Micronutrients are used in small amounts by plants and changes in metabolic processes of seeds can improve germination and vigor; however, little is known about the effects of the combination of Zn, Co, and Mo on corn seeds. Thus, the objective of this study was to evaluate the effects of the application of Zn, Co, and Mo on the physiological potential of corn seeds of different sizes and levels of vigor. A randomized 2×2×3 factorial design was adopted, with two levels of vigor (high and low), two seed sizes (18 and 22 mm), and three doses of liquid fertilizer containing micronutrients (0, 2, and 4 mL kg-1). The physiological potential of the seeds was evaluated based on germination and vigor tests. High vigor corn seeds had greater physiological potential compared to low vigor seeds. Regarding size, small seeds (18 mm) had higher percentages of germination and vigor than the large seeds (22 mm). Seed treatment with micronutrients (Co, Mn, and Zn) resulted in improved emergence in the field, shoot length, and dry mass of large and small seeds with the application dose of 2 mL kg-1, and the application dose of 4 mL kg-1 enhanced emergence in the field of large seeds and germination after the cold test of low vigor seeds of both sizes.

Seeds are the primary input in the maize production process, and monitoring seeds through the processing stages is an essential practice in the production chain, particularly when identifying critical points in the process that can interfere with the final seed quality. Therefore, the objective of this study was to evaluate the effect of processing stages in the physiological quality of Balu 761 maize hybrid seeds. Seeds from the Balu 761 maize hybrid obtained during processing (receipt, shelling, drying, threshing, grading and bagging) were used. The experimental design was completely randomized with four replications. Physiological seed quality was evaluated using germination, accelerated aging, cold testing, electrical conductivity and seedling length tests, with the latter used to determine the length and dry weight of the shoot and root. The data were subjected to a variance analysis, and the means were compared using the Scott-Knott test (p≤0.05). The physiological quality of Balu 761 maize hybrid seeds was enhanced during processing because the percentage of normal seedlings from cold test, as well as the root length, shoot length and shoot dry weight were optimized when considering the process as a whole, which contributed to the increased vigor of both seeds and seedlings. The germination and accelerated aging tests were not influenced by the processing stages.

Detasseling is an essential practice in maize seed production to obtain hybrids. Due the difficulty in carrying out the detasseling in a standardized way, the objective of this study was to evaluate the yield and physiological quality of maize seeds after using detasseling techniques in two cropping seasons. The experiment was carried out in Pitangueiras - PR, using corn progenitors of the commercial hybrid Balu 761. The experimental design was randomized blocks with 4 replications. The factorial scheme was 6 × 2, with 6 detasseling techniques: removal of the tassel only (D0); tassel removal + 1 sheet (D1); tassel removal + 2 leaves (D2); tassel removal + 3 leaves (D3); tassel removal + 4 leaves (D4); and tassel removal + 5 leaves (D5), and 2 cropping seasons: cropping season 1 (2014) and cropping season 2 (2015). The variables analyzed were: seed yield (kg ha-1), germination (%) and seed vigor from the accelerated aging (%) and cold test (%). The results showed that detasseling of maize progenitors of the Balu 761 hybrid must be carried out with the removal of the tassel only, considering that the removal of leaves during this practice is capable of reducing seed yield by up to 25%. The removal of the tassel with up to five leaves does not affect the physiological quality of the maize seeds. The cropping season influenced the seed yield, as well as seed germination and vigor from the cold test