Cotton Seeding Rate Effects on Plant Architecture and Lint Yield across Different Varieties in the Upper Southeast Coastal Plain

The trial was conducted as a randomized complete block design with four replication of each treatment. The treatment design was a split plot design with plant populations as the whole plots and varieties as the sup-plots. The plant populations to be tested were 14,520, 21,780, 29,040, 36,300, and 43,560 plants per acre. The varieties were selected based on the five most commonly grown varieties in Virginia during 2016: Phytogen 333WRF, Phytogen 499WRF, Stoneville 4946GLB2, Deltapine 1522 B2RF, and Deltapine 1538 B2RF. Final plant populations ranged from 11,761 to 30,637 plants per acre across seeding rates for varieties tested. As seeding rates increased final plant populations also increased during the 2017 study with the 3 seeds per row foot having the greatest plant populations during the study. For the purpose of this report only differences in seeding rate effects will be discussed as varieties performed similarly across seeding rates. There were differences in lint yield among varieties and differences among some plant architecture components, however there were sparse interactions between seeding rate and cotton variety. Lint yields across varieties averaged 1,533 lb lint per acre for the 1 seed per row foot up to 1,777 lb lint per acre for the 3 seed per row foot seeding rate. This increase is most likely due to optimum rainfall and optimum boll retention during the study at the higher plant populations. At the seeding rate of 1 seed per row foot boll retention at harvest on the 1st position fruit was almost 90% from the 1st to 9th fruiting branches. On the 2nd and 3rd position fruit, boll retention was 75% and 38% on fruiting branches 1-3 and decreased to 36% and 7% on fruiting branches 7-9 .