Review Reports - Modeling the Effects of Climate Change on Potato Production in Myanmar Using DSSAT

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Introduction Section

Correct the line spacing errors noted on page 3 (lines 107-110).
A brief transitional paragraph should be added immediately following the research objectives to ensure a logical and coherent linkage to Section 2 (Materials and Methods).
The rationale for limiting the study to a single geographic area and considering only one crop variety requires a more robust defense. The authors must explicitly acknowledge that the resulting recommendations are inherently variety-specific and discuss the implications for generalizability.
The exclusive focus on rainfed cropping conditions should be justified. Since Table 3 presents a comparative analysis of irrigated and rainfed potato productivity, the potential contribution of irrigation management practicesto enhanced potato production under future climate scenarios merits discussion.
The analysis must incorporate a discussion of the influence of the recent military coup and escalating inflation rates on the cost of agricultural inputs, providing a comprehensive context for production decisions.

Section 2: Materials and Methods

Ensure that Figure 1 is appropriately positioned and integrated with the main body text where it is first referenced.
The citation style requires meticulous review. Non-specific references, such as "Crop management data from [7]," which lack immediate author identification, must be corrected to conform to the journal's required academic citation protocol (e.g., Author, Year).

Section 3: Results

The statement on page 14, lines 421-422, must be elucidated with greater precision to fully convey its technical significance.
Section 3.1 (Climate Data): The average baseline and projected temperature values should be clearly presented and discussed within the main narrative of the text, not solely in tables or figures.
Section 3.3 (Yield Variability): The analysis of climate change effects on potato yield must include a focused discussion on the causes of yield fluctuation and a specific examination of the factors contributing to the potential lowest yields observed in certain projected years.
Section 3.5.3 (Cost-Benefit Analysis - CBA): The methodology employed for the Cost-Benefit Analysis (CBA)should be briefly detailed, explicitly stating the interest rate and the discounted time horizon used in the calculation.

Section 4: Discussion

The interpretation presented on page 16, lines 520-522, requires a more precise and elaborate explanation to clearly articulate the intended scientific conclusion.
The discussion on page 16, lines 529-532, which addresses cooler temperatures, must be expanded to explicitly explain the study's application or consideration of both low (cooler) and high temperature extremes in the context of the crop model or analysis.
Study Limitations and Future Research:

This section should outline future research directions, such as advocating for longitudinal studies or investigating the heterogeneous climate change impacts across different agro-ecological zones of Shan State.
The limitations inherent in using a single study site and one crop variety must be critically discussed, comparing the approach to insights potentially gained from broader experimental trials and designs.

The authors must critically analyze the impact of post-Coup market fluctuations on agricultural practices, incorporating recent data and scholarly references. This analysis should specifically address how these economic factors may modulate the utilization of fertilizers and consequently influence crop yields.

Section 5: Conclusions

The statement on lines 653-655 is overly general and lacks specificity. The authors must clearly articulate howthe SUBSTOR model's simulation of potato growth specifically elucidates the effects of climate change and variability in the study region.
Given the described climate of the study region (cool winters, warm summers), the recommendation for developing heat-resistant varieties must be explicitly justified. The conclusion should clearly demonstrate why the projected temperature changes necessitate this specific, high-level adaptation strategy.

Author Response

Dear Reviewer,
We appreciate your valuable comments and suggestions on our manuscript. Your feedback has been important in helping us improve our manuscript. We have revised our manuscript by addressing the suggested points. Please see the details below and in the revised manuscript.

Does the introduction provide sufficient background and include all relevant references? (Can be improved)
We appreciate the reviewer’s comment. After carefully re-evaluating the Introduction section, we believe that it already provides sufficient background to frame the study. The introduction outlines the global and national importance of potatoes for food security, highlights their role as a key cash crop in Myanmar, and summarizes documented climate-change impacts on potato production. It also presents the broader context of climate change in Myanmar, introduces DSSAT as a widely used crop modelling tool for assessing climate impacts and adaptation strategies, and identifies existing national efforts to address climate change. Furthermore, the section emphasizes the gap in research related specifically to potatoes under future climate scenarios in Myanmar, which justifies the need for this study. Relevant and appropriate references have been included throughout. Accordingly, no changes were made to this section.

Are the results clearly presented? (Can be improved)
Thank you for the comment. We have revised the Results section for enhanced clarity and presentation, and it is now improved.

Are the conclusions supported by the results? (Can be improved)
Thank you for the comment. We have revised the Conclusions section to improve clarity and alignment with the results, and it is now stronger and better supported by our findings.

The English could be improved to more clearly express the research.
We have improved language clarity throughout the manuscript to ensure effective communication of our research findings

The authors must validate and clearly articulate the hypothesized link between the proposed adaptation strategies and future potato yields within the graphic abstract. This linkage requires explicit justification.
We thank the reviewer for this important comment. We have revised the graphic abstract to show the linkage between adaptation strategies and projected yields explicitly. The revised graphic abstract now includes the adaptation strategies we have applied and their effects on future potato yield.

Introduction Section

Correct the line spacing errors noted on page 3 (lines 107-110).
Thank you for pointing this out. The line spacing inconsistencies have been corrected in the revised manuscript. (Page 3, lines 109)

A brief transitional paragraph should be added immediately following the research objectives to ensure a logical and coherent linkage to Section 2 (Materials and Methods).
Thank you for the suggestion. A transitional paragraph has been added after the research objectives to improve the logical flow and strengthen the linkage to Section 2 (Materials and Methods) in the revised manuscript (page 4, lines 139-142)

The rationale for limiting the study to a single geographic area and considering only one crop variety requires a more robust defense. The authors must explicitly acknowledge that the resulting recommendations are inherently variety-specific and discuss the implications for generalizability.
We thank the reviewer for this important observation regarding the geographic and varietal scope of our study. We agree that explicitly acknowledging these limitations and their implications for generalizability strengthens the manuscript. (On pages 20, lines 777-789)

The exclusive focus on rainfed cropping conditions should be justified. Since Table 3 presents a comparative analysis of irrigated and rainfed potato productivity, the potential contribution of irrigation management practices to enhanced potato production under future climate scenarios merits discussion.
We thank the reviewer for this constructive comment. While both irrigated (summer) and rainfed (post-monsoon) crop seasons were used during model calibration to improve parameter reliability, the climate change simulations in this study were intentionally limited to rainfed conditions. This focus aligns with the primary objective of evaluating the climate impacts on the predominant production system in Southern Shan State, where potato cultivation is primarily rainfed, and smallholders typically lack reliable access to irrigation infrastructure. In addition, projecting future irrigated yields would require assumptions regarding future water availability, infrastructure expansion, and investment conditions, which are beyond the scope of the current assessment and would add substantial uncertainty to the projections.

We agree that irrigation management has important potential for reducing climate-induced yield losses. Therefore, a paragraph has been added to the manuscript discussing the role of irrigation as a possible adaptation strategy. However, its feasibility depends on the availability of local water resources. Future research should include scenario-based simulations that incorporate different irrigation strategies to evaluate their benefits and trade-offs under changing climate conditions.

We have revised the manuscript accordingly (page 16, lines 575-585)

The analysis must incorporate a discussion of the influence of the recent military coup and escalating inflation rates on the cost of agricultural inputs, providing a comprehensive context for production decisions.
We appreciate the reviewer's valuable comment. We agree that post-coup inflation and political instability have likely impacted the costs of agricultural inputs. However, reliable and consistent data reflecting these recent changes were not available for the duration of our study. As a result, including this analysis would involve making assumptions that go beyond the scope of our research. We recognize this as an important area for future investigation.

Section 2: Materials and Methods

Ensure that Figure 1 is appropriately positioned and integrated with the main body text where it is first referenced.
Thank you for the observation. We have repositioned Figure 1.

The citation style requires meticulous review. Non-specific references, such as "Crop management data from [7]," which lack immediate author identification, must be corrected to conform to the journal's required academic citation protocol (e.g., Author, Year).
We thank the reviewer for this comment. We understand the concern regarding citation clarity. While we have followed the journal's numbered citation format as specified in the author guidelines, we recognize that key references benefit from author identification in the text. We have revised the manuscript to include author names alongside citation numbers for major data sources and frequently referenced works (e.g., "Pronk et al., [7]" rather than "[7]" alone). This maintains compliance with the journal's bracket notation system while improving immediate source identification for readers. We have also corrected any formatting inconsistencies in the citation brackets throughout the manuscript.

Section 3: Results

The statement on page 14, lines 421-422, must be elucidated with greater precision to fully convey its technical significance.
We thank the reviewer for highlighting this. We have revised this to provide a more precise technical explanation of the tuber formation dynamics and their physiological significance. (Page 14, lines 452-454)

Section 3.1 (Climate Data): The average baseline and projected temperature values should be clearly presented and discussed within the main narrative of the text, not solely in tables or figures.
We have updated with the values of temperatures for both the baseline and the projected ones within the main narrative of the text. (Page 9, lines 306-311)

Section 3.3 (Yield Variability): The analysis of climate change effects on potato yield must include a focused discussion on the causes of yield fluctuation and a specific examination of the factors contributing to the potential lowest yields observed in certain projected years.
We thank the reviewer for this valuable suggestion to strengthen our analysis of yield fluctuations and low-yield events. We have revised Section 3.3 to include a focused discussion on the causes of yield variability and a detailed examination of factors contributing to the lowest yields in specific projected years.

We have added the analysis of daily climate conditions contributing to the potential lowest yields projected in 2044 (ssp126), 2054 (ssp245), and 2048 (ssp585) against the high-yield year (2050). (page 12, lines 377 and 381-390)
We now explicitly analyze the climate factors driving yield fluctuations, with particular focus on temperature and rainfall patterns during critical growth stages for highest- and lowest-yield years, including:

Quantitative temperature data showing maximum temperatures of 28.8-29.0°C during tuber initiation in low-yield years versus 27.1-27.5°C in 2050.
Rainfall deficits during the critical tuber initiation period (45-55 DAP), with low-yield years receiving 7-37.1 mm compared to 23-49.3 mm in 2050.
Physiological mechanisms linking these climate stresses to reduced tuber set and yield accumulation

We also have emphasized how the timing of climate variables relative to crop phenological stages (particularly tuber initiation) determines final tuber yield. Please see revised text on pages 17 and 18 (lines 631-659)

Section 3.5.3 (Cost-Benefit Analysis - CBA): The methodology employed for the Cost-Benefit Analysis (CBA)should be briefly detailed, explicitly stating the interest rate and the discounted time horizon used in the calculation.
We thank the reviewer for this valuable comment regarding the methodological transparency of our cost-benefit analysis. We have now revised Section 3.5.3 to provide clearer methodological details.

The analysis presented is a comparative economic assessment conducted within a single growing season. We compared production costs and economic returns between two scenarios using baseline production data from Aung et al.,2018

Without Adaptation (W/O): Baseline fertilizer cost of USD 676/ha, total production cost of USD 2,187/ha
With Adaptation (W): 50% increase in fertilizer application (USD 1,014/ha), resulting in total production cost of USD 2,525/ha

Since both scenarios operate within the same production year and assume identical yield outcomes (18.16 t/ha) and the same market prices, no discount rate or extended time horizon was applied. The analysis focuses on within-season cost differences and their impact on net profit, which decreased from USD 1,929/ha to USD 1,591/ha (a 17.5% reduction) despite the increased fertilizer input.

We believe this revision provides the methodological clarity the reviewer requested while accurately representing the single-season comparative nature of the analysis. The revised passage is on page 15, lines 507-515.

Section 4: Discussion

The interpretation presented on page 16, lines 520-522, requires a more precise and elaborate explanation to clearly articulate the intended scientific conclusion.
Thank you for the valuable comment. The explanation has been expanded to provide a clearer scientific interpretation. The revised text now clarifies that the differences in yield outcomes between the two studies may be attributed to variations in crop duration, with the previous study employing an 89-day growth cycle compared to 79 days in the current study. The extended growth period (10 days) in the earlier study likely allowed more time for tuber development and biomass accumulation, contributing to higher final yields compared to our study. (Page 17, lines 598-601)

The discussion on page 16, lines 529-532, which addresses cooler temperatures, must be expanded to explicitly explain the study's application or consideration of both low (cooler) and high temperature extremes in the context of the crop model or analysis.
We appreciate this comment. This has been revised to clarify that while we acknowledge potential cold stress from low minimum temperatures, our analysis shows stress from the warming trend remains the dominant temperature constraint under future scenarios. This justifies our focus on heat-resistant adaptation strategies. We believe the revised text now explicitly addresses both temperature extremes and their relative importance. (Page 17, lines 614-617)

Study Limitations and Future Research:

This section should outline future research directions, such as advocating for longitudinal studies or investigating the heterogeneous climate change impacts across different agro-ecological zones of Shan State.

The limitations inherent in using a single study site and one crop variety must be critically discussed, comparing the approach to insights potentially gained from broader experimental trials and designs.

Thank you for the constructive suggestion. The section has been expanded to explicitly discuss the implications of using a single study site and a single potato cultivar and how these factors may limit the generalizability of the results. Additional recommendations for future research, such as broader experimental trials across different agro-ecological zones and testing multiple cultivars, have been added to strengthen the section and address potential uncertainties. (page 20, lines 763-764 and lines 777-789.

The authors must critically analyze the impact of post-Coup market fluctuations on agricultural practices, incorporating recent data and scholarly references. This analysis should specifically address how these economic factors may modulate the utilization of fertilizers and consequently influence crop yields.
We thank the reviewer for the constructive comment. We agree that post-coup market instability and input price fluctuations may influence farmers’ fertilizer use and thus crop yields. However, comprehensive and validated post-coup fertilizer price and usage data were not available for our study period. Incorporating such analysis would require assumptions beyond the scope of the current dataset. We have acknowledged this limitation in the revised manuscript and identified it as an important direction for future research when more reliable longitudinal data become available. (page 20, lines 795-798)

Section 5: Conclusions

The statement on lines 653-655 is overly general and lacks specificity. The authors must clearly articulate how the SUBSTOR model's simulation of potato growth specifically elucidates the effects of climate change and variability in the study region.
We thank the reviewer for this constructive feedback. We have revised the Conclusions section to provide greater specificity regarding the SUBSTOR-Potato model's findings. The revised text now explicitly states the model application, quantifies projected yield losses (25% under ssp585 by 2087), and identifies critical growth phases affected by climate change. The revised passage is on page 21, lines 833-839.

Given the described climate of the study region (cool winters, warm summers), the recommendation for developing heat-resistant varieties must be explicitly justified. The conclusion should clearly demonstrate why the projected temperature changes necessitate this specific, high-level adaptation strategy.
We appreciate the reviewer's request for clarification. Our analysis focuses specifically on the rainy season growing period, when temperatures are projected to increase by 29°C under the future climate. While the region experiences (cool winters, the warm summer), and average maximum temperature in the region during the rainy crop season (August to November) is 25.9°C. Potatoes in the future will face temperatures reaching >27°C, which will pose significant risks to tuber initiation and tuber bulking stages.

Current varieties are adapted to the baseline rainy season temperatures of 25.9°C. The projected warming, specifically during this critical growing period, justifies the development of heat-resistant varieties as a targeted adaptation strategy. We have clarified this seasonal focus and the magnitude of temperature change during the growing season in the revised conclusion on page 21, lines 845-851.

With regards,

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors,

I appreciate your submission and commend the relevance of your research assessing the impact of projected climate change on potato production in Southern Shan State, Myanmar. The integration of LARS-WG and the DSSAT–SUBSTOR-Potato model, along with analyses of planting date and SSP scenarios, offers valuable insights for future agricultural planning. The manuscript is scientifically sound; however, several points require clarification and minor revision to further strengthen the study.

The manuscript uses only ACCESS-ESM1-5 as the climate model. Since climate projections vary significantly across GCMs, relying on a single model may reduce robustness. Although this limitation is acknowledged, please provide a clear justification for selecting this particular GCM.
Validation results show very high nRMSE for summer crops (43.9% and 67.2%), indicating reduced model reliability under high-temperature conditions. Please discuss DSSAT’s known limitations under extreme heat and consider re-parameterizing TC and G3 for summer simulations.
The study uses default DSSAT silty-loam soil instead of site-specific field measurements. If actual soil data (texture, bulk density, WHC, SOC) were unavailable, please explicitly explain this limitation and discuss how it may affect simulation outcomes.
Kindly explain the rationale for incorporating a 3°C reduction in minimum temperature in your simulation setup.
The current simulations do not include the direct impact of elevated atmospheric CO₂ on potato photosynthesis and water-use efficiency. Since CO₂ fertilization can offset some heat-related yield losses, it is recommended to run simulations using CO₂ concentrations aligned with SSP scenarios (e.g., ~585 ppm for SSP585).
The manuscript notes increased late blight risk under high rainfall conditions (SSP585), yet disease impacts are not integrated into the yield simulations. As pests and diseases are highly climate-sensitive and critical to potato productivity, consider coupling DSSAT output with a late blight prediction model or discuss this as a limitation.
An incomplete sentence appears in this section (line 246-247). Please check.

Addressing these points will improve the overall quality of the manuscript.

With kind regards

Author Response

Is the research design appropriate? (Can be improved)
Thank you for your comment. We have re-examined our research design and believe it adequately addresses our research questions. If the reviewer has specific aspects that could be strengthened, we would welcome those suggestions and will gladly address them in our revision.

Are the methods adequately described? (Can be improved)
We thank the reviewer for this helpful feedback. In the revised manuscript, we have provided more detailed descriptions of our methods, including specifying the choice of GCM, the use of default soil data, and the details for the cost-benefit analysis for adopting fertilizer application strategy. These additions can be found on page 5, lines 180-183; page 7, lines 257-259; and page 15, lines 507-515. We believe these enhancements will allow readers to better understand and reproduce our methodology. We believe these enhancements will allow readers to better understand and reproduce our methodology. However, if the reviewer has identified particular methodological aspects that remain unclear or require a more comprehensive description, we would appreciate those specific comments and will address them promptly.

Are the results clearly presented? (Can be improved)
Thank you for the comment. We have revised the Results section for improved clarity and presentation, and we believe it is now improved.

Are the conclusions supported by the results? (Can be improved)
Thank you for the comment. We have revised the Conclusions section to improve clarity and alignment with the results, and we believe it is now stronger and better supported by our findings.

1. The manuscript uses only ACCESS-ESM1-5 as the climate model. Since climate projections vary significantly across GCMs, relying on a single model may reduce robustness. Although this limitation is acknowledged, please provide a clear justification for selecting this particular GCM.
We have clearly explained our choice for this particular ACCESS-ESM1-5 GCM based on the findings of Soe et al. (2024). According to their research, this GCM is one of the best models for reliably reproducing precipitation in Southeast Asia, as evaluated in the CMIP6 report (page 5, lines 180-183).

2. Validation results show very high nRMSE for summer crops (43.9% and 67.2%), indicating reduced model reliability under high-temperature conditions. Please discuss DSSAT’s known limitations under extreme heat and consider re-parameterizing TC and G3 for summer simulations.
We thank the reviewer for this valuable suggestion. Following this recommendation, we conducted sensitivity analyses for both TC and G3 parameters to improve model performance under high-temperature summer conditions. To address high nRMSE for the summer season (irrigated crop), we perform sensitivity analyses on TC and G3. For TC optimization, values were systematically varied from 14°C to 44°C in 1.5°C increments (20 iterations), while maintaining the original G3 value (22.62). Simulated yields were compared against observed data for both summer production years, and the TC value minimizing root mean square error was identified. For G3 sensitivity analysis, values were tested from 22.62 to 62.62 (20–40 iterations) to assess whether growth rate adjustments could further improve model performance. Both individual TC optimization and combined TC+G3 adjustments (constrained to the realistic G3 range of 21–26) were evaluated.
Results show that nRMSE is very high under rainfed conditions. Please refer to the table below for details. While the optimized parameters (TC = 15.5°C) substantially improved performance for irrigated summer crops (nRMSE reduced from 43.9–67.2% to <5%), rainfed crops during the rainy season showed persistently high nRMSE values even after optimization. These contrasting results suggest that irrigated and rainfed production systems require distinct parameter sets to adequately capture yield variability.
However, given that rainfed production is the primary focus of our study and represents the dominant production system in our study region, we have retained the original parameter set for rainfed simulations. This decision ensures that our climate change projections reflect the behavior of the model under conditions most representative of current agricultural practices. The optimized TC parameter (15.5°C) was applied only to summer irrigated scenarios, where model performance was critically inadequate with the original parameters.

Table. Evaluation of yields across different seasons using optimized parameters

Cropping Season	Observed Yield (t/ha)	TC 15.5°C + G3 22.62			TC 15.5°C + G3 26
Cropping Season	Observed Yield (t/ha)	Simulated Yield (t/ha)	RMSE	nRMSE	Simulated Yield (t/ha)	RMSE	nRMSE
2015 (Rainfed)
Ridging trial	22.7	37.6	14.9	65.0%	42.9	20.2	88.9%
N application trial	19.9	37.6	17.7	88.9%	42.9	23	115.5%
K application trial	25.3	37.6	12.3	48.6%	42.9	17.6	69.5%
2021 (Rainfed)	18	43.9	25.9	143.8%	50.5	32.5	180.5%
2022 (Rainfed)	22.1	52.3	30.2	136.6%	60.1	38	171.9%
2023 (Summer-Irrigated)	25	26.1	1.1	4.4%	29.7	4.7	18.8%
2024 (Summer-Irrigated)	18.9	18.9	0	0.0%	21.8	2.9	15.3%

3. The study uses default DSSAT silty-loam soil instead of site-specific field measurements. If actual soil data (texture, bulk density, WHC, SOC) were unavailable, please explicitly explain this limitation and discuss how it may affect simulation outcomes.

Thank you for highlighting this critical point.

We have revised our manuscript regarding our use of default soil information in DSSAT. This use was based on a previous study by Pronk et al. (2016), which states that Naungtayar belongs to the silty-loam soil type. The revised passage is on page 7, lines 257-259.

In our revision, we have discussed the potential impact of using default parameters on simulation outcomes, as these parameters do not consider local variations in soil hydraulic properties and organic matter content. Additionally, we have provided recommendations for future research. (Page 20, lines 763-768)

4. Kindly explain the rationale for incorporating a 3°C reduction in minimum temperature in your simulation setup.

We thank the reviewer for this critical question.

The 3°C reduction in minimum temperature was applied because the model consistently failed to simulate realistic tuber yields with the original climate data. While the model accurately reproduced most crop growth variables, it resulted in “0” tuber yields, indicating that the minimum temperatures in the dataset were higher than those experienced by the crop in the field. Since potato tuber initiation is sensitive to nighttime temperatures, this adjustment (-3°C) was necessary to align simulations with observed conditions.

5. The current simulations do not include the direct impact of elevated atmospheric CO₂ on potato photosynthesis and water-use efficiency. Since CO₂ fertilization can offset some heat-related yield losses, it is recommended to run simulations using CO₂ concentrations aligned with SSP scenarios (e.g., ~585 ppm for SSP585).

We run simulations to examine the impact of atmospheric CO₂ on potato production using CO₂ concentrations aligned with ssp scenarios: 460 ppm for ssp126, 550 ppm for ssp245, and 790 ppm for ssp585, as detailed by Kim et al. (2024). The integration of CO₂ fertilizations is likely to mitigate the negative impacts on potato tuber yield. We have included our simulation results in Section 3.5.5 and the description of these findings in our revised manuscript on page 15, lines 523-532 and figures in supplementary files S1 and S2. We also discussed our results on page 19, lines 715-723. And we have removed the discussion for the limitation of our study, mentioning excluding CO₂ effects on page 20, in Section 4.5.

6. The manuscript notes increased late blight risk under high rainfall conditions (SSP585), yet disease impacts are not integrated into the yield simulations. As pests and diseases are highly climate-sensitive and critical to potato productivity, consider coupling DSSAT output with a late blight prediction model or discuss this as a limitation.

We revised this statement in the revised manuscript, explaining that the study did not account for disease dynamics in yield simulations and including a discussion for future research direction. (Page 17, lines 607-611)

7. An incomplete sentence appears in this section (line 246-247). Please check.

Thank you for the observation. The incomplete sentence has been corrected in the revised manuscript.