Review Reports - Moderate Deficit Irrigation and Reduced Nitrogen Application Maintain Tuber Quality and Improve Nitrogen Use Efficiency of Potato (<i>Solanum tuberosum</i> L.)

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors conducted a two-year (2016-2017) field experiment with three irrigation levels and two nitrogen application rates, using four commercial potato cultivars grown in the San Luis Valley, as research subjects. The study aimed to investigate the effects of deficit irrigation and reduced N application on potato tuber quality, water use efficiency, and nitrogen use efficiency. The research design is reasonable with relatively sufficient data support, providing a scientific basis for water- and fertilizer-saving potato cultivation in arid and water-scarce regions. However, there is a critical question to be addressed: in Introduction, the authors mention that the watershed is experiencing water shortages at the present time (2025). Given this, why did the authors choose data from 2016 to 2017 to address the current water shortage issue? And is this choice of historical data sufficiently persuasive for solving the existing problem? More detailed issues are listed as following, please answer the questions one-by-one.

1, In Results, 3.1. Climate, the authors only enumerated one climatic factor (precipitation) and did not mention other climatic factors, such as temperature and sunlight. Therefore, it is necessary to question whether the title “Climate” needs to be revised to a more specific term like “precipitation” to accurately reflect the scope of climatic factors discussed in the study.

2, The paper selected four potato cultivars with non-significant differences. For example, the maturity periods ranged from early to medium, and the specific gravity was from medium to high), but it did not provide sufficient explanations for the differential performances of their quality traits in both the Results and Discussion sections. In the Discussion section, although the authors mentioned that tuber quality differs depending on cultivar, particularly in their response to water stress and attributed annual differences in quality traits to the “yield dilution effect”, they failed to link these general statements to the specific differential performances of the four cultivars. For example, there was no explanation for why Mesa Russet had strong stability in quality traits across treatments, while Yukon Gold was sensitive to N levels in 2016. No discussions were conducted on whether cultivar-specific genetic characteristics or physiological mechanisms contributed to the observed differences in quality traits. Overall, the paper merely describes the phenotypic differences in quality traits among cultivars but lacks in-depth exploration of the underlying reasons, resulting in an insufficient explanation of cultivar-specific variations in quality traits.

3, In addition, there are numerous formatting issues in terms of details throughout the whole manuscript. For example, the full name of the abbreviation “IRRG3” was not explained when it first appeared in the main text; in Line 177, the full name of the abbreviation “SC” was incomplete; in the “2.1 Experimental Site” section, the superscripts and subscripts of units were not formatted correctly; and the entire text was not justified (aligned at both left and right margins). It is recommended that the authors carefully review and revise the entire manuscript to ensure it meets the publication requirements.

Author Response

Response: The water shortage has been going on for more than 20 years and is likely to continue to get worse due to climate change. We have added a sentence to clarify this (lines 48-49).

Comment 1: In Results, 3.1. Climate, the authors only enumerated one climatic factor (precipitation) and did not mention other climatic factors, such as temperature and sunlight. Therefore, it is necessary to question whether the title “Climate” needs to be revised to a more specific term like “precipitation” to accurately reflect the scope of climatic factors discussed in the study.

Response 1: We have changed the title of section 3.1 to Precipitation, as requested.

Comment 2. The paper selected four potato cultivars with non-significant differences. For example, the maturity periods ranged from early to medium, and the specific gravity was from medium to high), but it did not provide sufficient explanations for the differential performances of their quality traits in both the Results and Discussion sections. In the Discussion section, although the authors mentioned that tuber quality differs depending on cultivar, particularly in their response to water stress and attributed annual differences in quality traits to the “yield dilution effect”, they failed to link these general statements to the specific differential performances of the four cultivars. For example, there was no explanation for why Mesa Russet had strong stability in quality traits across treatments, while Yukon Gold was sensitive to N levels in 2016. No discussions were conducted on whether cultivar-specific genetic characteristics or physiological mechanisms contributed to the observed differences in quality traits. Overall, the paper merely describes the phenotypic differences in quality traits among cultivars but lacks in-depth exploration of the underlying reasons, resulting in an insufficient explanation of cultivar-specific variations in quality traits.

Response 2: Thank you for the comment. We agree that the four cultivars were broadly similar (early–medium maturity; medium–high SG classes). This is in part due to their suitability to the arid, high elevation environment in the San Luis Valley. The cultivars selected, even though they may be similar in terms of maturity class, are very different in their agronomic performance. For example, while Russet Norkotah3 has early field emergence, Canela Russet is a very late emerging cultivar, which could influence the photosynthetic capacity of the two cultivars. It is, therefore, not surprising that differences were observed in their quality traits. Genotypic differences in canopy duration, carbohydrate partitioning, and stress tolerance, all of them with environmental and management interactions, can still produce differential quality outcomes even among ostensibly similar classes [29,33].

However, these experiments were not designed to compare cultivars, having been laid out as four separate experiments (lines 122-123 and 132-133). The cultivars were evaluated independently for their response to deficit irrigation and N input; therefore, we did not attempt to discuss quality differences among cultivars.

Comment 3. In addition, there are numerous formatting issues in terms of details throughout the whole manuscript. For example, the full name of the abbreviation “IRRG3” was not explained when it first appeared in the main text; in Line 177, the full name of the abbreviation “SC” was incomplete; in the “2.1 Experimental Site” section, the superscripts and subscripts of units were not formatted correctly; and the entire text was not justified (aligned at both left and right margins). It is recommended that the authors carefully review and revise the entire manuscript to ensure it meets the publication requirements.

Response 3: We have defined IRRG3 in line 234. The SC abbreviation in line 189 has been corrected, so it is now complete, we have fixed the formatting in section 2.1, and we have justified the text throughout the document, as well. Thank you for pointing these errors out.

Reviewer 2 Report

Comments and Suggestions for Authors

This study investigated the effect of deficit irrigation and reduced N application on tuber quality parameters of potato. It is of importance for enhancing water use efficiency, minimizing nitrogen leaching, and maintaining high-quality potato production to support sustainable agriculture. Similar topics have been previously reported. The novelty of the manuscript was lacked. There are some issues need to be addressed. The specific comments are as following:

In section 2.1, the unit of latitude and longitude was not correct.
In section 2.1, lots of important soil physiochemical properties were lacked, such as soil NH₄⁺-N content, available P and K content, bulk density, CEC, organic matter, etc.
How were soil moisture dynamics monitored? This information should be provided.
In Table 2, what does treatment “In season” mean? when was the fertilizers applied? This detail needs to be clarified.
In Table 2, how was recommended nitrogen application rate obtained?
From Table 3 to 10, the mean value should be followed by standard deviation or standard error to improve the statistical clarity and reproducibility of the data. In addition, the unit of all traits in the tables need to be added.
In section 2.3.4, in these two equations, what does SG mean?
Yield is a critical final indicator of crop productivity. The yield of potato needs to be analyzed.
In the conclusion section, "Reducing N application (131 kg N ha⁻¹) …… without negatively impacting yield", how can you get this conclusion since the yield data was not presented in the results section.
The whole language of the manuscript need to be polished by native English speaker.

Author Response

Response: This manuscript is novel with respect to the cultivars evaluated. Previous reports on this topic involved different potato cultivars in different climatic environments. Moreover, potato cultivars can be unique in their requirements for agronomic inputs, which can influence their quality potential.

The specific comments are as following:

In section 2.1, the unit of latitude and longitude was not correct.

Response 1: This has been corrected (line 112).

2. In section 2.1, lots of important soil physiochemical properties were lacked, such as soil NH₄⁺-N content, available P and K content, bulk density, CEC, organic matter, etc.

Response 2: We have added a new table (Table 1) to elucidate the soil properties in greater detail as requested.

3. How were soil moisture dynamics monitored? This information should be provided.

Response 3: Soil moisture dynamics were not monitored in this study.

4. In Table 2, what does treatment “In season” mean? when was the fertilizers applied? This detail needs to be clarified.

Response 4: In-season means during the growing season, not prior to planting. “After tuberization, in-season N fertilizer was applied in three split applications at weekly intervals, with the first in-season N application at 64 and 50 days after planting (DAP) in 2016 and 2017, respectively.” This statement is found in lines 156-159. The table has changed numbers to Table 3.

5. In Table 2, how was recommended nitrogen application rate obtained?

Response 5: A sentence describing the basis for the N recommendation has been added in lines 159-161 including a citation.

6. From Table 3 to 10, the mean value should be followed by standard deviation or standard error to improve the statistical clarity and reproducibility of the data. In addition, the unit of all traits in the tables need to be added.

Response 6: Standard errors have been added to Tables 4-11 (table numbers changed due to the addition of a new table). SG has no units, and units have been added for all other variables.

7. In section 2.3.4, in these two equations, what does SG mean?

Response 7: The abbreviation was defined in line 74, the first time it was used.

8. Yield is a critical final indicator of crop productivity. The yield of potato needs to be analyzed.

Response 8: Yield results were analyzed and evaluated in a previously published paper which is cited in this work: [7] Barka, A.M.H.; Essah, S.Y.C.; Davis, J.G. Deficit irrigation and nitrogen application rate influence growth and yield of four potato cultivars (Solanum tuberosum L.). Horticulturae 2025, 11, 849. https://doi.org/10.3390/horticulturae11070849

In addition, the relationship between yield from these plots with potato quality and resource use efficiencies is discussed in sections 4.3 and 4.5.

9. In the conclusion section, "Reducing N application (131 kg N ha⁻¹) …… without negatively impacting yield", how can you get this conclusion since the yield data was not presented in the results section.

Response 9: We have added a citation (7. Barka et al., 2025) to support the yield results (lines 443-444). The yield data has been previously published in this paper and, therefore, should not be repeated in a second paper.

10. The whole language of the manuscript need to be polished by native English speaker.

Response 10: The corresponding author is a native English speaker. She has carefully polished the entire manuscript, as requested.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The raised comments in the manuscript have been addressed. The current manuscript can be accepted for publication.