To determine the effects of variations in plants/hill, within-row plant spacings, and plant populations on the agronomic and fiber properties of cotton (Gossypium hirsutum L.), we evaluated the performance of ‘Deltapine 16’ when planted in hills and drilled at five populations over a 3-year period (1969-71). Hills were spaced 38 cm apart. The hills were thinned by hand to one, three, five, seven, and nine plants/hill, representing a range in population of 24,700 to 222,300 plants/ha. Plants in the drill plantings were spaced approximately 38.0, 12.7, 7.6, 5.3, and 4.3 cm apart to provide approximately the same populations for the hill-dropped and drill-planting method.
Significant differences in yield due to populations were found, but planting method had no significant influence on yield. The highest yields each year were obtained in a population range of 70,000 to 121,000 plants/ha. In 2 out of 3 years the highest yields were obtained with a population of 114,000 to 121,000 plants/ha (five plants/hill or plants spaced 7.6 cm apart). Significant differences in lint percentage, boll size, and seed index were due to populations. The combined data indicate no appreciable differences in lint percentage; lint percentage of the low population, however, was significantly higher than that of the two highest populations in 2 of the 3 years. Boll size gradually decreased as plant population increased, with the lowest population usually producing significantly larger bolls and seed.
We found that plant populations had no consistent effects on fiber length, strength, and elongation. The differences were small in magnitude and of no practical value. Micronaire tended to decrease as population increased.