Abstract:
Studies were conducted in 1976 and 1977 on the effects of harvest
dates on maturity, yields and sugar content of four cultivars of
sweet corn. The cultivars were 'Golden Cross Bantam', 'Jubilee',
'Rapidpak' and 'Tendertreat'. Moisture content of kernels ranged from
80 to 67 per cent for the six harvest dates.
A regression technique was used to estimate relationships of
yield, percent moisture in kernels and sugar content to the six harvest
dates. Relationships of yield and sugar content to percent moisture,
content in kernels were also estimated.
Yield of husked, acceptable (good) ears, which was used as a
standard of yield estimation, was increased by a delay in harvest.
The increase averaged 0.135 tons per acre for each day's delay in harvest
for three cultivars in 1976 and 0.152 tons per acre per day in
1977. No evidence of linear or quadratic relationships between yield
and harvest date were found for 'Tendertreat'.
Kernel moisture loss was highly correlated with harvest date and
degree hours. Kernel moisture loss averaged 0.687 per cent for each
day's delay in harvest in 1976 and 0.577 per cent per day in 1977.
Yield increases averaged 0.173 tons per acre for each one percent drop
in moisture content of kernels for three cultivars in 1976 and 0.264
tons per acre percent moisture drop of kernels in 1977.
Quantitative analysis of sugar content in kernel samples that
had been frozen was made by using a gas chromatography technique.
Total sugar and sucrose contents dropped most rapidly at early harvests, then decreased slowly. Average rate of sucrose decline was 0.579
per cent for each day of delay of harvest in 1976 and 0.226 per cent
per day in 1977. Total sugar decreases averaged 0.589 per cent for
each one percent drop in moisture content of kernels in 1976 and 0.304
per cent with each per cent moisture drop of kernels in 1977. Reducing
sugar decreased rapidly as harvest was delayed and fructose decreased
faster than glucose. There were differences in cultivars in
initial sugar content and rapidity of loss as maturity progressed. It
appears that a 1:10 ratio of fructose to sucrose may be related to
good quality of kernels.
The use of the accumulated heat unit system for predicting optimum
maturity showed no increase in precision over the use of the number
of days from planting to harvest.
Proper timing of harvest and selection of cultivars need to be
made, as well as giving consideration to other factors, to achieve optimum
yields and sugar content of sweet corn.
