Phytosanitary quality of Brachiaria brizantha ‘BRS Piatã’ seeds in function of climate conditions

Abstract

Infected seeds are one of the main pathogen transmission vehicles, and they are responsible for significant losses in production fields; phytosanitary defense depends on the inoculum and climatic factors. Thus, in this study, it was aimed to identify climatic variables of the regions that propitiate the production of Brachiaria brizantha 'BRS Piatã' seeds infected with phytopathogenic fungi. Temperature and rainfall data were obtained from 10 production fields, and phytosanitary quality of the seeds was evaluated with the filter paper method; the means were compared using the Kruskal-Wallis non-parametric analysis. Principal component analysis was performed to determine the relationship between the climatic variables and seed phytosanitary quality. Sites with maximum temperatures higher than 30 °C, mean values close to 25 °C, and rainfall less than 82 mm during harvest were favorable to the incidence of Fusarium spp. The incidence of Bipolaris sp. in the seeds of Piatã grass was favored by temperatures around 19 and 20 °C during the maturation phase. The highest incidence of Exserohilum sp. occurred at the sites in which the temperature during harvest was close to 20 °C and accumulated rainfall, between 167 and 181 mm.Qualidade sanitária de sementes de Brachiaria brizantha 'BRS Piatã' em função de condições climáticas RESUMO: A semente infectada é um dos principais veículos de transmissão de patógenos, responsáveis por perdas significativas em campos de produção e, as condições sanitárias destas dependem do inóculo e dos fatores climáticos presentes. Assim, objetivou-se identificar variáveis climáticas das regiões que propiciam a produção de sementes de Brachiaria brizantha, cv. BRS 'Piatã' , infectadas com fungos fitopatogênicos. Foram obtidos dados de temperatura e precipitação de 10 campos de produção e a sanidade das sementes foi avaliada pelo método do papel de filtro, com as médias comparadas pela análise não-paramétrica de Kruskal-Wallis. Para determinar a relação entre variáveis climáticas e a sanidade das sementes aplicou-se a análise de componentes principais. Locais com temperaturas máximas superiores a 30 °C, médias próximas a 25 °C e acúmulo de chuva inferior a 82 mm na colheita foram favoráveis à incidência de Fusarium spp.. A incidência de Bipolaris sp. em sementes de capim-piatã na fase de maturação é favorecida por temperaturas em torno de 19 e 20 °C. A maior incidência de Exserohilum sp. ocorre em locais cuja temperatura durante a colheita é próxima a 20 °C e a precipitação pluviométrica acumulada situa-se entre 167 e 181 mm.

Ethanol test as a determinant of physiological potential of forest species seeds: The case of Plathymenia reticulata Benth. (Leguminosae-Mimosoideae), a tree of interest for Atlantic Forest restoration

“…This technique has been used in seed technology research with the aim of clarifying the relationships between the different variables evaluating physiological potential. Moreover, it has been successfully used for soybean seeds (Barbosa et al, 2013), forage grasses of the Brachiaria genus (Silva et al, 2017;Silva et al, 2019), and caupi beans (Mendonça et al, 2018).…”

Germination and Vigor of Soybean and Corn Seeds Treated with Mixed Mineral Fertilizers

“…These values are similar to those found in studies on the physiological and sanitary quality of Urochloa brizantha cv. BRS Piatã [ 34 , 35 ].…”

“…The multivariate data analysis methods allow a global study of these variables, evidencing the connections, similarities, or differences between them with the least possible loss of information [ 26 , 29 , 30 , 31 , 34 ].…”

Components of seed production and ergot resistance used as criteria for selection of Brachiaria hybrids

“…Molecular studies confirmed the identification of C. maximensis and Brachiaria grasses in Brazil (Chaves, Gomes, Marriel, & Pfenning, 2004), and recent studies show that 50% commercial seed lots of B. brizantha cv. Piatã collected in 10 seed production fields (two seed production fields in each state of Brazil: SP, GO, BA, MG and MS) were infected with more than one species of Claviceps (Silva, Martins, Nascimento, Barreto, & Farias, 2019). The association of pathogens to seeds can affect plant establishment, development, seed production, forage persistence in the field and animal production.…”

“…The use of fungicides in the soil may reduce the presence of the pathogen (Fernandes, Verzignassi, Mallmann, & Queiroz, 2017;Dung et al, 2018), but the selection of resistant forage grasses would be the most effective management (Miedaner & Geiger, 2015). Considering that Brazil is the leading producer and exporter of tropical seeds of forage grasses in the world (Silva et al, 2019), the commercialization of contaminated seed lots can affect mainly the foreign market, due to restrictions on the presence of Claviceps spp. in many countries.…”