Avaliação do estado de contaminação de sementes de arroz (Oryza sativa L.) por fungos na província de Gaza

Abstract

Fungal contamination of rice seeds (Oryza sativa L.) represents a major challenge to production and food security, with limited information available on this issue in Gaza Province. This study aimed to evaluate the level of fungal contamination in rice seeds from three districts of the province (Chókwè, Chongoene, and Manjacaze). Specifically, the study assessed the phytosanitary condition of the seeds based on visual parameters (discoloured grains, empty grains, presence of insects and mycelium), identified the associated fungal species, and determined the levels of fungal contamination among districts. A total of 20 samples of approximately 1 kg each were collected from small local producers, representing different rice varieties cultivated in the region. The samples were subjected to the manual reduction method and incubated in a moist chamber, followed by observation under a stereomicroscope and microscope at the Plant Pathology Laboratory of Eduardo Mondlane University. Fungal identification was performed using moist chamber and slide culture techniques, allowing observation of the morphological structures characteristic of each species. Results revealed variation in contamination levels among districts. The frequency of discoloured grains was 20%, 18%, and 9% for Manjacaze, Chókwè, and Chongoene, respectively, while empty grains accounted for 12%, 8%, and 5%. All samples also showed the presence of hollow seeds, insects, and visible mycelium. Eight main fungal species were identified: Fusarium sp., Aspergillus flavus, A. niger, Penicillium chrysogenum, Rhizopus sp., R. stolonifera, Alternaria sp., and Microdochium oryzae. ANOVA followed by Tukey’s test (5%) revealed significant differences among districts, with higher contamination in Manjacaze, intermediate levels in Chókwè, and lower in Chongoene. It is concluded that fungal contamination is associated with environmental conditions and post-harvest handling practices, highlighting the need for good agricultural and storage practices and continuous phytosanitary monitoring.