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Peer review report 1 on “Canopy scale CO2 exchange and productivity of transplanted paddy and direct seeded rainfed rice production systems in S. Korea”
Agricultural and Forest Meteorology 217 (2016) 365
Contents lists available at ScienceDirect
Agricultural and Forest Meteorology journal homepage: www.elsevier.com/locate/agrformet
Peer Review Report
Peer review report 1 on “Canopy scale CO2 exchange and productivity of transplanted paddy and direct seeded rainfed rice production systems in S. Korea”
1. Original Submission 1.1. Recommendation Minor Revision 2. Comments to Author: This paper examines the carbon exchange of a variety of rice (Oryza sativa subsp. Japonica cv. Unkwang) grown in adjacent fields under flooded and rainfed conditions during a complete growing season. This variety has been developed for particular areas of South Korea but has not been extensively grown under rainfed conditions. Chamber methods were used to quantify NEP and Reco (in bare soil and vegetative plots) which were then used to derive GPP and NPP. I thought this was a very well written manuscript. From the Materials and Methods through to the Results and Discussion I was easily able to understand what the experiment entailed, what the results were, and the author’s interpretation of these results. I found in multiple places after reading a statement I was thinking this is what needs to be discussed next and and there it was discussed in the next statement/paragraph. I thought the authors were thorough in the material/information/figures that needed to be included in this analysis. There are a few minor suggestions to be considered and a few minor errors to resolve. Suggestions 1. Typically, one has to have a fairly large area free of any vegetation to measure Rsoil, which it sounds like these conditions were met in this study. However, this technique of obtaining Rsoil is not the most accurate because roots exudates are easily digested by microbes which in fact contributes to heterotrophic respiration but is not accounted for when measuring in a “root-free” zone. In fact, it is a difficult problem to separate respiration measured from a soil chamber into root and soil components. I would like to see a statement noting that Rsoil measured in the bare soil plots may be underestimating that which would be measured under typical field conditions. This phenomenon has been referred to as
DOI of published article: http://dx.doi.org/10.1016/j.agrformet.2016.07.014. http://dx.doi.org/10.1016/j.agrformet.2016.11.164 0168-1923/
root priming [Y. Kuzyakov, J.K. Friedel, K. Stahr Review of mechanisms and quantification of priming effects. Soil Biol. Biochem., 32 (2000), pp. 1485–1498]. 2. One may interpolate values of the light response coefficients to determine half-hourly GPP values through the entire growing season. The solar radiation, which was measured continuously, is closely related to incident PAR so it may be estimated hourly. Therefore, seasonal totals of GPP may be calculated and compared. This is a suggestion to be considered. I’m not sure this would add much to the present discussion but other “future” studies in rice may appreciate having seasonal totals to compare. 3. On line 410, you note you cannot comment on the additional water loss due to a longer season. One way to estimate this would be to look for previous studies that have defined water use efficiency as the ratio of GPP/ET (see work of P. Steduto and T.C. Hsaio on water productivity). If you have the seasonal total of GPP and you assume the water use efficiency is similar between PR and RF conditions, you may estimate the difference in ET. This is only a suggestion to consider. Specific Comments 1. Abstract. The PR and RF grain weights seem to be swapped here (line 79) compared to the text (line 371). 2. What was planting density in each field? 3. There is a typo in Figure 2 upper right plot - DOY 181 is June 30th, not July 30th. References 4. Line 93 Bouman et al. 5. Line 439 and 467 Munns et al. should be Munns (or Munns et al. 1998 is missing in the references). 6. Line 445 Campbell et al. 7. Line 478 Frageria is spelled incorrectly (should be Fageria). 8. Line 551 Fageria, N.K., Baligar, V.C., 2001 not in the text. Anonymous Available online 4 December 2016
Contents lists available at ScienceDirect
Agricultural and Forest Meteorology journal homepage: www.elsevier.com/locate/agrformet
Peer Review Report
Peer review report 1 on “Canopy scale CO2 exchange and productivity of transplanted paddy and direct seeded rainfed rice production systems in S. Korea”
1. Original Submission 1.1. Recommendation Minor Revision 2. Comments to Author: This paper examines the carbon exchange of a variety of rice (Oryza sativa subsp. Japonica cv. Unkwang) grown in adjacent fields under flooded and rainfed conditions during a complete growing season. This variety has been developed for particular areas of South Korea but has not been extensively grown under rainfed conditions. Chamber methods were used to quantify NEP and Reco (in bare soil and vegetative plots) which were then used to derive GPP and NPP. I thought this was a very well written manuscript. From the Materials and Methods through to the Results and Discussion I was easily able to understand what the experiment entailed, what the results were, and the author’s interpretation of these results. I found in multiple places after reading a statement I was thinking this is what needs to be discussed next and and there it was discussed in the next statement/paragraph. I thought the authors were thorough in the material/information/figures that needed to be included in this analysis. There are a few minor suggestions to be considered and a few minor errors to resolve. Suggestions 1. Typically, one has to have a fairly large area free of any vegetation to measure Rsoil, which it sounds like these conditions were met in this study. However, this technique of obtaining Rsoil is not the most accurate because roots exudates are easily digested by microbes which in fact contributes to heterotrophic respiration but is not accounted for when measuring in a “root-free” zone. In fact, it is a difficult problem to separate respiration measured from a soil chamber into root and soil components. I would like to see a statement noting that Rsoil measured in the bare soil plots may be underestimating that which would be measured under typical field conditions. This phenomenon has been referred to as
DOI of published article: http://dx.doi.org/10.1016/j.agrformet.2016.07.014. http://dx.doi.org/10.1016/j.agrformet.2016.11.164 0168-1923/
root priming [Y. Kuzyakov, J.K. Friedel, K. Stahr Review of mechanisms and quantification of priming effects. Soil Biol. Biochem., 32 (2000), pp. 1485–1498]. 2. One may interpolate values of the light response coefficients to determine half-hourly GPP values through the entire growing season. The solar radiation, which was measured continuously, is closely related to incident PAR so it may be estimated hourly. Therefore, seasonal totals of GPP may be calculated and compared. This is a suggestion to be considered. I’m not sure this would add much to the present discussion but other “future” studies in rice may appreciate having seasonal totals to compare. 3. On line 410, you note you cannot comment on the additional water loss due to a longer season. One way to estimate this would be to look for previous studies that have defined water use efficiency as the ratio of GPP/ET (see work of P. Steduto and T.C. Hsaio on water productivity). If you have the seasonal total of GPP and you assume the water use efficiency is similar between PR and RF conditions, you may estimate the difference in ET. This is only a suggestion to consider. Specific Comments 1. Abstract. The PR and RF grain weights seem to be swapped here (line 79) compared to the text (line 371). 2. What was planting density in each field? 3. There is a typo in Figure 2 upper right plot - DOY 181 is June 30th, not July 30th. References 4. Line 93 Bouman et al. 5. Line 439 and 467 Munns et al. should be Munns (or Munns et al. 1998 is missing in the references). 6. Line 445 Campbell et al. 7. Line 478 Frageria is spelled incorrectly (should be Fageria). 8. Line 551 Fageria, N.K., Baligar, V.C., 2001 not in the text. Anonymous Available online 4 December 2016