Response of selected plant characteristics of a normal and a shrunken-2 sweet corn cultivar to fertilizer nitrogen

In 1986 and 1987, 'Silver Queen' and 'How Sweet It Is' sweet corn cultivars were grown using three rates of nitrogen fertilization at the Plateau Experiment Station, Crossville, Tennessee. The nitrogen rates were 100, 135, or 200 kg*ha^-1 in 1986 and 67, 135, or 200 in 1987. Yield in dozens, yield in weight, ear weight, plant height, stalk diameter, ear height, plant stand, ear number per plant, tissue nitrogen concentration, ear length, ear diameter, and percent grain, plus pH and °Brix of kernel extract and firmness of kernel pericarp tissue were measured during both years.

More rainfall was received early in the 1987 season than in 1986, with more uniform distribution throughout the year. Growing degree day accumulation differed little between the two years with 23 more days in 1986 than in 1987. Overall, climatic conditions appeared to have little effect on the results between years.

In 1986, 'How Sweet It Is' out-yielded 'Silver Queen' in ear number, total weight, individual ear weight, and ear number per plant, and had larger diameter ears. 'Silver Queen' grew taller and larger in stalk diameter, set ears higher, had longer ears, plus had a higher pH and °Brix of kernel extract and firmness of kernel pericarp tissue than did 'How Sweet It Is'.

In 1987, 'Silver Queen' yielded more in ear number, total weight, individual ear weight, grew taller, set ears higher, had a higher plant density and had a higher pH and °Brix reading for kernel extract than did 'How Sweet It Is'. 'How Sweet It Is' had a higher ear leaf nitrogen concentration than 'Silver Queen'.

The cultivar differences between years appears to be related to the quality of the 'Silver Queen' seed used in 1986. The overall vigor of the plants was much lower and not typical of the cultivar in 1986, while in 1987 the seeds germinated more consistently and the plants had a vigorous appearance throughout the growing season.

Nitrogen fertilization had little effect on any of the characteristics measured. Perhaps the organic matter plowed into the soil each spring provided enough nitrogen, from mineralization throughout the growing season, to mask the effects of added nitrogen.