SEED QUALITY DISCRIMINATION IN COWPEA: THE SENSITIVITY OF SEEDLING MORPHOLOGY VS. THE STANDARD GERMINATION TEST

Abstract

The physiological quality of seeds is a determining factor for the initial establishment of cowpea (Vigna unguiculata (L.) Walp.), a crop of food, social, and economic importance in tropical regions of Brazil. Differences among local materials may affect germination, the proportion of non-germinated seeds, and the occurrence of abnormal seedlings, with direct implications for stand establishment. This study aimed to evaluate the physiological quality of cowpea seeds from the Branco, Manteiga, and Pingo de Ouro materials, based on the proportional distribution of germination, non-germinated seeds, and abnormal seedlings. The experiment was conducted under laboratory conditions at the Gurupi Campus of the Federal University of Tocantins in 2022, using a completely randomized design with three materials and four replications of 50 seeds. The germination test was performed on germitest paper rolls maintained at 25 °C, according to the Brazilian Rules for Seed Testing, with evaluation carried out six days after sowing. The data were proportionally organized so that the sum of the categories germination, non-germinated seeds, and abnormal seedlings corresponded to 100% for each material. Manteiga showed the highest proportional germination percentage, with 57.87%, followed by Branco, with 48.83%, and Pingo de Ouro, with 28.64%. The highest proportion of non-germinated seeds was observed in Branco, with 45.07%, whereas Pingo de Ouro showed the highest percentage of abnormal seedlings, with 32.68%. The results indicate that the assessment of the physiological quality of cowpea seeds should consider not only germination but also the occurrence of non-germinated seeds and abnormal seedlings. It is concluded that Manteiga showed the best proportional germination performance, Branco had the lowest occurrence of abnormal seedlings, and Pingo de Ouro demonstrated greater physiological and/or sanitary limitation. It is recommended that the evaluation be complemented with vigor tests, seed health analysis, and repetition of the study with a larger number of lots and crop seasons.