Improving Growth, Yield, and Quality of Tomato Plants (Solanum lycopersicum L) by the Application of Moroccan Seaweed-Based Biostimulants under Greenhouse Conditions

Round 1

Reviewer 1 Report

The manuscript presents the effects of six Moroccan seaweeds based biostimulants application on tomato plant growth, yield and fruit quality parameters analyzed. The subject is of interest and may contribute to the development of  environmentally friendly biostimulant. Overall, I suggest minor alterations in the manuscript, described below.

Page 1, line 21 – Matose or maltose?

Page 4, line 137 – PPE or PEE?

Table 3 (page 5) – Change the commas to points.

Table 4 – Review and adjust the numerical values. For example, ajuste 05.73 to 5.73.

Figure 2 – Lacks specification of the extracts treatments.

Results section

1. The results are presented in a superficial and general manner (control vs. all treatments). I susgest presenting the results shown in tables and figures, in a more detailed manner, highlighting promising seaweed extracts as alternative biostimulants.

2. Why represent the statistical significance using asterisks instead of letters? I believe that letters would be more informative (regarding comparisons among treatments) in table 4 and figures 1 and 2. Some treatments increased while other decreased compared to the control. Authors should justify their choice.

Author Response

• Page 1, line 21 – Matose or maltose? => maltose, it has been corrected in the manuscript.
• Page 4, line 137 – PPE or PEE? => PEE, it has been corrected in the manuscript.
• Table 3 (page 5) – Change the commas to points => Commas has been changed to points.
• Table 4 – Review and adjust the numerical values. For example, adjust 05.73 to 5.73 => numerical values have been adjusted.
• Figure 2 – Lacks specification of the extracts treatments => We think that all extracts treatments are clearly specified in the graphs.

Results section:

• The results are presented in a superficial and general manner (control vs. all treatments). I suggest presenting the results shown in tables and figures, in a more detailed manner, highlighting promising seaweed extracts as alternative biostimulants => We think that results are well detailed.
• Why represent the statistical significance using asterisks instead of letters? I believe that letters would be more informative (regarding comparisons among treatments) in table 4 and figures 1 and 2. Some treatments increased while other decreased compared to the control. Authors should justify their choice. => The first suggestion was taken into consideration, all statistical significance was modified and represented using letters in the tables and figures. Concerning the second comment, no treatment induced a decrease compared to the control, Except the acidity which is a good sign because TA in tomato fruit should decrease with ripening of tomato fruit.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear editor and colleagues,

I have read the entitled manuscript: “Improved growth, yield and quality of tomato plants (Solanum lycopersicum) through soil application of Moroccan seaweed derived biostimulants under greenhouse conditions” with interest, and have now concluded my review.

This is an interesting study focusing on the sustainable production of tomato hybrids (JANA F1) using seaweeds as a growth promoting factor. This is a very noteworthy topic that nowadays concerns several scholars. As a result, the focus of the manuscript is within the aims and scopes of the Agronomy journal.

The manuscript is generally concise, well written and focused, as a result has merit for publication. However, there are several caveats that need to be addressed in order to fully highlight the data presented by the authors.

Please take into consideration these remarks:

Seaweeds as a source has generally a high salt content that can be stressful to plants and further accumulate in the soil contributing to toxicity for following crops. Therefore, water conductivity should have been reported.

Correlting to the above comment, the authors refer that tomato plants were transferred into pots, but I did not find the soil volume/mass; that is crucial and correlates to the volume of irrigation.

Ascorbic acid (vitamin C) is a vital metabolite/antioxidant and a characteristic criterium/index for tomato fruits; the authors should report vitamin c values (since they focus on tomato quality).

L144. How many days until the pruning stage? Was it uniform across all test groups? Also, please clarify “pruning”, since this term can be used for both the removal of lateral (side) branches or the apical stem if the variety is not determinate.

L150. In general, when comparing fruits for phytochemical content or morphological traits, fruits from the 2^nd and 3^rd truss are used, and in some cases even at the same position (1^st, 2^nd fruit etc). If you collected fruits randomly then the diversity could be extended, and ANOVA criteria are not possibly met. I propose to the authors to perform a test of normality (that is a prerequisite for ANOVA).  

L182. Why was hexane was used as a blank? (There are also other chemicals in the buffer)

L186. Please add version and company for SPSS software.

L189. Please add post-hoc (for Tukey test).

L193. Please indicate R version, and packages/libraries used.

L198. Please indicate ANOVA groups (using indexes) across values of seaweed samples

On the discussion section the authors should comment/postulate on

1. why TA levels are negatively correlated to other metabolites and
2. since PEEs can secure water availability, did the water content of tomatoes varied significantly from the control group (I did not observe in the results the water content of fruits)

Based on the above remarks, my recommendation is a major revision

Author Response

• Seaweeds as a source has generally a high salt content that can be stressful to plants and further accumulate in the soil contributing to toxicity for following crops. Therefore, water conductivity should have been reported. = > Polysaccharide extraction method used eliminate salt content in the extracts.
• Correlating to the above comment, the authors refer that tomato plants were transferred into pots, but I did not find the soil volume/mass; that is crucial and correlates to the volume of irrigation. => The soil volume/ mass is: 5L/ 5Kg, it has been mentioned in the manuscript.
• Ascorbic acid (vitamin C) is a vital metabolite/antioxidant and a characteristic criterium/index for tomato fruits; the authors should report vitamin c values (since they focus on tomato quality). => Ascorbic acid is an essential characteristic for the determination of tomato fruit quality after harvest, but unfortunately, some reagents were not disponible in our laboratory, so we had chosen only 4 markers for the analysis of the quality parameters of tomato fruits: The total soluble solid, Acidity, Sugar-acid ratio and Lycopene content.
• L144. How many days until the pruning stage? Was it uniform across all test groups? Also, please clarify “pruning”, since this term can be used for both the removal of lateral (side) branches or the apical stem if the variety is not determinate. => Pruning consists of removing old leaves, basal leaves touching the ground, diseased leaves as well as leaves under the floral bouquet. It is made to maintain a balance between leaves and fruits. In general, it is carried out before harvesting in order to accelerate the ripening of the fruits and facilitate the harvesting and the laying, and also to ensure a good aeration, sunstroke and a better ventilation between the plants (to minimize the risks of cryptogamic diseases ...). In our assay, pruning stage was been done 90 days after transplantation and 20 days before harvest stage. This detail has been added in the manuscript.
• L150. In general, when comparing fruits for phytochemical content or morphological traits, fruits from the 2^nd and 3^rd truss are used, and in some cases even at the same position (1^st, 2^nd fruit etc). If you collected fruits randomly then the diversity could be extended, and ANOVA criteria are not possibly met. I propose to the authors to perform a test of normality (that is a prerequisite for ANOVA) => We performed the Shapiro-Wilk normality test using R: all data were normally distributed except for the parameters: Number of flower buds.

• L182. Why was hexane was used as a blank? (There are also other chemicals in the buffer) => The blank used contains a mixture of hexane, ethanol and acetone (2:1:1).

• L186. Please add version and company for SPSS software => SPSS version is: IBM SPSS statistics 23. It has been added in the manuscript.

• L189. Please add post-hoc (for Tukey test) => It was a mistake, we had used LSD, it has been corrected in the manuscript.

• L193. Please indicate R version, and packages/libraries used). => R version is: 3.5, package: MixOmics, FactoMineR, factoextra and FactoMineR.

• L198. Please indicate ANOVA groups (using indexes) across values of seaweed samples grouping => It has been taken into consideration, all statistical significance was modified and represented using letters in the tables and figures.

• why TA levels are negatively correlated to other metabolites and => total acidity levels are negatively correlated to other metabolites because the TA in tomato fruit decrease with ripening of tomato fruit, so a low acidity content is a good sign of tomato fruit quality.
• since PEEs can secure water availability, did the water content of tomatoes varied significantly from the control group (I did not observe in the results the water content of fruits) => Water content of tomato fruits has not been measured.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Dear editor and colleagues,

I have read the revision of the manuscript and feel that the authors have addressed the majority of my comments/concerns.

The manuscript has been improved and its methods are more clear

As a result, my recommendation is acceptance of the paper