividade de fibras. Com esse proposito, 1-methylcyclopropeno (1-MCP), um composto inibidor da acao do etileno e aminoethoxyvinylglycina (AVG), um inibidor da sua sintese foram aplicados sobre o algodoeiro para investigar seus efeitos sobre o rendimento de algodao em caroco, de fibras, a percentagem de fibras e o stand final de plantas durante duas estacoes de crescimento (2010 e 2011). Assim, experimentos a campo em delineamento blocos casualizados completo com cinco repeticoes foram conduzidos. Os resultados obtidos evidenciam que os inibidores da sintese e da acao de etileno aumentaram o rendimento de algodao em caroco e de fibras em ambas as estacoes de crescimento. Os resultados obtidos pelo uso do AVG aplicado na fase reprodutiva inicial (primeiro botao floral) evidenciaram os maiores valores para os componentes de rendimento analisados, sendo os primeiros resultados obtidos no Brasil com tal proposito.

Distância genética entre linhagens avançadas de germoplasma de algodão com uso de marcadores de RAPD e microssatélites

The objective of this work was to select similarity coefficients to be used among sets of cotton genotypes with low genetic diversity. Sixty-five lineages and four cotton cultivars were analyzed by RAPD and SSR markers; and the genetic similarity was estimated by seven similarity coefficients: Simple Matching, Rogers & Tanimoto, Ochiai, Hamman, Jaccard, Dice and Russel & Rao. The adequacy of the use of each coefficient to the collected data was verified by correlation between the distance matrices, the consensus index between the dendrograms and the Tochers optimization method. The coefficient of Russel & Rao was the most divergent, and its use is not recommended. Among the parameters used to estimate the quality of information provided by each coefficient, differences were observed only by the consensus index, which established two groups: one in which simultaneous absence of bands are taken into account, and other in which it is excluded. Considering the presence of only two microsatellite alleles per polymorphic locus and the higher consensus index coefficients, the Simple Matching, Hamman and Rogers & Tanimoto coefficients should be preferred when analyzing cotton elite genotypes with low genetic similarity.

Mechanism of resistance and presence of different resistance genes to Ramularia areola in two cotton genotypes

Earlier studies showed that the resistance of cotton genotype FMT 02102996 to Ramularia areola is governed by one dominant gene. More recently, the resistance of another genotype CNPA BA 2003-2059 to R. areola was detected under field and glasshouse conditions. Present investigation was conducted to verify the mechanism of resistance of the genotype CNPA BA 2003-2059 and to find out if the resistance of these two genotypes is governed by the same or by different genes. Segregating plant populations derived from the cross between the resistant genotype CNPA BA 2003-2059 and the susceptible genotype FMT 701, the back cross populations, as well as those derived from the cross between the two resistant genotypes were evaluated for disease severity by artificial inoculations under glasshouse conditions. The ratio of plants segregating for resistance and susceptibility was studied by χ2 test. The results indicated that the resistance to R. areola in genotype CNPA BA 2003-2059 is governed by one dominant gene and that the resistance in each one of the resistant genotypes is governed by a different dominant gene. These results may assist the local breeding programs aimed at pyramiding resistance genes to this pathogen and may form the basis for genetic mapping of resistance genes.

BRS 336: a high-quality fiber upland cotton cultivar for Brazilian savanna and semi-arid conditions

Cotton cultivar BRS 336 is a high-quality fiber upland cultivar and has wide adaptation to the Brazilian growing areas, with resistance to bacterial blight. BRS 336 exhibited fiber length higher than 32.0 mm in all field tests. Also, fiber strength exceeded all upland cotton currently grown in Brazil.

Um método simples e rápido de seleção para resistência à murcha-de-fusário em genótipos de algodoeiro

This study describes a new method to screen cotton genotypes for wilt resistance caused by Fusarium oxysporum f. sp. vasinfectum. Cotton genotypes were sown in germination trays (25 mL each cell) with sterilized vermiculite. On the fifth and the seventh days after germination, each seedling was inoculated with a suspension adjusted to 5 x 105 spores/mL. Resistance was evaluated using 1) the area under disease progress curve (AUDPC), for 15 days starting on the tenth day after the first inoculation (DAI); 2) disease severity on the 25th DAI; 3) percent of seedlings showing vascular system browning and 4) percent of seedlings with pathogen in the vascular system on the 25th DAI. No significant differences were found among genotypes Clevewilt 6, Auburn 56-24, Bayou SM-1, Coker 312, Stoneville 132, IAC RM2 and BJ 1302 for AUDPC and disease severity. When considering disease severity, genotypes Auburn 56-24, coker 312 and Bayou SM-1 were more resistant than Deltapine 45A, whereas for AUDPC only Coker 312 and Bayou SM-1 were more resistant than Deltapine 45A. Coker 312 was more resistant than Acala 44 only for disease severity. There was a significant correlation between AUDPC and disease severity, however, due to its ease, the latter index was found to be the best to screen cotton genotypes for fusarium wilt resistance.

Ramularia areola sporulation potential in Brazilian cotton

A mancha de ramularia causada por Ramularia areola e uma das mais importantes doencas para a cultura do algodoeiro no Brasil. Para o controle efetivo da doenca, sao necessarias 5-9 aplicacoes de fungicidas em cultivares suscetiveis. O objetivo do presente trabalho foi avaliar, in vitro e in vivo, o potencial de esporulacao de isolados de R. areola, originarios de diferentes regioes do Brasil, sob diferentes regimes de temperaturas. A producao de esporos foi avaliada em laboratorio e em folhas de plantas de oito cultivares de algodoeiro em condicoes de casa-de-vegetacao. Os resultados obtidos in vitro indicaram que o potencial de producao de esporos foi dependente da temperatura. A maxima esporulacao do fungo ocorreu com 17oC para isolados originarios do Estado de Sao Paulo e 23oC para isolados de Goias e Mato Grosso. No estudo in vivo, houve variacao na esporulacao em funcao da cultivar e do isolado. A maioria dos isolados apresentou alta agressividade na cultivar FM 966 LL e DELTAOPAL. Com os resultados obtidos, e possivel indicar uso mais racional de fungicidas, cultivares que apresentaram menor esporulacao do fungo, alem de formar base para novos estudos com relacao a variabilidade desse fungo em algodoeiro no Brasil. Esse e o primeiro relato sobre o potencial de esporulacao de isolados brasileiros de R. areola.

Efeito de diferentes níveis de Colletotrichum gossypii South var. cephalosporioides Costa, em plantas de algodão no campo e sua incidência nas sementes

The transmission of Colletotrichum gossypii var. cephalosporioides from plant to seeds of cotton, normally, does not have correlation with disease severity in the field. However, low incidence of the disease, sometimes is associated with high infection of the pathogen in the seeds that is one of the causes of rejection of seed production fields in some regions of Brazil. This research had the objective to evaluate the effect of source of inoculum from diseased plants, in relation to incidence of ramulosis when 70% of bolls were developed and the relation between the incidence of disease in the field and the infection of cotton seeds. The experiments were carried out during two seasons in 2006 and 2007 with 0,0; 0,1; 0,2; 0,4; 0,8 and 1,6% of incidence, 40 days after emergence in randomized blocks with four repetitions and parcels of eight planted lines of 15 m of lenght. The incidence of disease was evaluated when 70% of bolls were completely developed in 200 plants in the four central lines. After the harvest the seeds were submitted to health test through the blotter method. It was verified high correlation between initial inoculum and incidence of disease when 70% of bolls were developed and incidence of disease in the field and infection of cotton seeds by the pathogen. The correlation was higher in 2006 than in 2007. Seed production fields with incidence of disease higher than 5% can cause high incidence of the pathogen in the cotton seeds.

Classification of individual cotton seeds with respect to variety using near-infrared hyperspectral imaging

This paper proposes the use of Near Infrared Hyperspectral Imaging (NIR-HSI) as a new strategy for fast and non-destructive classification of cotton seeds with respect to variety. A total of 807 seeds of four different cotton varieties are employed in this study. For classification purposes, each seed is represented by an average spectrum obtained by coaveraging the pixel spectra of the NIR-HSI image. Conventional NIR and VIS-NIR spectra are also employed for comparison. By using Partial-Least-Squares Discriminant Analysis (PLS-DA), correct classification rates of 98.0%, 89.7% and 91.7% were achieved in the NIR-HSI, conventional NIR and conventional VIS-NIR datasets. The superiority of the NIR-HSI system can be ascribed to a more comprehensive scan of the seed area, as compared to the conventional VIS-NIR spectrometer.

Carbon isotope fractionation for cotton genotype selection

The objective of this work was to evaluate the carbon isotope fractionation as a phenomic facility for cotton selection in contrasting environments and to assess its relationship with yield components. The experiments were carried out in a randomized block design, with four replicates, in the municipalities of Santa Helena de Goias (SHGO) and Montividiu (MONT), in the state of Goias, Brazil. The analysis of carbon isotope discrimination (Δ) was performed in 15 breeding lines and three cultivars. Subsequently, the root growth kinetic and root system architecture from the selected genotypes were determined. In both locations, Δ analyses were suitable to discriminate cotton genotypes. There was a positive correlation between Δ and seed‑cotton yield in SHGO, where water deficit was more severe. In this site, the negative correlations found between Δ and fiber percentage indicate an integrative effect of gas exchange on Δ and its association with yield components. As for root robustness and growth kinetic, the GO 05 809 genotype performance contributes to sustain the highest values of Δ found in MONT, where edaphoclimatic conditions were more suitable for cotton. The use of Δ analysis as a phenomic facility can help to select cotton genotypes, in order to obtain plants with higher efficiency for gas exchange and water use.