The corn seeds present form and size in the spike. In the processing, the seeds are separate in function of these characteristics, and these determine regulates adjustments, they affect the type and the amount of mechanical damages, and the chemical treatment. The objective of this work was to study the effects of seed shape and chemical treatment on physiological seed quality of the hybrid corn seed "PIONEER - 32R21" produced in 1997/1998. As to obtain seeds of round and of plane shapes, seeds were separated by round screens of 8.75mm and 7.93mm respectively and then by an oblong screen of 5.1mm x 20mm. 50% of the separated seeds were treated with a mixture of Captam (75%) using a dose of 1.0g/kg seed, Deltamethrina (2.5%) 0.08ml/kg seed and Pirimiphos metil (50%) 0.03ml/kg seed, resulting in: treated round seeds, untreated round seeds, plane treated seeds and plane untreated seeds. Germination and vigor were evaluated, using electric conductivity, cold test and artificial aging. The experiment design was completely randomized with four replications (2x2 factorial) each treatment. The results showed that plane seeds of PIONEER-32R21, have better physiological quality than round seeds. Plane seeds reacted significantly better on the chemical treatment than round seeds as determined by cold test. Chemical treatment, in general, favors corn seed germination.
germination; chemical treatment; seed vigor; seed size; Zea mays
