Reaction of Cenchrus accessions to Pyricularia grisea in the semiarid region of Pernambuco

Abstract

The fungus Pyricularia grisea causes leaf spots on buffel grass (Cenchrus ciliaris). This fungus is a major problem in this forage pastures in Texas, USA and northern Mexico. Although this disease does not present serious problems to buffel grass in the Brazilian semiarid region, the search for germplasm with some level of tolerance to this disease is always important before they cause problems for the crop. The aim of this study was to evaluate the reaction of accessions of the Cenchrus spp. to the P. grisea, in natural infection. Twenty accessions belonging to the Germplasm Bank (BAG) of Cenchrus da Embrapa Semiárido were evaluated, in randomized blocks with three replications and a plot containing 20 plants. The evaluations were carried out in two evaluation cycles in 2019 and 2020, in the rainy season, when the environmental conditions for the development of the disease were favorable. To assess the severity of the disease, a scale of scores ranging from 1 to 4 was used. The average data of the scores per plot were submitted to analysis of variance and the averages were compared by the Scott and Knott test, at 5% significance. There was a significant effect on disease tolerance. Ten accesses received an average score above 3 (CPATSA 83476; CPATSA 79151; CPATSA 79150; CPATSA 79591; CPATSA 90194; CPATSA 79144; CPATSA 79558; CPATSA 79134; CPATSA 90570; CPATSA 79613), in both assessments, indicating a moderate resistance in relation to the susceptible witness, the cultivar Biloela. There is variability to be explored for the reaction to P. grisea in the Cenchrus BAG from Embrapa Semiárido.