Growing temperature is known to affect the grain yield and quality of
maize. Two genetically unrelated normal dent maize inbreds, ICI63 and
ICI92, with different heterotic backgrounds were grown in a greenhouse
with the ears wrapped in temperature control devices set at 25 and 35
degrees C during the grain-filling period. Grain yield, kernel weight
, and kernel density were less for ears at 35 degrees C than for those
at 25 degrees C. The extent of the loss, however, varied with the var
iety: 13.1 and 37.9% kernel weight loss and 8.47 and 10.08% density lo
ss for ICI63 and ICI92, respectively. The starch granular shape of ICI
63 became more oval-shaped, but there was no shape change for ICI92. A
s developmental temperature increased, starch granule size decreased a
nd gelatinization temperature increased. With increasing developmental
temperature, the true amylose content of ICI63, determined by iodine
affinity, decreased 2.39% and that for ICI92 decreased 2.20%; amylose
molecular size of both varieties also decreased. Size exclusion chroma
tography and high-performance anion-exchange chromatography revealed a
n increased medium branch-chain fraction and decreased long and short
branch-chain fractions for ICI63 amylopectin, whereas ICI92 amylopecti
n had increased long and medium branch-chain fractions and a decreased
short branch-chain fraction, when the ear developed at 35 degrees C.