Effect of Endosperm Type on Pericarp Thickness in Sweet Corn Inbreds1

Abstract

Sweet corn (Zea mays L.) quality is adversely affected by thick pericarp. Most cultivars of sweet corn in the USA have had sugary (su) endosperm. Recently, other endosperm mutants have become important in sweet corn improvement. Given the close relationship between endosperm and pericarp, it would be useful to determine if endosperm type has any affect on pericarp thickness. The objective of this research was to determine the effects of 10 combinations of endosperm mutants on pericarp thickness in seven sweet corn inbred backgrounds. Endosperm types that may be useful in sweet corn improvement were included. Pericarp thickness of seven sets of near‐isogenic lines that differed in endosperm composition was measured using a pressure micrometer. The endosperm mutants studied were sugary (su), dull (du), waxy (wx), sugary‐2 (su2), and shrunken‐2 (sh2). Pericarp thickness was significantly affected by inbreds, endosperm types, endosperm by inbred interactions, ear, and position of measurement on the kernel. Pericarp thickness of inbreds averaged across endosperm types ranged from 53.3 üm to 33.9 üm. Averaged across inbreds, the endosperm combination Su su2 had significantly thicker pericarp, 48 üm, than all other endosperm types. Endosperm combination su su2 had the thinnest pericarp, 38.5 üm, but was not significantly different from Su sh2 (38.7 üm), su (39.1 üm), or three of the other endosperm combinations. The thicker pericarp associated with Su su2 could adversely affect tenderness. However, the average pericarp thickness of the most widely used new endosperm type, sh2, was not significantly different than the pericarp thickness of standard (su) types, and thus would not be expected to alter pericarp tenderness of converted inbreds.