Relationship between Phosphorus and Nitrogen Concentrations of Flax

Round 1

Reviewer 1 Report

Please see attachment file.

Comments for author File: Comments.pdf

Author Response

Dear referee,

RE: Manuscript ID: agronomy-2216018.

We thank editor and two referees very much for offering some excellent, constructive suggestions for further improvement the manuscript. Accordingly, we have revised the manuscript carefully by following all the comments and suggestions. All those detailed, changes have been followed. We trust that all issues/concerns raised by two referees have been adequately addressed and the manuscript is acceptable for publication in Agronomy.

Below are our responses, point-by-point, to each of the suggestions.

 

Reviewer 1

The authors studied the relationship between the increase in soil P fertility and the P and N content in flax to build the model for critical P concentration in this plant, as a function of N concentration in shoot of flax for diagnostic purposes. Study concerns different cultivars, five doses of P in different locations and years, but limited information on soil and overall plant nutritional status are presented. In my opinion, the study was not fully well planned. Recognizing all aspects related to increasing the nutrient use efficiency (especially N) from all sources is crucial in terms of crop quality, environmental impact and costs but the analysis should be more comprehensive. Questions arise when reading the manuscript:

1. Is the analysis of only two components in the plant material sufficient to assess these relationships? Plants need 14 essential elements and many interactions between them affect the uptake of a given one. Authors write themselves “According to the ‘Liebig law of the minimum’, growing plants require essential elements in certain proportions”. Based on the presented results, we know very little about it. Of course, the point is not to carry out a complete set of analyzes in each of the examined objects, but data, even in the restricted range, would be valuable.

Answer: Thank you very much for offering precious suggestions, we only explored the two components of relationship between nitrogen and phosphorus in the plant materials in the current study. According to your excellent suggestions and combined the other referee¢ advices, we amended the content “According to the ‘Liebig law of the minimum’, growing plants require essential elements in certain proportions; if actual proportions differ from ideal ones, growth is limited and the element is relatively scarcest [48]. Further, Güsewell [18] elaborated that the ‘law of the minimum’ means that N and P concentrations are suboptimal, there is a ‘critical N:P ratio’ below which growth is limited only by N and above which growth is limited only by P. ” to “According to the opinion of Güsewell [14] that there is a ‘critical N:P ratio’ below which growth is limited only by N and above which growth is limited only by P. ”   

2. On what basis were the doses of phosphorus determined - they seem to be very high, especially the last two, but also 80 kg P₂O₅. Especially as authors state “Lower biomass in our study (ranged from 1 to 7 t ha⁻¹) compared to those conducted in northern France (1 to 10 t ha⁻¹) could be correlated with differences in water availability .. and growing seasons duration (i.e.>150 days in 2006 the study)”.

Answer: Thanks! The doses of phosphorus were basis on “The soil contains 8.0 and 8.7 mg kg^-1 of available P in 2018 and 2019, respectively. -------When P concentration is below 10 mg kg^–1 (Ozturk et al., 2005). ”

After careful consideration basis on your valuable suggestions, combined with the opinions from the other referee, we changed the sentence “The growing season in Gansu, China, is cold and dry conditions and a short growing season about 130 days. Lower biomass in our study (ranged from 1 to 7 t ha^-1) compared to those conducted in northern France (1 to 10 t ha^-1) could be correlated with differences in water availability and cultivars, and growing seasons duration (i.e.>150 days in 2006 the study).” to “The growing season in Gansu, China, is cold and dry conditions. Flax plant was irrigated only once, prior to the flax flowering due to dry soils, each plot received 40 mm irrigation. However, the water holding capacities of soils are great due to the cool and humid climate of Northern France. Hence, there is little risk of water deficit. Irrigation was triggered when the soil water content of the 0–30 cm layer was below half of the soil water availability. Lower biomass in our study (ranged from 1 to 7 t ha^-1) compared to those conducted in northern France (1 to 10 t ha^-1) could be correlated with differences in water availability and cultivars.” 

3. What were the ranges of optimal nutritional status N and P for the tested plant, at what stage of development should it be assessed?

Answer: The ranges of optimal nutritional status N for the tested plant were 49~56 g kg⁻¹ DM at 47 DAE, 32~43 g kg⁻¹ DM at 65 DAE, 21~37 g kg⁻¹ DM at 74 DAE, 19~30 g kg⁻¹ DM at 98 DAE and 16~26 g kg⁻¹ DM at 115 DAE, and the P for the tested plant were 3~6 g kg⁻¹ DM at 47 DAE, 2~5 g kg⁻¹ DM at 65 DAE, 2~4 g kg⁻¹ DM at 74 DAE, 2~3 g kg⁻¹ DM at 98 DAE, 1~2 g kg⁻¹ DM at 115 DAE.

4. Another problem that the authors do not address the high pH of soil used in the experiment (approx. 8, I had to go the previous paper). At this pH, P is scarce available and there are disruptions in the plant availability of micronutrients. Hence the observation that we know little about the soil and the plant nutritional status, and the proposed model may only be relevant for this specific condition/particular site. This should be clarified.

Answer: We felt very sorry for you going the previous paper. According to your precious suggestions, we changed the sentence “Therefore, the current study provides diagnosis tool by the relationship between P and N concentrations to estimate the critical P concentration for quantifying the degree of P deficiency. This tool can be used to adjust P fertilization in the following growing seasons. ” to the “Therefore, the current study provides diagnosis tool by the relationship between P and N concentrations to estimate the critical P concentration for quantifying the degree of P deficiency in flax production. This tool can be used to adjust P fertilization in the following growing seasons for the species-specific condition at the pH approximately to 8 of soil.” in the conclusion.

5. What does this work mean for practice?

Answer: This work provides diagnosis tool using the relationship between P and N concentrations by entire the growth period to estimate the critical P concentration for quantifying the degree of P deficiency. This tool can be used to improve nutrient efficiency and reduce nutrient losses in the environment.

6. The discussion is weak and is generally based on comparing the results with other papers. The authors should comment above issue/doubts for the reader.

Answer: Thanks! We amended and improved the content in the discussion for this problem. Hence, we improved the content of 4.1 to “The values of shoot biomass on flax in the current study are lower than those reported by Flénet et al. [38] in a study conducted in northern France. The growing season in Gansu, China, is cold and dry conditions and a short growing season about 130 days. Flax plant was irrigated only once, prior to the flax flowering due to dry soils, each plot received 40 mm irrigation. However, the water holding capacities of soils are great due to the cool and humid climate of Northern France. Hence, there is little risk of water deficit. Irrigation was triggered when the soil water content of the 0–30 cm layer was below half of the soil water availability. Lower biomass in our study (ranged from 1 to 7 t ha^-1) compared to those conducted in northern France (1 to 10 t ha^-1) could be correlated with differences in water availability and cultivars.

Our results observed that P concentration in shoot varied from 1.77−5.36 g kg⁻¹  DM from 47 to 115 DAE, namely seedling to maturity, which a wider range than those in C3 crops reported by Bélanger et al. [20] on wheat (1.6−4.6 g kg⁻¹ DM) from vegetative to late heading stages of development in Canada and by Cadot et al. [40] of rapeseed (5.38−6.52 g kg⁻¹ DM) between inflorescence emergence and ripening and of wheat (3.84−4.53 g kg⁻¹ DM) between tillering and joint stage in Switzerland. This probably due to (i) sampling date were different stages of growth and development among them, which might have caused the different the capability of uptake P; (ii) the difference may be correlated to species, which organ weight ratios and P concentration of organs were significant different; and (iii) the difference could be correlated to environments, especial soils properties and soil microbial phosphorus. Further research is required to do for validation the results in a broader range of environments and species.

 Shoot N concentration in flax ranged between 16.12 g kg⁻¹ DM and 55.70 g kg⁻¹ DM in our study, which a wider range than that reported on linseed in northern France [38], and others C3 crops, such as winter wheat in Canada [24] (14.4−43.4 g kg⁻¹ DM), in Finland (17.3−49.8 g kg⁻¹ DM), and in China (17.3−32.6 g kg⁻¹ DM) [20]. The difference among crops probably explained with diversity in P and N absorption and utilization among different varieties species with various organ weight ratios and P concentration of organs, significant differences exist in P and N concentrations under environment conditions.”

Keywords: most of the keywords are already in the title of the article, which is usually avoided.

Answer: Thanks！We deleted the word “flax”, changed the “nitrogen concentration” to “nitrogen” and the “phosphorus concentration” to “phosphorus”.

 

Mat&Met

1. Even if there is a reference to a previous work, brief information on soil characteristics/fertility should be added, i.e. pH, EC, low, medium or high content of the nutrient.

Answer: Thanks! We added the information on soil characteristics “In brief, the basic information of soil in Dingxi of 2017 plots contains an organic matter of 10.2 g kg^-1, alkali-hydrolyzable N of 48.9 mg kg^-1, available P of 11.7 mg kg^-1 and available K of 122.5 mg kg^-1 and pH of 7.9. The soil in Dingxi of 2018 contains an organic matter of 11.0 g kg^-1, alkali-hydrolyzable N of 50.6 mg kg^-1, available P of 12.6 mg kg^-1 and available K of 135.4 mg kg^-1 and pH of 8.1. And the soil at Yongdeng was described as follow: an organic matter of 9.8 and 7.6 g kg^-1, alkali-hydrolyzable N of 53.9 and 48.2 mg kg^-1, available P of 8.0 and 8.7 mg kg^-1 and available K of 178.3 and 141.6 mg kg^-1, pH of 7.5 and 8.2 in 2018 and 2019, respectively. When P concentration is below 10 mg kg^–1, it is considered low and the optimum soil P concentration is considered above 20 mg kg^–1[36].”

2. 52/53. Unclear/rewrite.

Answer: Thanks! We improved the sentences “In flax, Flénet et al. [16] first proposed a model of critical N dilution curve based on this concept of N dilution. Then, Xie et al. [15] first established a pattern on critical P dilution curve, analogously to the critical N dilution curve was suggested previously by Flénet et al. [16].” to “In flax, Xie et al. [12] established a pattern on critical P dilution curve based on the capsule dry matter”.

3. 103. Whether 10 g of freshly sampled or dried soil were weighted?

Answer: 10 g of dried soil was weighted. We changed the sentences “using a 2-cm diameter auger, naturally dried soil until constant weight. Soil pH was determined using the solution of 10 g soil: 10 mL water. 

4. 119/120. The sentence should be rewritten to the clearer form.

Answer: Thanks! We improved it “All data were subjected to analysis of variance (ANOVA) to compare differences between all studied parameters caused by the variation in P levels and cultivar, using the SPSS (version 19, Inc., Chicago, IL) at a probability level of 5%.”

5. 124-128. This part is unclear. Why do the authors refer here to the results of another study, concerning the potato?

Answer: Thank you very much for valuable suggestions! We improved them “A P-limiting treatment was defined in which additional P resulted in a significant increase in shoot biomass. A non-P-limiting treatment was defined as one in which P application did not lead to an increase in shoot biomass; however, there was a significant increment in shoot P concentration (SPC).”

6. 130. Does the cited work really concern the potato?

Answer: Thank you very much! We changed “similar to approach previously used on potato [21].” to “similar to approach previously used on flax [12].”

7. Section 2.4 should be improved.

Answer: Thanks! Combined the suggestions from two referees, we improved Section 2.4 “All data were subjected to analysis of variance (ANOVA) to compare differences between all studied parameters caused by the variation in P levels and cultivar, using the SPSS (version 19, Inc., Chicago, IL) at a probability level of 5%. The differences among the treatments were calculated using the least significant difference (LSD) test at the 95% confidence level. Different P levels and cultivars were investigated as fixed impacts when present in all experiments. The relationship between P and N concentrations under non-limiting conditions was described by linear regressions of SPSS by a mixed analysis. A non-P-limiting treatment was defined as one in which P application did not lead to an increase in shoot biomass; however, there was a significant increment in shoot P concentration (SPC). The critical P concentration, which is defined as the lowest P concentration required to obtained highest shoot growth [12].

The P nutrition index (PNI) was determined by dividing the P concentration in shoot by the critical P concentration, similar to approach previously used on flax [12]. The relative shoot biomass (RSB) and relative seed yield (RY) were the rates of shoot biomass and seed yield gained for a given P level to their respective peak values observed at a specific year [12]. The coefficients of determination (R²) were calculated using SPSS 20.0.”

8. 137/138. There was no difference in shoot biomass at 47 DAE irrespective of P dose.

Answer: Yes!

9. 140/144 and L. 163/164, L.183/184 and so on. What are the averages, for which treatments, it is not clear. You can add averages in tables if you refer to them.

Answer: Thank you for offering excellent suggestions, we added the averages of different phosphorus levels at the same cultivar for each sample date in the Table 1-6.

10. 155. Remove dot.

Answer: Thanks very much! We did so!

11. 180/181. Unclear/rewrite.

Answer: Thanks! We improved “Averaged, the fertilized treatment increased the N concentration in shoot of flax, compared with the P₀ treatments.” to “Averaged over the P₄₀, P₈₀, P₁₂₀, and P₁₆₀ treatments, the fertilized flax increased the N concentration in shoot, compared with the P₀ treatments.”

12. The bibliography should be unified.

Answer: Thanks very much! We carefully checked all the bibliography in the manuscript.

 

 

Thank you very much for your work concerning our manuscript.

 

Best wishes!

Yaping Xie, Jianping Zhang

 

Author Response File: Author Response.pdf

Reviewer 2 Report

The work in question, entitled “Relationship between Phosphorus and Nitrogen Concentrations of Flax”. It aims to “elucidate the relationship between P and N concentrations of flax during the growing season under within a range of P levels, using the relationship to diagnose and quantify P deficiency the current growing season.”

 

The manuscript needs profound corrections, mainly in the description of the experimental design and adequacy of the statistical analysis. The latter significantly influences the way the results were presented, necessitating a complete rewrite, as well as redoing the discussion and conclusion. The discussion, in particular, needs to be more scientific, regarding the cause and effect relationship, and less comparative with other works in the literature.

 

Details of the observations can be found in the body of the text.

Comments for author File: Comments.pdf

Author Response

Dear Reviewer,

RE: Manuscript ID: agronomy-2216018.

We thank editor and two referees very much for offering some excellent, constructive suggestions for further improvement the manuscript. Accordingly, we have revised the manuscript carefully by following all the comments and suggestions. All those detailed, changes have been followed. We trust that all issues/concerns raised by two referees have been adequately addressed and the manuscript is acceptable for publication in Agronomy.

Below are our responses, point-by-point, to each of the suggestions.

Reviewer 2:

Abstract: Inform experimental design.

Answer: Thanks! Combined with the suggestions from the two referees, we added the sentences “Field experiments were arranged as split plots based on a randomized complete block design. Phosphorus levels (0, 40, 80, 120, and 160 kgP₂O₅ ha⁻¹) were assigned to the main plots, and cultivars (Dingya 22, Lunxuan 2, Longyaza 1, Zhangya 2, and Longya 14) were allocated to the subplots.”

Introduction: Explicitly present, before the objective, the hypothesis for carrying out the research.

Answer: Thanks!

Materials and Methods

1. 89. It is necessary to detail the experiments in the article in question. Including informing the meteorological conditions at the logos of the experimental periods for each location, as well as the averages of the historical series that classify the climates of the places of the experiments. It is also necessary to report the results of soil analyzes in the experimental areas.

Answer: Thanks! According to the advices, we added the contents “(34.26° N, 103.52° E, and altitude of 2060 m) in 2017 and 2018 years”, “(36°02’ N, 103°40’ E, altitude 2149 m) in 2018 and 2019”, “The two sites are continental climate.” “In brief, the basic information of soil in Dingxi of 2017 plots contains an organic matter of 10.2 g kg^-1, alkali-hydrolyzable N of 48.9 mg kg^-1, available P of 11.7 mg kg^-1 and available K of 122.5 mg kg^-1 and pH of 7.9. The soil in Dingxi of 2018 contains an organic matter of 11.0 g kg^-1, alkali-hydrolyzable N of 50.6 mg kg^-1, available P of 12.6 mg kg^-1 and available K of 135.4 mg kg^-1 and pH of 8.1. And the soil at Yongdeng was described as follow: an organic matter of 9.8 and 7.6 g kg^-1, alkali-hydrolyzable N of 53.9 and 48.2 mg kg^-1, available P of 8.0 and 8.7 mg kg^-1 and available K of 178.3 and 141.6 mg kg^-1, pH of 7.5 and 8.2 in 2018 and 2019, respectively. When P concentration is below 10 mg kg^–1, it is considered low and the optimum soil P concentration is considered above 20 mg kg^–1[36].” And “Monthly mean temperatures over the growing season from March to August ranged from -4 to 26℃ at Dingxi and from -5 to 26℃ at Yongdeng. The lowest temperature was recorded in March and highest value in July for four years-sites. The monthly mean temperatures each year was close to the long-term average (30-yr). In brief, total precipitations over the growing season from March to August were 264 and 259 mm at Dingxi and from 275 to 262 mm at Yongdeng. ”

2. 92/94. Considering that the treatments consist of the factors P doses (5 doses) and cultivars (5 cultivars), inform whether it was carried out in a factorial or split-plot scheme. In addition, the description of the treatments presented here differs from those described in article 15: "Four P application rates (0, 40, 80, and 120 kg P₂O₅ ha⁻¹) were applied to two flax cultivars (Longxuan 2 and Dingya 22; ), and five P rates (0, 40, 80, 120, and 160 kg P₂O₅ ha⁻¹) were applied to two other flax cultivars (Longyaza 1 and Longya 14)", informing only 4 cultivars and in one experiment 4 levels of fertilization with P, in the other 5 levels. Here the authors inform 5 levels for all experiments.

Answer: Thank you very much for offering valuable and constructive advices. According to suggestions, we improved “The experiment was a randomized, complete block design with three replicates. Plot size was 5.0m×4.0m. The treatments included five P rates (0, 40, 80, 120, and 160 kg P₂O₅ ha⁻¹) with five cultivars (Dingxi: Longxuan 2 and Dingya 22; and Yongdeng: Longyaza 1, Zhangya 2, and Longya 14, respectively).” to “The experiment was arranged as split plots based on a randomized complete block design with three replicates. Plot size was 5.0m×4.0m. Five P rates (0, 40, 80, 120, and 160 kg P₂O₅ ha⁻¹) were assigned to the main plots, with five cultivars (Dingxi: Longxuan 2 and Dingya 22; and Yongdeng: Longyaza 1, Zhangya 2, and Longya 14, respectively) were allocated to the subplots.”

In addition, the treatments presented here differ from those described in article [12]. 

3. 98. Describe irrigation management, paying attention to the frequency and irrigation depth used to meet the water demand of the plants.

Answer: Thanks! According to suggestions, we improved “Crop water requirements were satisfied by irrigation”. to “Crop was irrigated only once, prior to the flax flowering, each plot received 40 mm irrigation with pipes of 13 cm diameter. A water meter installed at the discharging end of the pipes measured and recorded the amount of irrigation.”

4. 101. Present the result of soil analysis.

Answer: Thank you! The result of soil analysis had present in the manuscript “In brief, the basic information of soil in Dingxi of 2017 plots contains an organic matter of 10.2 g kg^-1, alkali-hydrolyzable N of 48.9 mg kg^-1, available P of 11.7 mg kg^-1 and available K of 122.5 mg kg^-1 and pH of 7.9. The soil in Dingxi of 2018 contains an organic matter of 11.0 g kg^-1, alkali-hydrolyzable N of 50.6 mg kg^-1, available P of 12.6 mg kg^-1 and available K of 135.4 mg kg^-1 and pH of 8.1. And the soil at Yongdeng was described as follow: an organic matter of 9.8 and 7.6 g kg^-1, alkali-hydrolyzable N of 53.9 and 48.2 mg kg^-1, available P of 8.0 and 8.7 mg kg^-1 and available K of 178.3 and 141.6 mg kg^-1, pH of 7.5 and 8.2 in 2018 and 2019, respectively.”

5. 106/107. In consultation carried out in the respective article, it was observed that the soils of the experimental areas are alkaline, pH above 7.0. It is well established in the literature that the

The availability of phosphorus in the soil depends a lot on the pH value, with high risks of P immobilization in conditions of soils with high pH. Informing the care that was taken for this situation does not affect the search results.

Answer: Thanks! Further research is required to do for exploring the cause.

6. 111/112. Check source, the respective article does not describe or validate the respective methodology for determination of dry matter.

Answer: Thanks! We added the content for determination of dry matter “At each year-site sampling date, 30 plants was randomly selected from the two central rows of a plot then separated above ground parts and roots. For chemical analysis, all above ground parts were rinsed with deionized water, then samples was oven-dried at 105 ℃ for half an hour and then at 80℃ until reached a constant weight and shoot biomass was weighed.”

7. 118. Further detail the statistical analysis and present the statistical model used. Inform how the days after the emergency were worked on in the statistical analysis.

Check the pertinence and/or justify the use of the Tukey test for P concentration levels and Days After Emergence. In this case, the Tukey test would be indicated only for the comparison between cultivars, in case of significance for this factor.

Answer: According to suggestions, combined with the advices from the other referee, we amended the content of 2.4 Data analysis “All data were subjected to analysis of variance (ANOVA) to compare differences between all studied parameters caused by the variation in P levels and cultivar, using the SPSS (version 19, Inc., Chicago, IL) at a probability level of 5%. The differences among the treatments were calculated using the least significant difference (LSD) test at the 95% confidence level. Different P levels and cultivars were investigated as fixed impacts when present in all experiments. The relationship between P and N concentrations under nonlimiting conditions was described by linear regressions of SPSS by a mixed analysis.”

8. 124/128. Corresponds to the result. Check the relevance of keeping this text here

Answer: Thanks! Combination with the content of the manuscript, we deleted “A P-limiting treatment, additional P resulted in a significant increase in shoot biomass.”

Results

1. 135. Present significance tables for all variables. Informing the P-value for the individual factors (Doses of P, Cultivars and Days after emergence), as well as for the respective interactions.

Furthermore, in case of interaction, present the P values for the unfolding, as well as the due analysis, according to the nature of the variable. Considering that the literature does not recommend the use of test of means for variables of a quantitative nature.

It is observed that for all the results presented in the tables, the statistical analysis needs to be adjusted, significantly influencing the presentation of the results. Which implies profound changes.

Answer: Thank your valuable suggestions, combined with the excellent advices on the present experiment design; we changed the content from Table 1 to 6. Further details were in Tables of the manuscript.

 Moreover, effect of cultivar and the interaction between cultivar and P doses on shoot biomass, nitrogen and phosphorus concentrations were only at a few sampling date from 47 to 115 DAE, however, this study were to elucidate the relationship between P and N concentrations of flax entire the growing period under within a range of P levels, hence, we concentrated on analysis the effect of P doses on shoot biomass, nitrogen and phosphorus concentrations. We don't know if you can accept our viewpoint.

2. 145/146. For all tables (from 1 to 6), check the observations above, regarding the statistical analysis performed. Considering that there are three factors presented (Cultivar, DAE and P dose), it is necessary to consider the respective interactions and their consequences in the statistical analysis. It is also necessary to adjust the analysis for the use of the average test (Tukey) applied, restricting it for comparison between cultivars, if it is significant. For P and DAE doses, adjust the analysis for regression, when significant.

Answer: Thanks! According to the excellent suggestions, we adjusted the experiment design and analysis for the use of the average test. In the current study, there are two factors (Cultivar and P dose), and DAE is sampling date. Hence, the analysis of regression for P doses by mixed analysis the critical nitrogen and phosphorus concentrations.

 Moreover, effect of cultivar and the interaction between cultivar and P doses on shoot biomass, nitrogen and phosphorus concentrations were only a few sampling date from 47 to 115 DAE, however, this study were to elucidate the relationship between P and N concentrations of flax entire the growing period under within a range of P levels, hence, we concentrated on analysis the effect of P doses on shoot biomass, nitrogen and phosphorus concentrations. We don't know if you can accept our viewpoint.

3. 162/163. Numerically, in fact, this pattern described by the authors is observed. However, the P-values for the columns for these comparisons are not presented. Furthermore, considering that the data are a function of days and P levels, the mean test would not be recommended.

Answer: Thanks! In the present study, DAE is only sampling date.

4. 222/223. Present the legend referring to the cultivars present in the graph.

Answer: Thanks! We added the legend referring to the cultivars in the graph.

5. 224. The discussion needs to be redone, by correcting the statistical analysis and results. It is recommended to carry out a more critical discussion, considering the results from the perspective of cause and effect. Responding "how" and "why" of the response pattern presented by the plants through the applied treatments. and not merely a comparison with other works carried out under different conditions and with different species.

Answer: Thanks! According to your valuable suggestions, combined to the advices the other referee, we amended the discussion.

6. 231/232. Reinforces the need to present climate data in experimental areas during experimental periods. As well as better detailing the management of irrigation.

Answer: Thanks! According to suggestions, we improved “The growing season in Gansu, China, is cold and dry conditions and a short growing season about 130 days.” to “The growing season in Gansu, China, is cold and dry conditions. Flax plant was irrigated only once, prior to the flax flowering due to dry soils, each plot received 40 mm irrigation. However, the water holding capacities of soils are great due to the cool and humid climate of Northern France. Hence, there is little risk of water deficit. Irrigation was triggered when the soil water content of the 0–30 cm layer was below half of the soil water availability.”

7. 246/247. It reinforces the need to carry out a discussion based on the cause-effect relationship, based on the physiological response of the plant. Explaining to the reader "how" and "why" these responses occurred, depending on the treatments used. And do not carry out a discussion based on comparison with other research carried out in different regions, with different species of physiology and possibly different experimental conditions.

Answer: Thanks! According to previous suggestions, we amended and added some contents in the discussion. 

8. 286. Adapt the conclusion according to the necessary adjustments in the statistical analysis, results and discussion.

Answer: Thanks! We did so!

 

Moreover, we added the contents of Author Contributions, Funding, Data Availability Statement, Acknowledgments, and Conflicts of Interest. 

 

Thank you very much for your work concerning our manuscript.

 

Best wishes!

Yaping Xie, Jianping Zhang

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The manuscript has been revised and can be published.

Author Response

1 English language and style are fine/minor spell check required.

Answer: Thank you very much for offering precious suggestions. We check English language and style throughout the manuscript carefully again. We amended the “℃”to “°C ”. And we deleted the numbers of 14 and 41 in the References. 

 

Best wishes!

Yaping Xie, Jianping Zhang

Author Response File: Author Response.pdf

Reviewer 2 Report

Introduction:

 

Clearly write the research hypothesis in the introduction.

 

 

2.4 Data analysis (L 151-158) and Results

 

As previously presented (L 105-109), the experiment was set up in a split plot, with cultivar (C) and phosphorus (P) factors. Thus, there may be a significant individual effect of C and/or P. Also, there may be a significant CxP interaction. When CxP is significant, you need to split it and evaluate the C factor as a function of P doses and the P doses factor as a function of C.

 

  Being a cultivar of a qualitative nature, in which an average test and doses of P of a quantitative nature are applied, the application of a regression is recommended.

 

Note that the question is not whether to apply the Tukey test or the LSD, but that an average test should be applied to compare the cultivars, when more than two, because up to two the ANOVA is conclusive. E The regression to describe the behavioral pattern of responses to doses of P.

 

 

Let's take Table 1 as an example, note that in 2017, when biomass was evaluated in DAE95, it was significant only for C and P individually, not being significant for interaction. In this case, the averages between cultivars are compared, with Digyan22 (4.94 t.ha-¹) greater than Luxuan2 (4.68). As there are two C, the ANOVA result is already conclusive in the case of more cultivars (Table 2) it is necessary to apply an average test, which could be Tukey or LSD.

 

As for the P doses, regression should be performed with the means, to assess the pattern of responses to the doses applied and not perform a test of means.

 

When biomass was evaluated with DAE 65, it was significant for P and CxP. In this case, you only work with the interaction, proceeding with the interaction and comparing the averages of C as a function of the doses of P and performing regression for P as a function of C.

 

Take this example as a reference and correct the results in all tables.

 

 

 

“ Moreover, effect of cultivar and the interaction between cultivar and P doses on shoot biomass, nitrogen and phosphorus concentrations were only at a few sampling date from 47 to 115 DAE, however, this study were to elucidate the relationship between P and N concentrations of flax throughout the growing period under within a range of P levels, hence, we concentrated on analysis the effect of P doses on shoot biomass, nitrogen and phosphorus concentrations. We don't know if you can accept our viewpoint.”

 

 

Regarding the explanation, the point of view was understood. Precisely for this reason, it is necessary to present the hypothesis in the introduction of the work and if the results, from tables 1 to 6, are to base the main objective that the relationship between the levels of P and N, then it is necessary that they be analyzed and presented correctly,

Author Response

1. Introduction:

Clearly write the research hypothesis in the introduction.

Answer: Thanks! We improved the sentences “The objectives of this study were to elucidate the relationship between P and N concentrations of flax during the growing season under within a range of P levels, using the relationship to diagnose and quantify P deficiency the current growing season.” to “The objectives of this study were to elucidate the relationship between P and N concentrations of flax using data from experiments with five P rates, and with various flax cultivars grown under non-limiting P conditions. Specifically, we wanted to determine the critical P concentration using the relationship for shoot growth which could be used to diagnose and quantify P deficiency in flax. ”.

 

2. 4 Data analysis (L 151-158) and Results

2.1 As previously presented (L 105-109), the experiment was set up in a split plot, with cultivar (C) and phosphorus (P) factors. Thus, there may be a significant individual effect of C and/or P. Also, there may be a significant CxP interaction. When CxP is significant, you need to split it and evaluate the C factor as a function of P doses and the P doses factor as a function of C.

 Being a cultivar of a qualitative nature, in which an average test and doses of P of a quantitative nature are applied, the application of a regression is recommended.

 

Note that the question is not whether to apply the Tukey test or the LSD, but that an average test should be applied to compare the cultivars, when more than two, because up to two the ANOVA is conclusive. E The regression to describe the behavioral pattern of responses to doses of P.

 

Let's take Table 1 as an example, note that in 2017, when biomass was evaluated in DAE95, it was significant only for C and P individually, not being significant for interaction. In this case, the averages between cultivars are compared, with Digyan22 (4.94 t.ha-¹) greater than Luxuan2 (4.68). As there are two C, the ANOVA result is already conclusive in the case of more cultivars (Table 2) it is necessary to apply an average test, which could be Tukey or LSD.

 

As for the P doses, regression should be performed with the means, to assess the pattern of responses to the doses applied and not perform a test of means.

 

When biomass was evaluated with DAE 65, it was significant for P and CxP. In this case, you only work with the interaction, proceeding with the interaction and comparing the averages of C as a function of the doses of P and performing regression for P as a function of C.

 

Take this example as a reference and correct the results in all tables.

 

“ Moreover, effect of cultivar and the interaction between cultivar and P doses on shoot biomass, nitrogen and phosphorus concentrations were only at a few sampling date from 47 to 115 DAE, however, this study were to elucidate the relationship between P and N concentrations of flax throughout the growing period under within a range of P levels, hence, we concentrated on analysis the effect of P doses on shoot biomass, nitrogen and phosphorus concentrations. We don't know if you can accept our viewpoint.”

 

Regarding the explanation, the point of view was understood. Precisely for this reason, it is necessary to present the hypothesis in the introduction of the work and if the results, from tables 1 to 6, are to base the main objective that the relationship between the levels of P and N, then it is necessary that they be analyzed and presented correctly,

  

Answer: Thank you very much for understanding us and offering explaining them in more detail! According to your excellent, constructive suggestions for further improvement the manuscript, we rewrote the research hypothesis in the introduction.  Secondly, we added the sentences “This study were to elucidate the relationship between P and N concentrations of flax throughout the growing period, namely from 47 to 115 DAE under non-limiting P conditions. Hence, the data from the experiments conducted in Dingxi of 2017 and 2018 under non-limiting P conditions were pooled with data obtained under non-limiting P conditions in Yongdeng of 2018 and 2019. ” in 3.4 Phosphorus and N concentration relationships in shoot. Finally, we added the content “In addition, effect of cultivar and the interaction between cultivar and P doses on shoot biomass, nitrogen and phosphorus concentrations were only at a few sampling date from 47 to 115 DAE, however, this study were to elucidate the relationship between P and N concentrations of flax throughout the growing period under within a range of P levels, hence, we concentrated on analysis the effect of P doses on shoot biomass, nitrogen and phosphorus concentrations.” In 4.1 Shoot dry matter, phosphorus and nitrogen concentrations.

In addition, we improved the sentence “The relationship between P and N concentrations under non-limiting conditions was described by linear regressions of SPSS by a mixed analysis.” to “The relationship between P and N concentrations under non-limiting conditions was described by linear regressions of SPSS by a combined analysis.” In 2.4. Data analysis. And “The positive relationship between P and N concentrations in shoot identified the strong stoichiometry between P and N in flax.” to “The positive relationship between P and N concentrations under non-limiting P conditions for shoot growth identified the strong stoichiometry between P and N in flax.” In 5. Conclusions.  

 

 

Thank you very much for your work concerning our manuscript.

 

Best wishes!

Yaping Xie, Jianping Zhang