INCIDENCE OF FUNGI IN MOMBASA GRASS SEEDS DURING THE STAGES OF THE SEED CONDITIONING PROCESS

Givanildo Z Da Silva,Tatiane S Jeromini,Cibele C Martins,Lilian F De Melo,Rita De C Panizzi

doi:10.1590/1809-4430-eng.agric.v39n2p234-239/2019

Givanildo Z Da Silva, Tatiane S Jeromini + Show 3 more

Open Access

https://doi.org/10.1590/1809-4430-eng.agric.v39n2p234-239/2019

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Abstract

ABSTRACT The objective of this study was to evaluate the effect of the seed conditioning process on the sanitary quality of Panicum maximum ‘Mombasa’ seeds. The seeds were sampled before processing and after exiting the seed blower and sieves (discharge from the top and bottom sieves), first gravity separator (intermediate discharge), seed treatment equipment (dyeing the seeds of the intermediate discharge from the first separator), and second gravity separator (upper, intermediate, and lower discharge). Sanitary analysis was performed by the Blotter Test method with and without surface disinfestation of the seeds, which were incubated at 20 ± 2 °C, with a photoperiod of 12 h, for 7 d. The conditioning process increased the incidence of Fusarium sp. in the Mombasa grass seeds. In addition, Cladosporium sp. and Alternaria sp. were found in and on the surface of the seeds and, therefore, can be disseminated by the seed conditioning machines. The percentage of seeds with Alternaria sp. decreased after dyeing and after the top discharge of the second gravity separator stage.

Highlights

With the expansion of pastures and intensification of livestock activity in recent years, several diseases have begun to occur and cause losses in forage grass productivity, especially in central-western and northern Brazil; contaminated seeds are a method of introduction and dispersal of pathogens, causing forage diseases in these regions, and in areas that were previously free of these pathogens (Mallmann et al, 2013).The pathogens present in seeds can affect germination, seedling development, and the longevity and production of forage plants in the field
Some important and potentially pathogenic fungi have been detected in the seeds of P. maximum and Brachiaria spp., such as Curvularia, Phoma, Fusarium, Exserohilum, Cercospora, and Helminthosporium
The other samples were taken from various stages of the conditioning process, as described below: Seed blower and sieves: after passing through the seed blower and sieves, the CP2 sample was collected from the discharged material retained in the upper sieve, which was a round sieve with a diameter of 7/32 of inch (5.56 mm)

Summary

Introduction

The pathogens present in seeds can affect germination, seedling development, and the longevity and production of forage plants in the field. Panicum maximum is an important forage crop but little is known about the dissemination of pathogens by seeds and its effects (Marcos et al, 2015). Some important and potentially pathogenic fungi have been detected in the seeds of P. maximum and Brachiaria spp. Other fungi such as Alternaria, Aspergillus, Cladosporium, Epicoccum, Nigrospora, Penicillium, and Trichoderma, which are considered secondary and storage fungi, have been detected (Martinez et al, 2010; Pereira et al, 2012; Mallmann et al, 2013; Marcos et al, 2015)

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