Evaluating Upland Cotton Maturity Patterns in the Northern Texas High Plains

Emily Brorman, West Texas A&M University; Guillermo Marcillo, West Texas A&M University; Jourdan Bell, Texas A&M AgriLife Research; and Craig Bednarz, Texas A&M AgriLife Research and West Texas A&M University. 

Summary

• This study investigated cotton growth in the Texas Northern High Plains (NHP) and compared it to the Target Development Curve (TDC), which was developed in Arkansas in the early 1990s.

• Compared to the TDC, cotton in the NHP requires at least one additional week to reach key growth stages like first square and first flower. 

• Cotton plants in the NHP also grow slower between first square and first flower, which results in reduced early season vegetative growth and fewer fruiting nodes at first flower. 

• Rather than the traditional TDC cutout of Nodes Above White Flower (NAWF) = 5, this research suggests NAWF=4 as a benchmark for physiological cutout in the NHP.

• This benchmark may be appropriate for other cotton-growing areas in the High Plains such as Oklahoma and Kansas.

Introduction

The Ogallala Aquifer serves as the primary source of irrigation groundwater in the NHP (Colaizzi et al. 2009). As irrigation capacities decline, farmers in the area have opted to grow cotton, a crop more tolerant to drought than corn (Howell et al. 2004). Thus, cotton acres have steadily increased not only in the NHP, but also in the Oklahoma Panhandle and Western Kansas. However, because of their higher altitude and latitude, these regions have a shorter growing season and accumulate fewer growing degree days (GDD) than other production regions of the U.S. Cotton Belt. While earlier-maturing cultivars and improved management strategies help, farmers still need more precise information on cotton development under these unique environmental conditions.    

The current standard for monitoring cotton growth and development in the U.S. Cotton Belt is the Target Development Curve (TDC), developed by the University of Arkansas in the early 1990s (Figure 1; Bourland et al. 2008). Developmental target values for key growth stages, including first square, first flower, and physiological cutout, are presented in the COTMAN manual (Oosterhuis & Kerby 2008). However, because environmental and management conditions in the NHP differ significantly from those in Arkansas, the accuracy of the TDC in this region should be evaluated. 

Research Goals

• This study evaluated how the TDC can be used for modern cotton cultivars in the NHP and provides updated benchmarks for improved crop management for the region.   

The Research

Eight commercially available cotton cultivars were studied in 2022 and 2023. In 2022, maturity patterns among the eight cultivars were similar, so the data were combined and presented as the average across all eight cultivars. However, in 2023, one cultivar exhibited a distinct maturity pattern, and thus data for each cultivar being presented separately.        

Accumulated heat units (HU) from planting to 120 days after planting (DAP) were greater in 2022 than in 2023 at the trial site near Etter, TX (Figure 2). Total heat unit accumulation was 234 GDD higher in 2022, with most of the differences occurring during the first 40 days after planting.

Cotton growth and development were delayed in both years compared to the TDC (Figure 1). The average number of days from planting to first square was 42.6 DAP in 2022, which was closer to the TDC benchmark of 35 DAP than in 2023, when it ranged from 44.7 to 46.7 DAP across cultivars. Accumulated HU from planting to first square were also higher in 2022, totaling 541.4 GDD, compared to 316.5 to 342.3 GDD in 2023. As indicated earlier, lower HU accumulation in 2023 contributed to additional delays in reaching first square stage.   

The time to first flower was delayed in both seasons compared to the TDC (Figure 3). In 2022, first flower occurred at 70 DAP, while in 2023 it ranged from 75 to 80 DAP. The nodal development rate (i.e., days between successive main stem nodes) was slower than the TDC rate of 2.7 days per node (Figure 3). In 2022, the average was 3.6 days per node, and in 2023 it ranged from 4.1 to 5.0 days across cultivars. Again, the lower HU accumulation in 2023 likely contributed to the slower nodal development.

According to the TDC, the number of fruiting nodes at first flower under optimum growth conditions is 9.25 (Figure 1). In this study, the number of fruiting nodes present at first flower was 7.7 in 2022 and ranged from 6.9 to 8.0 across cultivars in 2023. These lower values reflect the slower nodal development rate and limited early-season vegetative growth observed in both years. 

In this study, physiological cutout was defined as the NAWF value corresponding to the main stem node at which 95% of maximum lint yield was achieved. To determine this point, lint yield data were combined with white flower tag data to calculate the percentage of maximum yield at each main stem node and its associated NAWF value (Table 1). In 2022, 95.3% of maximum yield was achieved at main stem node 16, with an average NAWF value of 3.3. In 2023, 96.6% of maximum yield was achieved at main stem node 17, with an average NAWF value of 4.0.

Table 1. Nodes above white flower values and mainstem node of the last effective boll populations in studies conducted in 2022 and 2023 in the Texas Northern High Plains.

A proposed TDC for the NHP was developed by combining data across years and cultivars (Figure 3). Compared to the Bourland et al. (2008) TDC, the results indicate that (1) first square occurs at approximately 46 DAP, (2) nodal development rate from first square to first flower is about 4.4 days per node, (3) first flower occurs at approximately 78 DAP with approximately 7.3 nodes above white flower, and (4) physiological cutout (NAWF=4.0) occurs at approximately 91 DAP. 

Conclusions

This study provides updated benchmarks for cotton production in the NHP. Development from planting to first square was delayed at least one week compared to the TDC. Additionally, the nodal development rate from first square to first flower was slower than indicated by the TDC, resulting in fewer fruiting nodes at first flower. The time from planting to first flower was also extended compared to the TDC, with further delays in 2023 due to lower HU accumulation.      

Yield data by main stem node and NAWF value suggest physiological maturity in the NHP is delayed by about one to two weeks when compared to the TDC. In this study, cutout occurred at NAWF = 3.3 in 2022, and 4.0 in 2023, both lower than the TDC benchmark of NAWF= 5.0. Therefore, a range of NAWF = 3.0 to 4.0 may serve as a more appropriate benchmark for physiological cutout in the NHP and possibly other cotton-producing areas in Oklahoma and Kansas. 

References

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This research was based on the following thesis

Brorman, E., & West Texas A & M University. Department of Agricultural Sciences. (2024). Evaluating Cotton (Gossypium Hirsutum L.) Maturity Patterns in The Northern Texas High Plains. West Texas A&M University. Article | Google Scholar

Acknowledgements

Authors

Emily Brorman, West Texas A&M University; Guillermo Marcillo, West Texas A&M University; Jourdan Bell, Texas A&M AgriLife Research; and Craig Bednarz, Texas A&M AgriLife Research and West Texas A&M University.

Reviewers

Travis Faske, University of Arkansas and Daren Mueller, Iowa State University

Sponsors

This study was funded by USDA Ogallala Aquifer Program agreement 58-3090-0-011 and Cotton Incorporated grant 23-903.

How to cite: Brorman, E., Marcillo, G., Bell, J., and Bednarz, C. 2025. Evaluating Upland Cotton Maturity Patterns in the Northern Texas High Plains. Crop Protection Network. CPN-5019. doi.org/10.31274/cpn-20251118-0.