Jim E. Wyatt, Marshall C. Smith, and Emily W. Gatch

Su and sh₂ sweet corn hybrids were tested at Ames Plantation in a replicated study in 2003. Of the su types, ‘Excalibur’ had the highest percentage of kernels {(kernel wt ÷ total ear wt)*100} when adjusted for moisture content, and the highest yield of cut corn. ‘Max’ had the highest yield of cut corn, ears per acre, ear weight, and one of the highest kernel moisture contents of the sh₂ types.

Materials and Methods

Eight su and ten sh₂-type sweet corn hybrids adapted primarily for processing were grown in two separated plantings in 2003. The two plantings were isolated by time as well as distance to prevent cross-pollination between the two types. The su hybrids were planted April 10 and the sh₂ hybrids were planted May 10, 2003, at Ames Plantation.

Experimental design of each study was a randomized complete block with four replications. Individual plots were single rows, 20 feet long and 3.3 feet apart. Plant spacing within plots was about 6-8 inches. Before planting, 600 lbs of 15-15-15 fertilizer and 4 quarts of Diazinon insecticide per acre were broadcast and incorporated. A sidedress application of ammonium nitrate was applied to supply 45 pounds of nitrogen per acre when corn was 12 to 18 inches high. Supplemental water was applied as needed with an overhead irrigation system. Production practices followed UT recommendations for sweet corn in Tennessee.

Ear heights were measured on four plants in each plot from the soil surface to the base of the top ear. A rating was made on the second planting for amount of lodging since a wind event caused some stalks to be blown down. Plots in the first planting were harvested July 3 through 9 and in the second planting July 23 through 28. Ears were harvested when kernel moisture was 72-80%. Data collected included total weight of ears, weight of a sample of five ears from each plot, ear length and diameter (5 ears), weight of cut corn (5 ears), and dry weight of cut corn from five ears. These data were used to calculate number of ears/acre, ear yield in tons/acre, percent kernel moisture, percent kernels adjusted to 72% moisture, and yield of cut corn per acre.

Data were converted to per-acre yields and subjected to analysis of variance (ANOVA) using appropriate SAS procedures. Means were separated using Duncan’s multiple range tests at P#0.05 where applicable.

su-Type Hybrids

Time from planting to harvest ranged from 80 to 86 days for su hybrids (Table 1). Those that matured at 80 and 81 days were not among the highest yielding five hybrids in the test. Highest yielding hybrids matured in 84 to 86 days. ‘Esquire’ and ‘RX 8490549’ produced the most ears per acre and ‘RX 8490549’ produced the highest tonnage of ears. ‘XP 08715864’ had significantly lower yields in terms of tonnage, possibly because of immaturity since it had also had the highest percentage of kernel moisture. All of the hybrids could probably have been harvested one to two days later and still been within the desired kernel moisture range.

Table 1. April 10, 2003, planting of su (sugary) sweet corn hybrids at Ames Plantation, spring, 2003.

zMoisture content of kernels cut from five randomly selected ears

yMeans in columns followed by the same letter are not significantly different, Duncan’s multiple range test, (P#0.05).

Small but significant differences were found between hybrids for ear diameter and length (Table 2). Ear diameter may be more important in a processing sweet corn than ear length, since two of the hybrids with smaller ear diameters also had the lowest yield of cut corn. ‘Excalibur’ had the highest percentage of kernels {(kernel wt ÷ total ear wt)*100} when adjusted for moisture content, and the highest yield of cut corn.

Table 2. April 10, 2003, planting of su (sugary) sweet corn hybrids at Ames Plantation, spring, 2003.

zInches from soil to base of top ear

yKernel moisture adjusted to 72%

xBased on number of calculated ears per acre and percent kernels cut from five randomly selected ears.

wMeans in columns followed by the same letter are not significantly different, Duncan’s multiple range test, (P#0.05).

sh₂-Type Hybrids

Time from planting to harvest ranged from 74 to 79 days for sh₂ hybrids (Table 3). The shorter maturity of sh₂ types is probably due to warmer temperatures and faster heat unit accumulation of the later planting. ‘Max’ had the highest yield of ears per acre, the highest ear weight, and one of the highest kernel moisture contents of the sh₂ types. Lodging was a problem in the second planting because of a rain storm accompanied by high winds. Hybrids which had the least amount of lodging were ‘SVR08705770’ and ‘EX 08716636’.

Table 3. May 10, 2003, planting of sh₂ (shrunken 2) sweet corn hybrids at Ames Plantation.

zMoisture content of kernels cut from five randomly selected ears

yPercent of stalks lodged

xMeans in columns followed by the same letter are not significantly different, Duncan’s multiple range test, (P#0.05).

The sh₂ hybrid with the largest ears (both diameter and length) was ‘GSS 8357’ which did not differ significantly from ‘9381178’ and ‘Max’ which had the highest percentage kernels and the highest yield of cut corn, respectively (Table 4).

Overall yields tended to be higher in the sh₂ planting compared to the su planting. This difference is probably due to growing conditions (temperature, moisture, fertility) rather than differences between types.

Table 4. May 10, 2003, planting of sh₂ (shrunken 2) sweet corn hybrids at Ames Plantation.

zInches from soil to base of top ear

yKernel moisture adjusted to 72%

xBased on number of calculated ears per acre and percent kernels cut from five randomly selected ears.

wMeans in columns followed by the same letter are not significantly different, Duncan’s multiple range test, (P#0.05).

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Copyright © 1999 by The University of Tennessee. All rights reserved.

This research represents one season's data and does not constitute recommendations.  After sufficient data is collected over the appropriate number of seasons, final recommendations will be made through research and extension publications.