Gurpreet Virk

Success stories of wide row cotton production have generated producer interest across the cotton belt. The objective of this study was to quantify the effect of row spacing on (1) cotton growth and development and (2) lint yield and fiber quality in Georgia. The cotton cultivar Deltapine DP 1646 (Bollgard 2, XtendFlex; Bayer Crop Science) was planted in 2021 and 2022 in Tifton, GA, at row spacings of 91 cm, 122 cm, 152 cm, and 183 cm. Although canopy closure was delayed in wider row spacings compared to the 91‐cm spacing, all other crop growth and development trends did not differ among row spacings. Similarly, row spacing had no effect on the incidence of boll rot/hard lock. The 91‐cm row spacing yielded 1734 kg lint ha −1 . The 183‐cm row spacing reduced yield by 15% compared with the grower's standard row spacing of 91 cm. Fiber quality parameters did not differ among row spacing treatments. Seed costs can be reduced in all wide row systems evaluated for cotton, and the 122 and 152‐cm row spacings had similar yields to the 91‐cm row spacing. However, Georgia growers produce peanuts ( Arachis hypogea L.) and corn ( Zea mays L.), the most common rotational crops for cotton producers, using a 91‐cm row spacing. Consequently, the simplest transition to wide row production would be the 183‐cm spacing, which incurred yield penalties in the current study. Thus, a 91‐cm row spacing is still the most feasible option for Georgia cotton producers.

Cultivar variation in seed characteristics can affect seedling vigor, and nitrogen (N) availability influences early‐season growth in some instances. However, interactions between cultivar and N application rate for early‐season growth have received limited attention. Thus, the objectives of this research were to quantify the effects of cultivar, N‐application rate, and their interaction on early‐season growth, predict seedling vigor from plant morphology, and identify associations between early‐season crop growth rates (CGR) and other growth indices. To this end, a 2‐year (2018 and 2019) field study was conducted using six cotton cultivars having different seed characteristics and six different N‐application rates. In both years, all single‐plant and whole‐crop growth indices were affected by cultivar but not early‐season N‐application rates. A function was developed that was strongly predictive ( R 2 = 0.78) of seedling dry weight and utilized only plant height and mainstem node assessments. Leaf area index was a strong and consistent predictor of early‐season CGR, whereas net assimilation rate was only associated with CGR in one of the 2 years. Thus, it is concluded that of the two factors assessed in the current study, cultivar is the dominant driver of seedling vigor up to 35 days after planting. Additionally, leaf area development is a more consistent driver of early‐season CGR than average assimilation rates of the canopy. In contrast, an application of N at planting did not affect seedling vigor or early‐season canopy growth in cotton.