Effect of GA3 and Gly Plant Growth Regulators on Productivity and Sugar Content of Sugarcane

Round  1

Reviewer 1 Report

This manuscript investigated the effects of gibberellic acid and glyphosate on the yield of sugarcane. Foliar application of gibberellic acid and glyphosate was effective to improve the yield and/or quality of sugarcane. Application of gibberellic acid in combination with glyphosate was more effective for both sugarcane yield and sugar accumulation. The concentrations of chemical residues in products were lower than that of regulatory standard, therefore, application of these chemicals may be useful for sugarcane production.

Evaluation of predicted prices and net income is not clear. State it clearly how these values were evaluated using reliable data including prices of products, chemicals, and labors. Cite the appropriate references for evaluation.

For chemical treatment, describe how many liters of GA3 and Gly were applied because only the concentrations of these chemicals were shown.

Line126: Use “g” rather than “rpm”.

Line163: “According to the function of GA3, the rate of photosynthesis is enhanced”, this sentence is not clear.

There are numerous errors in the manuscript. English must be checked by natives.

Author Response

v  Reviewer 1:

Comments and Suggestions for Authors

This manuscript investigated the effects of gibberellic acid and glyphosate on the yield of sugarcane. Foliar application of gibberellic acid and glyphosate was effective to improve the yield and/or quality of sugarcane. Application of gibberellic acid in combination with glyphosate was more effective for both sugarcane yield and sugar accumulation. The concentrations of chemical residues in products were lower than that of regulatory standard, therefore, application of these chemicals may be useful for sugarcane production.

Comment 1: Evaluation of predicted prices and net income is not clear. State it clearly how these values were evaluated using reliable data including prices of products, chemicals, and labors. Cite the appropriate references for evaluation.

Reply: Thank for your pointing out. As your suggest, this information have been adding into the 2^nd section (Material and method). All added sentences were highlighted. (line 104-125)

Comment 2: For chemical treatment, describe how many liters of GA3 and Gly were applied because only the concentrations of these chemicals were shown.

Reply: In this study, we used 25 litters for 50m². Thank for your suggestion, we have been provided this information in line 94-104.

Comment 3: Line126: Use “g” rather than “rpm”

Reply: We agree, we should chance into G-forces in order to be easy with different kinds of centrifugation with a different radius from yours. The change is highlighted in the manuscript (line 154).

Comment 4: Line163: “According to the function of GA3, the rate of photosynthesis is enhanced”, this sentence is not clear.

Reply: We agree that this sentence in line 163 was unclear, therefore, we would like to change into: “According to Schaffer [22], GA3 play a critical role in controlling the growth and development of plant and are well known to enhance the photosynthetic efficiency of plant resulting in the increase in the overproduction of sucrose from the leaf”. (line 197).

Comment 5: There are numerous errors in the manuscript. English must be checked by natives.

Reply: We are apologized for this omission. All errors have been checking and correcting carefully

Author Response File: Author Response.doc

Reviewer 2 Report

Nguyen et al., investigated the effect of gibberellin and glyphosate application in the yield and sucrose concentrations of sugar cane. The authors found positive effects of Appling both chemicals independently. Interestingly, applying both at the same time bring synergistic effects in the parameters measured.

While I think that the study was well-conducted, the methods are sound and the study is of value for the scientific community, I think there are some improvements in the presentation of results that could increase the clarity of the study as follows.

·        In the M&M section there is no description on how sucrose was quantified. Authors should also explain how the predicted price (Figure 1), the cost of production (Figure 2), and the net income (Figure 2) were calculated. It is also unclear how the commercial cane sugar (CCS) value was calculated.

·        It is unclear also how the plants were treated. The authors mention that they applied different ppm of the compounds. How much of each compound was applied? Ppm refers to parts per million, so it is concentration, but one can apply 1ml per plant, or 2 liters, so the final amount applied differs considerably, and their effects presumably also. The authors should then clarify this crucial aspect for the general applicability of their study.

·         The authors mention how the different experimental procedures were carried out. The original publication where the methods were initially developed and validated should be referenced.

·        The authors conducted three types of experiments. One in which they only apply GA3, another in which they applied only gly, and one in which they applied both. However, the data are presented in many different forms (Table 2, Figs. 1-3). The authors should choose a standardized manner on how to present their data. All the variables that were measured/calculated and presented for one experiments should also be measured/calculated and presented for all the other experiments to allow direct comparisons, which is the key motivation of this study. I suggest to present then the table 2, and the figures 1 and 3 as figure 2 was presented.

·        Data presented in table 2 should include standard errors for each parameter.

·        Y-axis for figure 1 should start in 0

·        The text needs to be proof-read by an advanced English speaker. For instance “The experiments were taken place” should read “The experiments took place, or were carried out”. “there is no significance different”. Should read “there are no significance differences”. There are many more examples across the text.

·        The use of glyphosate is increasingly being forbidden and many countries have banned their use. The authors should include a paragraph to discuss the consequences of using this compound in a broader context.

Author Response

v Reviewer 2:

Comments and Suggestions for Authors

Nguyen et al., investigated the effect of gibberellin and glyphosate application in the yield and sucrose concentrations of sugar cane. The authors found positive effects of Appling both chemicals independently. Interestingly, applying both at the same time bring synergistic effects in the parameters measured. While I think that the study was well-conducted, the methods are sound and the study is of value for the scientific community, I think there are some improvements in the presentation of results that could increase the clarity of the study as follows.

Comment 1: In the M&M section there is no description on how sucrose was quantified. Authors should also explain how the predicted price (Figure 1), the cost of production (Figure 2), and the net income (Figure 2) were calculated. It is also unclear how the commercial cane sugar (CCS) value was calculated.

Reply: Thank for your pointing out. As your suggest, this information have been adding into the 2^nd section (Material and method). All added sentences were highlighted. (line 104-125).

Comment 2: It is unclear also how the plants were treated. The authors mention that they applied different ppm of the compounds. How much of each compound was applied? Ppm refers to parts per million, so it is concentration, but one can apply 1ml per plant, or 2 liters, so the final amount applied differs considerably, and their effects presumably also. The authors should then clarify this crucial aspect for the general applicability of their study.

Reply: Thank for your comments. it is really necessary information. This information was added in the M&M (line 94-104).

Comment 3: The authors mention how the different experimental procedures were carried out. The original publication where the methods were initially developed and validated should be referenced.

Reply: We are apologized for this omission. The citations were added in the suitable position in the manuscript.

Comment 4: The authors conducted three types of experiments. One in which they only apply GA3, another in which they applied only gly, and one in which they applied both. However, the data are presented in many different forms (Table 2, Figs. 1-3). The authors should choose a standardized manner on how to present their data. All the variables that were measured/calculated and presented for one experiments should also be measured/calculated and presented for all the other experiments to allow direct comparisons, which is the key motivation of this study. I suggest to present then the table 2, and the figures 1 and 3 as figure 2 was presented

Reply: Thanks very much. We had conducted the same manner  of comparison including: the length of internode, the length of stem, diameter of stalk, the fresh weight, the CCS values and productivity as well as the net income for all experiment. However, after analyzing data, we found that the value of productivity as well as the net income was non-significant difference among the concentration of Gly. The only benefit of Gly was the increase of CCS value, therefore, we presented data only in this aspect. In the case of dual combination, we want to know whether Gly can be synergistic effects with GA3. We compared based on the basic criteria of economic in sugarcane which are set up by a cane mill such as CCS value, fresh weight/stem (that was used to calculate productivity) and the net income. Then, all information of the length of internode, of the length of stem, the fresh weight, the CCS values and productivity as well as the net income for dual GA3/Gly were provided in figure 3 to clarify the dual effect of GA3/Gly on sugarcane.

Comment 5: Data presented in table 2 should include standard errors for each parameter.

Reply: As your comment, the value of standard errors for each parameter have provided. (table 2, line 227).

Comment 6: Y-axis for figure 1 should start in 0

Reply: Y-axis for figure 1 was correct to start in 0

Comment 7: The text needs to be proof-read by an advanced English speaker. For instance “The experiments were taken place” should read “The experiments took place, or were carried out”. “there is no significance different”. Should read “there are no significance differences”. There are many more examples across the text.

Reply Many thanks for your reading and suggesting. All the errors have fixed. The changes are written with red color.

Comment 8: The use of glyphosate is increasingly being forbidden and many countries have banned their use. The authors should include a paragraph to discuss the consequences of using this compound in a broader context.·        .

Reply: We agree with this comment. Actually, glyphosate is being forbidden in some countries due to the concern related to probable carcinogen when exposure but the evidence hasn’t been clarified and some countries have still been allowing use in agriculture. However, the function of GLy on recoverable sugar has been proved in a long history of sugarcane researches [34-36]. Although the application of Gly causes a remarkable reduction in productivity, both the farmer and the mill expose their satisfaction about economically advantageous of increment of sugar yield [ 37,38]. Therefore, the detection of the trace amounts of Gly in cane juice after the application is very important in order to fate the use of this herbicide in agricultural fields.

We have discussed the use of Gly in the line 332-339

Author Response File: Author Response.doc

Reviewer 3 Report

This is a competently conducted study.  There is nothing surprising about the effects of glyphosate and GA on sugar yields.  However, the glyphosate residue results are timely and will be of interest. 

The English needs improvement. 

The authors might compare their glyphosate residue results with results from glyphosate-resistant sugar beet which is exposed to much higher doses of glyphosate (J. Agric. Food Chem. 2019, 67:2061-2065).

What salt of glyphosate was used?  Was the free acid form used?  What was the dose of glyphosate sprayed on the plants in g/ha?

Line 126 – rpm is meaningless. Give g force value.

Author Response

v  Reviewer 3:

Comments and Suggestions for Authors

This is a competently conducted study.  There is nothing surprising about the effects of glyphosate and GA on sugar yields.  However, the glyphosate residue results are timely and will be of interest.

Comment 1: The English needs improvement

Reply: Many thanks for your reading and suggesting. All the errors have fixed. The changes are written with red color.

Comment 2: The authors might compare their glyphosate residue results with results from glyphosate-resistant sugar beet which is exposed to much higher doses of glyphosate (J. Agric. Food Chem. 2019, 67:2061-2065).

Reply: We are total agree with this comment. The similitude is added in the manuscript at line 348-353.

Comment 3: What salt of glyphosate was used?  Was the free acid form used?  What was the dose of glyphosate sprayed on the plants in g/ha?

Reply: In this study, we used Glyphosate isopropylamine salt. The dosage was 40g a.e/ha (200ppm), 30g a.e/ha (150ppm), and 20g a.e/ha (100ppm)

Comment 4: Line 126 – rpm is meaningless. Give g force value

Reply: We agree, we should chance into G-forces in order to be easy with different kinds of centrifugation with a different radius from yours. The change is highlighted in the manuscript (line 154).

Regarding to several comments from these reviewers we fully upgraded our manuscript to match with scientific standard of the Journal

With my best regards,

On behalf  of authors,

Tran Ngoc Quyen, Ph.D. Assoc.Prof.

Head of Department - Materials and Pharmaceutical chemistry

Institute of Applied Materials Science-Vietnam Academy of Science and Technology

Phone : 84.1256785648 or 84.901357290, Fax : 84.838236073

Email: [email protected] or [email protected]

Author Response File: Author Response.doc

Round  2

Reviewer 1 Report

I am satisfied with the authors response and the revised manuscript, and I have no further questions.