Sementes de soja infectadas por Cercospora kikuchii, sob déficit hídrico

Abstract

ResumoO desempenho de sementes de soja e o estabelecimento da cultura em campo podem ser afetados negativamente pela contaminação das sementes por fitopatógenos, principalmente quando as sementes não encontram condições ideais de germinação. Objetivou-se avaliar, neste trabalho, o desempenho de sementes de soja com diferentes níveis de manchamento por Cercospora kikuchii e a eficiência de tratamentos com fungicidas, quando as sementes foram submetidas a déficit hídrico. Sementes foram selecionadas e classificadas quanto à intensidade de manchamento por C. kikuchii, em três categorias: sementes sem sintomas ou sem manchas (zero), sementes com 1 a 25% e com 26 a 50% da superfície manchada (mancha-púrpura). Em seguida, foram incubadas em meio de restrição hídrica por manitol e submetidas, ou não, a tratamentos com as misturas fungicidas thiabendazole+thiram e carbendazin+thiram. Em laboratório, procedeu-se à análise das sementes por meio dos testes de germinação, frio e de sanidade (Blotter). Ambos os tratamentos fungicidas não erradicaram Cercospora kikuchii quando as sementes se apresentaram com sintomas; entretanto, aumentaram o desempenho fisiológico das mesmas sob estresse hídrico. Em condições de déficit hídrico, durante a germinação, a incidência de manchamento por Cercospora kikuchii, em sementes de soja, aumenta a porcentagem de plântulas anormais infectadas. Palavras-chave adicionais:Glycine max; mancha-púrpura; tratamento químico. AbstractThe soybean seeds performance and the plants establishment in the field may be affected negatively by the contamination of the seeds with phytopatogens, especially under unfavorable conditions for seeds germination. The objective was to evaluate the soybean seeds performance with different stain purple levels and the fungicide treatment efficiency when the seeds are submitted to hydric deficit stress conditions. The seeds were selected and classified by staining intensity in: seeds without stains (zero), 1 to 25% and 26 to 50% of the seed surface with purple stain. The seeds were incubated in medium with hydric restriction using mannitol and treated or nottreated with thiabendazol + thiram and carbendazin + thiram fungicides mixtures. In the laboratory the physiologic conditions of the seeds were evaluated by germination, cold and sanity tests. Both chemical treatments did not eradicate the pathogen when the seeds presented high contamination level but they increased physiological performance of the soybean seeds under hydric stress. During germination under water stress conditions, the incidence of Cercospora kikuchii in soybeans increases the abnormal seedlings infected percentage.

Artificial Intelligence and Multiple Models Applied to Phytosanitary and Nutritional Aspects That Interfer in the Physiological Potential of Soybean Seeds

“…The results obtained for the nutrients (Figure 1a) were as follows: calcium (Ca) of 2.7 mg kg -1 , being similar to the value exposed by Brunini et al (2016) in 11 soybean cultivars, where it varied from 0.22 to 0.27 g 100g -1 . The values obtained for the magnesium (Mg) and sulfur (S) nutrients are 2.3 and 2.1 mg kg -1 similar to those shown also by Brunini et al (2016) in soybean cultivars, which ranged from 0.23 to 0.31 g 100g -1 for Mg and 0.21 to 0.30 g 100g -1 for S. Regarding the levels of pathogens, Cercospora kikuchii (CEK) was the most evident among the 1.6% diseases, however, it had an extremely lower occurrence when compared with the results of Pereira et al (2017) who used soybean seed samples with 8.68%, 70.10% and 85.30% incidence of the pathogen. It is noteworthy the superior tolerance of new genotypes under development.…”

“…Pathogens such as Bacteriosis, Fusarium semisectum and Cercospora kikuchii, when present, indicate an unfavorable effect on seed germination, corresponding to the result found by Pereira et al (2017). The incidence of Cercospora kikuchii increases the incidence of abnormal seedlings in germination who state that there is a 12.8% reduction in germination, when compared to seeds with and without the incidence of the pathogen.…”

“…The incidence of Cercospora kikuchii increases the incidence of abnormal seedlings in germination who state that there is a 12.8% reduction in germination, when compared to seeds with and without the incidence of the pathogen. The same was highlighted by Pereira et al (2017), where seeds contaminated with Cercospora kikuchii, when treated with fungicides, had a lower incidence of abnormal seedlings, due to the effective control of the pathogen. In the analysis of accelerated aging, the nutrients Mo, Na and Zn follow the same negative correlation as in germination, as well as the pathogens Aspergillus flavus, Bacteriosis, Fusarium semisectum and Cercospora kikuchii.…”

Qualidade Fisiológica De Sementes De Soja Oriundas De Distintos Estratos Da Planta

“…Rocha et al (2014), comprovaram através de teste de vigor de comprimento de plântula que lotes de sementes de soja infectados pelo fungo Aspergillus ochraceus com incidência acima de 50% apresentam grandes perdas de vigor e deterioração dos seus tecidos. Desta forma, o tratamento de sementes é de extrema importância para a viabilidade das mesmas (PEREIRA et al, 2017).…”

Soybean sowing under low water availability conditions: impacts of seed treatment and soil management

“…In the absence of ideal conditions, soybean germination and emergence occur more slowly, providing fungi found in the soil and in the seed itself with a greater opportunity for attack, so they can cause seed deterioration or even seedling death. In order to minimize such deleterious effects, it is recommended to treat seeds with fungicides (Pereira et al, 2017).…”