Relationship between seed harvesting method and seed physiological quality for a number of Pioneer maize hybrids

摘要

The seed germination and seed vigor of eight Pioneer Hi-Bred maize hybrids were evaluated immediately after harvestingudand a year later. The aim was to determine whether the seed showed loss of germination and vigor whenudshelled mechanically. The seed was cleaned but not dressed, and then germinated according to the ISTA standardudprocedure in four seed analysis laboratories. In addition, the seed of two randomly chosen hybrids was dividedudinto four fractions based on size and shape, and the germination of each fraction was examined separately. All theudgermination results were acceptable according to the ISTA (2010) standard (over 90%), but a higher germinationudpercentage was observed after manual shelling than after mechanical shelling. The number of abnormal seedlings,udhowever, was higher for mechanically shelled seeds than for those harvested as whole ears. When the seed ofudseparate seed fractions was tested, the germination percentage was lowest for the medium-sized round fractionudand highest for the large flat fraction. The seed vigor of three of the hybrids was highest when maize seeds wereudharvested shelled rather than on the ear. For all the hybrids the germination percentage was lower for both groupsudwhen analyzed a year after harvesting. Better germination results were obtained for all the hybrids after whole earudharvesting than in the shelled group, but the difference was not significant. In the vigor tests the results obtainedudfor mechanically shelled seed were superior to those for whole ear harvesting for the same three hybrids, but againudthe difference was not significant. The experiments should be repeated over several years to determine whetherudmechanically shelling maize seed negatively affects seed germination and vigor.