Measuring Thickness of Excised Mature Corn Pericarp¹

Pericarp thickness of 19 corn ( Zea mays L.) samples was determined by two methods: by microscope and by micrometer. Either kernels were frozen and 40 µ sections cut, stained, and measured with an ocular micrometer or kernels were presoaked and pericarp strips were excised for measurement. The excised strips were measured with a plunger micrometer. The coefficient of rank correlation was +0.85**, indicating good agreement between the two methods. The microscopic method produced greater thickness values than the micrometer method. The lower values were probably due to a certain amount of compression by the micrometer plunger. Germinal‐abgerminal ratios differed while right and left sides of the kernels were similar. The excision method is the more economical of the two and does not need specially trained laboratory technicians.