Differential Physiological Responses to Different Drought Durations among a Diverse Set of Sugarcane Genotypes

Round 1

Reviewer 1 Report

The present study explores the physiological responses of sugarcane genotypes to drought conditions. The current work is both clear and intriguing. I have a few points that require further attention for improvement:

1. How do the authors measure the frequency of drought?
2. The authors mentioned that water withholding occurred for a period of 3-6 months. Why was an exact duration not specified?
3. The authors should provide details regarding the process of collecting MAT (Mean Annual Temperature) data.
4. The figures in the manuscript need improvement. The font size of the figure text is too small, especially in figures 3-5.
5. The statistical analysis should undergo a thorough reevaluation.
6. I am uncertain about the authors' rationale for using red color in tables 1 and 2.
7. Please update the list of references to include more recent sources.

 

Author Response

Reviewer-1

Manuscript ID:  agronomy- 2620231

Title: Differential physiological responses to varying drought durations among a diverse set of sugarcane genotypes

 

We appreciate your valuable suggestions for further improving the manuscript, and we agree with almost all comments and suggestions from reviewers. Therefore, the manuscript has been revised as your suggestions. Any revisions made can be seen through track-change mode and are highlighted in yellow. The details of the revision are given below.

 

Comments on the Quality of English Language: I am not qualified to assess the quality of English in this paper.

Response English Language: We thank the reviewer for pointing out this issue. The quality of English language has been improved by proofreading the whole manuscript carefully. Significant improvements have been made related to grammatical errors, articles, spacing, and word choices, especially in material and method. Any revisions are highlighted in yellow.

 

Point 1: How do the authors measure the frequency of drought?

Response 1: We thank the reviewer for pointing out this issue. The soil moisture content of each sub-plot (total 72 sub-plot) was measured monthly using gravimetric method to determine the drought stress (in Lines 209-211 of corrected manuscript). We further address the soil moisture content of previous research that had an effect on sugarcane physiological traits ( ¼ available water (AW) Leanasawat et al.[8], 2021; Khonghintaisong et al., 2021 [12], and we mentioned the available water level of our water treatments (as can be seen in Lines 222-225). As a result, the sugarcane in this study was grown under water deficit conditions, which caused the crop to face a short and long drought period following the water treatments as shown in Figure 1c, e plant cane and d, f (ratoon cane). Figure 1 shows the soil moisture content for the SD2 treatment beginning to decline in December while that for the SD1 (short drought) did not begin to decline till February. That for the SD0 was sustained throughout the year.

 

Point 2: The authors mentioned that water withholding occurred for a period of 3-6 months. Why was the exact duration not specified?

Response 2: We appreciate this valuable suggestion; thus, we added the exact duration of water withholding in the material and method part (as can be seen in Lines 120-127).

“For the short–term drought treatment (SD1) (3 months water withholding duration), water was withheld from the 3^rd – 6^th MAT (plant cane) and 3^rd – 6^th MAH (ratoon cane). These occurred between 17 February 2021 to 16 May 2021 in the plant cane and between 17 February 2022 to 16 May 2022 in the ratoon cane. For the long–term drought treatment (SD2) (5 months water withholding duration) water was withheld from the 1^st – 6^th MAT/MAH. These occurred between 17 December 2020 to 16 May 2021 in the plant cane and from 17 December 2021 to 16 May 2022 in the ratoon cane.”

 

Point 3: The authors should provide details regarding the process of collecting MAT (Mean Annual Temperature) data.

Response 3: We apologized for making you misunderstand this: In our study, the term "MAT" refers to the months after transplanting, not to the mean annual temperature. In this study, we provide daily temperature data for both the minimum and maximum values (can be seen in Lines 189-190 and 193-194).

 

Point 4: The figures in the manuscript need improvement. The font size of the figure text is too small, especially in figures 3-5.

Response 4: We thank the reviewer for pointing out this issue. Figures 1, 3, 4, 5, and 6 were improved to 16 Palatino Linotype font size instead of the previous 12 size. The updated Figures 1, 3, 4, 5, and 6 can be seen in the revised manuscript. Figure 1 can be seen in Lines 230, Figure 3 can be seen in Lines 330, Figure 4 can be seen in Lines 376,377, while Figure 5 can be seen in Lines 394, and Figure 6 can be seen in Lines 517.

 

Point 5: The statistical analysis should undergo a thorough reevaluation.

Response 5: We thank you for this insightful feedback. The statistical analysis was checked again and reevaluated. It was also rewritten for clarity. We found eight sub-graphs the (figure 3a, 4a, 4b, 4c, 4d, 4e, 6a, and 6b) receiving errors: Figure 3a in SD2 at 4 MAT change from non-significant to significant (revised text result line 323-326,Figure at Lines 330). Figure 4a KK3 in SD0 at 1 MAT change from bc to b and UT12 change from bc to b, at 5 MAT, KK09-0939 and TPJ04-768 change from c to b. Figure 4b in SD0 at 3 MAT, KK09-0358 change from c to d and KK09-0939 change from d to e, at 4 MAT, F03-362 change from ab to a and UT12 change from ab to a, in SD1 at 4 MAT, F03-362 and KK09-0358 change from b to c, KK09-0939 change from ab to bc and KK3 change from a to ab. Figure 4c in SD2 at 1 MAT change from non-significant to significant. Figure 4d, in SD0 at 1 MAH, TPJ04-768 change from b to c and 3 MAH, KK09-0358 change from b to bc, KK09-0939 change from b to c, TPJ04-768 change from c to d, in SD1 at 3 MAH, F03-362 change from ab to bc, KK09-0358 and KK09-0939 change from cd bc and TPJ04-768 change from c cd. Figure 4e in SD0 at 6 MAH, KK09-0358 change from b to bc and KK09-0939 change from b to c, in SD1 at 6 MAH, F03-362 and KK09-0358 change from ab to b, KK09-0939 change from bc to c, TPJ04-768 change from d to e and KK3 change from cd to d, in SD2 at 6 MAH change from non-significant to significant. Figure 6a and 6b all three treatments some the statistical letter change, for fig. 6a at 6 MAT in all three treatments some the letter changes and at 3 MAT some the letter change. The change in the statistical letter in graphs did not come from the change in value of the result, and the order of the result did not change too. Therefore, the results in these cases in the text remained unchanged. We apologize for this error.

 

Point 6: I am uncertain about the authors' rationale for using red color in tables 1 and 2.

Response 6: We expressed our regret for this error. To make it simpler to understand when writing the manuscript, we made the color red. However, this red color was eliminated from the revised version.

 

Point 7: Please update the list of references to include more recent sources.

Response 7: We appreciate the reviewer bringing this to our attention. The reference has been updated with more current sources and removed not updated and the self-citation references. The corrected manuscript includes the updated references list (Lines 640-777).

The reference removes:

Santos, R.F.; Carlesso, R. Water deficit and morphologic and physiologic behavior of the plants. Bras. de Eng. Agric. Ambient. 1998, 2, 287–294.

Singh, S.; Rao, P.N.G. Varietal differences in growth characteristics in sugarcane. Agric. Sci. 1987, 108, 245–247. (https://doi.org/10.1017/S0021859600064327)

Jangpromma, N.; Songsti, P.; Thammasirirak, S.; Jaisil, P. Rapid assessment of chlorophyll content in sugarcane using a SPAD chlorophyll meter across different water stress conditions. Asian J. Plant Sci. 2010, 9, 368–374. (https://doi.org/10.3923/ajps.2010.368.374)

Mehlich, A. Mehlich 3 soil test extractant: a modification of Mehlich 2 extractant. Soil Sci. Plant Anal. 1984, 15, 1409–1416. (https://doi.org/10.1080/00103628409367568)

Doorenbos, J.; Pruiit, W.O. Calculation of crop water requirements; Food and Agriculture Organization of the United Nations: Rome, Italy, 1992. (https://doi.org/10.1061/(ASCE)0733-9437(1991)117:5(758)

Doorenbos, J.; Kassam, A.H. Yield Response to Water; FAO Irrigation and Drainage Paper No. 33. FAO: Rome, Italy, 1979.

Irvine, J.E. Sugarcane [physiological characteristics, yield potential and climatic and environment factors]. In Symposium on Potential Productivity of Field Crops Under Different Environments, Los Banos, Laguna (Philippines), 1983; International Rice Research Institute: Los Banos, Laguna (Philippines), 1983, 361-381.

Jones, M.B.; Muthuri F.M. The diurnal course of plant water potential, stomatal conductance and transpiration in a papyrus (Cyperus papyrus) canopy. Oecologia 1984, 63, 252–255.

Silva, M.A.; Jifon, J.L.; Da Silva, J.A.G.; Sharma, V. Use of physiological parameters as fast tools to screen for drought tolerance in sugarcane. J. Plant Physiol. 2007, 19, 193–201. (https://doi.org/10.1590/S1677-04202007000300003)

Silva, M.A.; Jifon, J.L.; da Silva, J.A.G.; dos Santos, C.M.; Shama, V. Relationships between physiological traits and productivity of sugarcane in response to water deficit. Agric. Sci. 2014, 152, 104–118. (https://doi.org/10.1017/S0021859612000834)

Sheen, J. Feedback control of gene expression. Res. 1994, 39, 427–438.

Stitt, M.; Krapp, A. The interaction between elevated carbon dioxide and nitrogen nutrition: the physiological and molecular background. Plant Cell Environ. 1999, 22, 583–621. (https://doi.org/10.1046/j.1365-3040.1999.00386.x)

 

The added reference updates:

Pipitpukdee, S.; Attavanich, W.; Bejranonda, S. Climate change impacts on sugarcane production in Thailand. Atmosphere 2020, 11(4), 408. (https://doi.org/10.3390/atmos11040408)

Devi, K.; Gomathi, R.; Arun Kumar, R.; Manimekalai, R.; Selvi, A. Field tolerance and recovery potential of sugarcane varieties subjected to drought. Indian Journal of Plant Physiology 2018, 23, 271-282. (https://doi.org/10.1007/s40502-018-0367-7)

Dinh, H. T.; Watanable, K.; Takaragawa, H.; Kawamitsu, Y. Effects of drought stress at early growth stage on response of sugarcane to different nitrogen application. Sugar Tech 2018, 20, 420-430. (https://doi.org/10.1007/s12355-017-00566-y)

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear editor and authors,

In this study, 3 water treatments and 6 different genotypes of sugarcane were used to investigate the physiological characteristics of sugarcane in response to drought stress. The experimental design is reasonable, the workload is more, and the character investigation is more comprehensive. The results provided a scientific basis for drought-resistant breeding and cultivation optimization of sugarcane. However, the manuscript still has the following problems that need further improvement:

1.    The main purpose of the study is unclear and the results need to be refined further. What are the different physiological responses of different genotypes of sugarcane to drought stress? From the abstract and the expression of the article can not be reflected. The author needs to elaborate further.

2.    The topic of the paper is drought stress, but in the materials and methods, the author does not specify the threshold of drought stress, but only describes the different irrigation water treatment under natural precipitation conditions. Do these treatments meet the threshold of drought stress? If not drought stress, the title of this paper should be changed to physiological effects of different water treatments on different genotypes of sugarcane.

3.    In this experiment, six different genotypic varieties or strains were selected. However, the genetic background of F03-362, KK09-0358, TPJ04-768 and KK09-0939 is not clear, and they are only hybrid progeny materials, and their genetic characteristics are unstable. KK3 is defined as a medium drought resistant variety and UT12 is defined as a drought sensitive variety. What is the scientific basis for this?

4.    In results, the growing conditions should be moved to the should be moved to the Materials and Methods.

5.    The difference significance analysis between different treatments needs to be corrected. For example, as shown in Figure 3, the difference between processes in 3MAT is not significant, but it is significant in 4MAT with smaller differences. Similar phenomena also appear in other figures.

6.    In addition, in order to more accurately reflect the physiological response of different genotypes to different water treatments, the difference value between water deficiency treatment and normal water supply treatment is better.

I think the English level of this manuscript is good, but the expression of sentences is not clear enough, and the quality needs to be further improved.

Author Response

Reviewer-2

Manuscript ID:  agronomy- 2620231

Title: Differential physiological responses to varying drought durations among a diverse set of sugarcane genotypes

 

We appreciate your valuable suggestions for further improving the manuscript, and we agree with almost all comments and suggestions from reviewers. Therefore, the manuscript has been revised as your suggestions. Any revisions made can be seen through track-change mode and are highlighted in yellow. The details of the revision are given below.

 

Comments on the Quality of English Language: Moderate editing of English language required (I think the English level of this manuscript is good, but the expression of sentences is not clear enough, and the quality needs to be further improved.)

Response English Language: We thank the reviewer for pointing out this issue. The quality of English language has been improved by proofreading the whole manuscript carefully. Significant improvements have been made related to clarifying sentences , especially in material and method. Any revisions are highlighted in yellow.

 

Point 1: The main purpose of the study is unclear and the results need to be refined further. What are the different physiological responses of different genotypes of sugarcane to drought stress? From the abstract and the expression of the article can not be reflected. The author needs to elaborate further.

Response 1: We appreciate this valuable comment. We improve the result in accordance with the main purpose, and we refined the result in term of the different physiological responses of different genotypes of sugarcane to drought stress (as can be seen in Lines 323-329, 350-375, 387-393, 406-411, 435-438, and 449-455).

This result is further addressed in the abstract (Lines 20-35)

            “F03-362 (F₁), KK09-0358 (BC₁), and KK3 (cultivar) demonstrated greater tolerance to drought by maintaining comparatively higher photosynthetic activity, while KK09-0939 (BC₂) and TPJ04-768 (BC₁) were more sensitive. KK3 and UT12 (cultivar) consistently maintained comparatively higher levels of photosynthesis under drought in the ratoon crop, although stomatal conductance values were comparable to those of other genotypes. Drought significantly reduced dry matter in all genotypes, but more so in the two cultivars.”

Further addressed conclusion sections (Lines 601-609):

“Three genotypes, namely, F03–362(F₁), KK09-0358 (BC₁), and KK3 displayed superior tolerance to soil moisture deficit exposure and were able to sustain higher photosynthetic activity during and after the drought recovery period. Two genotypes KK09–0939(BC₂) and TPJ04–768 (BC₁) were more sensitive to drought exposure, especially under the SD2, plant cane crop cycle. During the ratoon crop cycle two genotypes, KK3 and UT12 consistently had some of the highest A values during drought exposure, even though their gs values were similar to those of other genotypes. Such genotypic differences in the ability to tolerate drought episodes and still sustain economic yield levels are important in crop improvement for rainfed production systems where resource availability is unpredictable.”

 

Point 2: The topic of the paper is drought stress, but in the materials and methods, the author does not specify the threshold of drought stress, but only describes the different irrigation water treatment under natural precipitation conditions. Do these treatments meet the threshold of drought stress? If not drought stress, the title of this paper should be changed to physiological effects of different water treatments on different genotypes of sugarcane.

Response 2: We thank the reviewer for pointing out this issue. We further address the soil moisture content of previous research that had an effect on sugarcane physiological traits (1/4 available water (AW) Leanasawat et al., 2021 [8]; Khonghintaisong et al., 2021 [12], and we mentioned the available water level of our water treatments (as can be seen in Lines 223-226). In addition, in resistant sugarcane cultivars, there obtain RWC value that represents water status in leaf range 85-87% (Silva et. al. 2013 [18]). Similar to our study's finding that 83–94% of subjects encountered long water withholding treatment. As a result, the sugarcane in this study was grown under drought stress by water withholding water at some of the plots as depicted in Figure 1. The figure 1 shows the soil moisture content for the SD2 treatment beginning to decline in December while that for the SD1 (short-term drought) did not begin to decline till February. That soil moisture content in the SD0 treatment, the no drought stress treatment, was sustained throughout the year.

However, we absolutely agreed with the reviewer, that the title was changed to " Differential physiological responses to different water withholding durations (from its initial varying drought durations) among a diverse set of sugarcane genotypes " following the suggestion from reviewer.

 

Point 3: In this experiment, six different genotypic varieties or strains were selected. However, the genetic background of F03-362, KK09-0358, TPJ04-768 and KK09-0939 is not clear, and they are only hybrid progeny materials, and their genetic characteristics are unstable. KK3 is defined as a medium drought resistant variety and UT12 is defined as a drought sensitive variety. What is the scientific basis for this?

Response 3: We thank the reviewer for pointing out this issue. The objective of the study was to understand the physiological responses of different durations of drought on sugarcane. We simulated several environments including no drought, short-term, and long-term drought including two crops. To accomplish this objective, we needed to include a set of genotypes from diverse backgrounds. Therefore, we sampled a diverse set of genotypes ranging from cultivars to F₁ to BC₁s and BC₂ and with different characteristics with regards to yield parameters and previous history from a related study.

The sugarcane used in this study is an advanced clone that is selected from the hybrid population. Absolutely, sugarcane, which has a high chromosomal number of 2n=100 to 130 in different cultivars and is exceedingly complex, has been discovered to have high polyploidy and heterozygosity. However, hybrid progeny sugarcanes directly propagate from the stalk without further fertilization. The genetic characteristics of these progeny are determined in this stage.

However, in order to clarify this point. We addressed the pedigree of each investigated hybrid progeny material (as can be shown in Lines 142-148). We also mention further the scientific basis for the categories of commercial cane, such as KK3 and UT12 (as seen in Lines 138-140).

 

Point 4: In results, the growing conditions should be moved to the should be moved to the Materials and Methods.

Response 4: We appreciate the reviewer bringing this to our attention. We moved this section to the “Materials and Methods” part. (Line 186-198 and 217-235)

 

Point 5: The difference significance analysis between different treatments needs to be corrected. For example, as shown in Figure 3, the difference between processes in 3MAT is not significant, but it is significant in 4MAT with smaller differences. Similar phenomena also appear in other figures.

Response 5: We thank you for this insightful feedback. Even though we fix the sampling plant (use the same plant for all collection dates) and collected the leaf position at the 2^nd expanded leaf of main stem, the leaf sampling changed with different collection date following the age of sugarcane. This can cause different variations in each collection date. Therefore, the error variance for statistical testing may be different from time to time of data collection.

In addition: The statistical analysis was checked again. We found eight graphs (3a, 3b, 4a, 4b, 4c, 4d, 4e, 6a, and 6b) receiving errors: 1) Importing the incorrect value into the graph. 2) On figure 3b, 4a, 4b, 4c, 4d, 4e, 6a, and 6b, the statistical sign was incorrect; therefore, we were corrected statistical letters in figure 3b, 4a, 4b, 4c, 4d, 4e of SD0, SD1, and SD2., and figure 6a and 6b of SD0, SD1, and SD2. We apologized for this error.

 

Point 6: In addition, in order to more accurately reflect the physiological response of different genotypes to different water treatments, the difference value between water deficiency treatment and normal water supply treatment is better.

Response 6: We thank the reviewer for pointing out this issue. We improved the result as accurately reflecting the physiological response of different genotypes to different water treatments (between SD0 and SD1, SD0 and SD2) (as can be found at Lines 323-329, 350-375, 387-393, 406-411, 435-438, and 449-455).

Author Response File: Author Response.pdf

Reviewer 3 Report

By investigating how several genotypes of sugar cane respond to changes in water availablity throughout the growing season, this paper addresses the possibillity of how growers may mitigate the impacts of future climate change on crop yields of this commodity.  It is therefore a timely piece of research and I commend the authors for identifying it as a pressing issue that is worthy of their research focus.

The answers to the question of specifically what plant physiological aspects are affected by periodic drought is most interesting, since it may be possible to extend this kind of approach to other croped species and their various cultivars.  The finding that carefully applied irrigation, to maximise use of what may become in the future a much scarcer resource, is especially interesting since it may also be a topic for investigation of other cropped species that currently rely on irrigation for maximising yields.

I therefore recommend this paper may be published without any further significant changes.

Author Response

We appreciate your kind evaluation very much.