Development and Yield of Upland Cotton Grown Using Different Tillage Systems in Virginia.

Tillage studies were conducted in Suffolk, Virginia from 2013-2016 comparing the effects of conventional, minimal, no tillage, and strip tillage on the growth, development, and yield of four contemporary varieties. Phytogen 499 WRF, Deltapine 1321 B2RF, Deltapine 1028 B2RF, and Fibermax 1944 GLB2 were assessed for responses in stand establishment, plant height, total nodes, nodes above white flower (NAWF), soil compaction, lint yield, and lint quality in a split-plot design. Soil compaction was greatest in the no-till treatment with depths to a root restrictive layer ranging from 7.62 - 12.7 cm, resulting in shorter plant heights compared to other tillage methods. Significant differences in plant heights (P < 0.05) between tillage treatments were observed weekly staring at the fifth week after planting in both the 2013 and 2014 study. Deltapine 1321 B2RF had consistently high plant heights in all years, with significant varietal differences being present in all sampling intervals for 2014 and 2015. In-season plant development seemed to be impacted more by varietal differences than tillage. No-till resulted in slightly lower yields compared to other tillage treatments, however no significant differences in lint yields were observed in any year based on tillage, but were for variety in 2013 and 2014. Deltapine 1321 B2RF yielded highest with lint yields of 1,746 kg ha^-1, 1,467 kg ha^-1, and 693 kg ha^-1 during 2013, 2014, and 2015 respectively. Differences in lint quality factors were strongly influenced by variety, however tillage was only observed to effect micronaire with differences in 2013 (P = 0.0064).  There was no tillage by variety interaction in any year, supporting the idea that varieties respond similarly across tillage systems.