EVALUATION OF PHYTOSANITARY ASPECTS OF RICE CULTIVATION (Oryza sativa L.) AND PATHOGENS ASSOCIATED WITH THE SEED AND GRAIN

Abstract

Rice cultivation is susceptible to numerous diseases that damage various plant organs, including the seed, negatively impacting productivity and product quality. The aim of this study was to evaluate diseases and pathogens associated with certified seeds and grains in plantations in the state of Portuguesa, Venezuela, to provide relevant results that can inform sanitary measures within management strategies. The experimental phase was conducted in the field and laboratory using the Payara 1 and SD20A varieties. Germination tests, seed health analyses, and pathogen isolations were performed using leaf samples exhibiting disease symptoms. Endophytic relationships between potential seed-associated pathogens in rice seedlings were also determined. The results identified the genera Fusarium, Curvularia, Alternaria, Helminthosporium complex (H. complex), and Nigrospora as potential phytopathogenic fungi in plants, seeds, and grains. While Aspergillus spp., Penicillium sp., Cladosporium sp., Rhizopus sp., and Mucor sp., potential storage pathogens, were found at low frequencies, indicating adequate storage site management. The germination percentages of Payara 1 and SD20A seeds were 84 % and 85 %, respectively, according to reference values for certified seeds. Curvularia (6.25 %) and Fusarium (4.75 %) were found associated with the seeds of both varieties. There were significant differences between the two genotypes evaluated for the presence of endophytic microorganisms; Payara 1 showed a higher prevalence of Fusarium and Curvularia, and SD20A showed a higher prevalence of bacteria.