Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 3, 2013
Publication Date: December 31, 2013
Citation: Pettigrew, W.T., Meredith, W.R., Zeng, L. 2013. Response of obsolete and modern cotton genotypes to varying plant densities. Journal of Cotton Science. 17:253-262. Interpretive Summary: With the exception of a brief price spike a few years ago, the price received for cotton lint has remained relatively stable, and in fact has not kept up with the ever increasing inputs cost for producing cotton. Producers have shown increased interest in utilizing a reduced seeding rate because increased seed costs have contributed a large portion to the overall increased input costs associated with growing cotton in the Mississippi Delta. At this point, it is not clear if diverse types of cotton genotypes would respond differently to the reduced seeding rates. The scientists in the USDA-ARS Crop Production Systems Research Unit at Stoneville, MS have conducted a four year field study evaluating whether obsolete or modern cotton varieties respond differently when grown using either a low or high seeding rate. No differences were found among varieties in their response to the different seeding rates. Modern varieties yielded more than obsolete varieties primarily because of their ability to produce more bolls per unit area. Despite growth differences, the low seeding rate produced similar yields and fiber quality to that of the higher seeding rates. Yield success can be achieved with a reduced seeding rate if uniform seedling spacing is also achieved, possibly regardless of the cultivar planted. The results from this research can be used by cotton researchers, extension specialists, consultants and producers as an unbiased source of information to aid in making cotton production decisions.
Technical Abstract: Cotton (Gossypium hirsutum L.) producers are interested in reduced seeding rates due to increasing seed costs. It is not clear whether diverse cotton genotype respond differently to reduced plant densities. This research evaluated the performance of obsolete and modern cotton genotypes grown under reduced and traditional plant population densities. The six genotypes representing 5 decades of release were grown at either 5 plants m-2 (low) or 10 plants m-2 (high) plant densities, during the years 2009-2012. Dry matter partitioning, growth analysis, yield, yield component, and fiber quality data were collected. Genotypes did not interact with plant densities for any trait. Despite few consistent dry matter partitioning or growth differences among the genotypes, large genotypic differences were detected in lint yield and fiber quality production. The obsolete genotypes had lower yields because of reduced lint percent and lint index. The higher yielding genotypes produced more bolls per unit area to generate their higher yields. Increased light interception by the high density treatment was offset by the more efficient sunlight interception and utilization by low density to result in no yield or fiber quality differences between the two densities. Yield success can be achieved with a reduced seeding rate if uniform seedling spacing is also achieved, possibly regardless of the cultivar planted.