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Drought stress and nitrogen (N) deficiency are important abiotic stresses that severely limit net photosynthetic rate (AN). A number of studies have investigated the underlying physiological limitations to AN in response to water deficit or N deficiency; however, the relative sensitivities of photosynthetic component processes and carbon loss processes to combined drought and N deficiency in field‐grown cotton (Gossypium hirsutum L.) have not been explored. Therefore, the objective of the present study was to determine the effects of combined water deficit and nitrogen deficiency on the underlying physiological processes driving AN in field‐grown cotton. Water‐deficit stress caused substantial reductions in AN, but reductions in AN were greater under optimum N conditions (74%) than under N deficiency (22%). Decreased CO2 diffusion, RuBP regeneration, and Rubisco carboxylation were major contributors to a decline in AN due to water‐deficit stress. Reductions in Rubisco carboxylation and RuBP regeneration were the greatest drivers of N deficiency‐induced decline in AN. Lower CO2 diffusion and Rubisco carboxylation were main constraints to AN due to combined water deficit and N deficiency. Regarding carbon loss processes, both dark respiration and photorespiration under water‐deficit stress or N deficiency, and only photorespiration under combined water deficit and N deficiency, contributed to declines in AN. Increased non‐photochemical quenching and/or photorespiration prevented photoinhibition of photosystem II under stress conditions. Overall, response of photosynthesis to water‐deficit stress was dependent on N availability, and rate‐limiting physiological processes contributing to declines in AN were dependent on the type of prevailing stress. Core Ideas: Response of photosynthesis to water‐deficit stress was dependent on nitrogen rate.CO2 diffusion, RuBP regeneration, and Rubisco carboxylation were major limitations to photosynthesis under water deficit.Rubisco carboxylation and RuBP regeneration co‐limited photosynthesis under nitrogen deficiency conditions.CO2 diffusion and Rubisco carboxylation limited photosynthesis under combined water deficit and nitrogen deficiency.Non‐photochemical quenching and/or photorespiration prevented photodamage to photosystem II under stress conditions. [ABSTRACT FROM AUTHOR]

Various tillage systems have limitations on soil health, such as the degradation of soil structure and organic matter under conventional tillage (CT) systems, as well as shortterm soil compaction in conservation tillage systems. A 3-year field experiment was established to evaluate the integration of cover crop (CC) and organic amendments (OAs) into CT and strip tillage (ST) systems, and their impact on soil properties and cotton (Gossypium hirsutum L.) productivity. The CC was cereal rye (Secale cereale), and the combined application of animal manure and biochar constituted the OA. In the third year, differences in soil compaction between the CT and ST systems were observed when the measurements were made after tillage. Moreover, integrating CC and OA under the CT and ST systems increased the soil depth to compaction zones. Soil compaction was observed at 27.5-cm depth under CT, at 30- cm depth under CT integrated with CC and OA, at 10-cm depth under ST, and at 15-cm depth under ST integrated with CC and OA, using 2 MPa as the threshold. In general, the integration of CC and OA tended to increase soil respiration, organic matter, and available nutrients, but the effects were not consistent across years and soil depth. Despite differences in the various soil health properties, the management systems had minimum impact on cotton productivity and fiber quality, indicating the ST was effective in preparing the seedbed. Moreover, the differences in soil properties were not at yield-limiting levels within 3 years of the study [ABSTRACT FROM AUTHOR]

With grower interest in skip and wide row cotton systems, varietal performance in such systems has become a major question. An experiment was conducted in 2022 and 2023 in Tifton and Midville, GA, evaluating three row arrangements (standard 91‐cm row spacing, 2 × 1 skip row, and 183‐cm row spacing or wide row) and four commercially available varieties (Stoneville [ST] 5091 Bollgard 3 Xtendflex [B3XF], Phytogen [PHY] 400 Widestrike 3 Roundup Flex Enlist [W3FE], DynaGro [DG] 3799 B3XF, and Deltapine [DP] 1840 B3XF). There were no interactions between variety and row arrangement for any response variable, indicating the best variety for standard row spacings would also be the best variety in alternative row arrangements. Plant populations were reduced 32% and 53% in 2 × 1 skip‐row and wide‐row systems, respectively, compared to standard row arrangements, which accomplishes the major goal of these systems in reducing seed cost. Boll rot and hard lock were reduced in wide row treatments only, which could benefit cotton growers in the lower Southeast. However, reductions in lint yield were associated with 2 × 1 skip row (all site years) and wide row arrangements (three out of four site‐years) compared to the grower standard. Differences among varieties were observed in plant heights, lint yield, and fiber quality, which is to be expected. These results confirm much of the work conducted on skip and wide row cotton systems and indicate that for growers in the lower Southeast to achieve maximum lint yields, standard row arrangements are superior to alternative row arrangements. Core Ideas: Cotton growers remain interested in skip‐ and wide‐row systems to reduce input costs.Plant population was reduced 32% and 53% in 2 × 1 skip and wide row treatments, respectively.Boll rot and hard lock was reduced in wide row arrangements, but not in 2 × 1 skip row treatments.In all four site‐years, lint yield was reduced in 2 × 1 skip row arrangements by 14%–32%.In three out of four site‐years, lint yield was reduced in wide row arrangements by 13%–31%. [ABSTRACT FROM AUTHOR]

Understanding the complex interactions between genotype-environment dynamics is fundamental for optimizing crop improvement. However, traditional phenotyping methods limit assessments to the end of the growing season, restricting continuous crop monitoring. To address this limitation, we developed a methodology for spatiotemporal registration of time-series 3D point cloud data, enabling field phenotyping over time for accurate crop growth tracking. Leveraging multi-scan terrestrial laser scanning (TLS), we captured high-resolution 3D LiDAR data in a cotton breeding field across various stages of the growing season to generate fourdimensional (4D) crop models, seamlessly integrating spatial and temporal dimensions. Our registration procedure involved an initial pairwise terrain-based matching for rough alignment, followed by a bird's-eye view adjustment for fine registration. Point clouds collected throughout nine sessions across the growing season were successfully registered both spatially and temporally, with average registration errors of approximately 3 cm. We used the generated 4D models to monitor canopy height (CH) and volume (CV) for eleven cotton genotypes over two months. The consistent height reference established via our spatiotemporal registration process enabled precise estimations of CH (R² = 0.95, RMSE = 7.6 cm). Additionally, we analyzed the relationship between CV and the interception of photosynthetically active radiation (IPARf), finding that it followed a curve with exponential saturation, consistent with theoretical models, with a standard error of regression (SER) of 11%. In addition, we compared mathematical models from the Richards family of sigmoid curves for crop growth modeling, finding that the logistic model effectively captured CH and CV evolution, aiding in identifying significant genotype differences. Our novel TLS-based digital phenotyping methodology enhances precision and efficiency in field phenotyping over time, advancing plant phenomics and empowering efficient decision-making for crop improvement efforts. [ABSTRACT FROM AUTHOR]

In this study, we investigated the potential involvement of endogenous viral elements (EVEs) in the development of apical tissue necrosis, resulting in the terminal abortion of upland cotton (Gossypium hirsutum L.) in Georgia. The high-throughput sequence analysis of symptomatic and asymptomatic plant tissue samples revealed near-complete EVE-Georgia (EVE-GA) sequences closely related to caulimoviruses. The analysis of EVE-GA's putative open reading frames (ORFs) compared to cotton virus A and endogenous cotton pararetroviral elements (eCPRVE) revealed their similarity in putative ORFs 1–4. However, in the ORF 5 and ORF 6 encoding putative coat protein and reverse transcriptase, respectively, the sequences from EVE-GA have stop codons similar to eCPRVE sequences from Mississippi. In silico mining of the cotton genome database using EVE-GA as a query uncovered near-complete viral sequence insertions in the genomes of G. hirsutum species (~7 kb) but partial in G. tomentosum (~5.3 kb) and G. mustelinum (~5.1 kb) species. Furthermore, cotton EVEs' episomal forms and messenger RNA (mRNA) transcripts were detected in both symptomatic and asymptomatic plants collected from cotton fields. No significant yield difference was observed between symptomatic and asymptomatic plants of the two varieties evaluated in the experimental plot. Additionally, EVEs were also detected in cotton seeds and seedlings. This study emphasizes the need for future research on EVE sequences, their coding capacity, and any potential role in host immunity or pathogenicity. [ABSTRACT FROM AUTHOR]

Cotton (Gossypium hirsutum L.) lint yield and fiber quality are associated with various yield components. Research efforts addressing intra‐boll yield component contributors to lint production boll−1 are limited. Thus, a study was conducted in Tifton, Georgia with the objectives to quantify the contributions of intra‐boll yield components to lint production boll−1 and to identify yield components most strongly associated with lint production boll−1 in advanced breeding lines of upland cotton. Data collected included intra‐boll yield components and fiber quality parameters. A strong association was observed between lint production boll−1 and seedcotton weight boll−1 (r = 0.896) compared to lint production boll−1 and lint percent (LP, r = 0.574). For breeding lines with maximum lint weight boll−1, the contribution of seedcotton weight and LP ranged from 0.17 to 0.36 g boll−1 and 0.22 to 0.24 g boll−1, respectively, suggesting a relatively greater influence of seedcotton weight boll−1 on lint weight boll−1. Lint production boll−1 can be expressed as the product of seeds per boll, seed surface area, fiber density (FD), and individual fiber weight (IFW). IFW was the greatest contributor to lint production boll−1 for seven breeding lines and FD for nine breeding lines. A strong positive association was observed between lint production boll−1 and IFW (r = 0.656, p < 0.001); however, no significant association between lint weight boll−1 and FD suggesting a relatively greater influence of IFW on lint weight boll−1. Our work provides future direction aimed at improving lint yields through the selection of various yield components. Core Ideas: Significant genetic differences exist for all measured parameters except seeds per boll.Seedcotton weight boll‐1 has a relatively greater influence on lint weight boll‐1 compared to lint percent.Individual fiber weight has a greater influence on lint weight boll‐1 compared to fiber density and seed surface area. [ABSTRACT FROM AUTHOR]