Optimum Moisture Conditions for English Lavender Cuttings Are Drier for Root Development than Shoot Development
Round 1
Reviewer 1 Report
This paper underplays the significance of the findings, which is that the optimum moisture conditions for root development are drier than for shoot development. None of the literature cited had such a finding, so it is worthwhile highlighting its newness. Furthermore, there is a clear changeover point at 4 weeks when development changes from root to shoot, so this change in target moisture could be programmed into the control system at either 4 weeks, or if temperature adjustment is required, at 700 degree-days. The paper also underplays the magnitude of differences between -1 and -2.5 kPa in the shoot growth period after 4 weeks, which from my calculations are 2-8-fold differences. These findings are likely to apply to most other species that are propagated by cuttings, so its significance extends well beyond lavender.
The Introduction and Methods are well written. However, the Results and Discussion section is wordy and could be reduced to one third its current length. I suggest a separate Results section that focuses on the optimum soil moisture for each growth metric. Since there is no change in input costs to set the controller for a higher or lower moisture, the focus should be on determining the optimum for each growth stage. The Results section should be brief and only highlight the points that are later taken up in Discussion and Conclusions. The Figures tell the story very clearly. A separate Discussion section could then focus on the totality of results rather than discussing each parameter separately.
The terms “easily available water (EAW)” and “water buffering capacity (WBC)” are not helpful and don’t appear to be used in any of the literature cited. The focus should instead be on the actual values for moisture tension. The EAW covers a broad range from -1 to -5 kPa that had a wide range of outcomes and it adds nothing to the story to pool them together into a single category.
In Fig 5 it is unclear whether the root characteristics are relative to all cuttings, cuttings that are alive, or cuttings that have roots. Likewise in Figure 6 are the shoots relative to all cuttings or only those with shoots?
The paper should indicate the number of degree-days at which control systems should change from -2.5 to -1.0 kPa. Given an average temperature during the experiment of 26 degrees at 4-weeks is
26 * 4 * 7 = 728 degree-days. Some literature should be cited and to check that the method of calculation is consistent with other horticulture studies, and to provide evidence that the phenology of temperate horticulture crops is consistent with degree-days to the base of zero degrees.
Abstract should include the optimal moistures tensions of -2.5 for root development and -1 kPa for shoot development. Abstract should be updated to accommodate the points made here.
A suggested rewording of the Results section:
The highest survival was achieved at a moisture tension of -2.5 kPa, with lower survival under both drier and wetter conditions (Fig 3a). Drier conditions led to desiccation and death, while under wetter conditions a brown colour developed at the base of the cutting that was symptomatic of fungal infection. Both the -1 and -2.5 kPa tensions also had the highest percentage of cuttings with roots, and there were no significant differences between these treatments (Figure 3b). Few roots developed at the driest tension of -10 kPa, so this moisture treatment was omitted from statistical analysis of root characteristics. Among cuttings that developed roots, there were relatively few significant differences due to moisture treatments in the number of adventitious roots, root length, root fresh weight and root dry weight (Figure 5). The -2.5 kPa treatment had the highest root dry weight at 2 weeks, while the -1 kPa treatment had the greatest number of adventitious roots at 6 weeks. [comment on -5 kPa] Root fresh and dry weight developed mainly between weeks 2 and 4, after which only the number of roots and root length increased. By contrast, shoot development occurred mainly between weeks 4 and 6, and occurred much more rapidly at -1 kPa than -2.5 kPa (Fig 6). Over this period the -1 kPa treatment developed 2.15 as many new leaves as the -2.5 kPa treatment, 2.7 times the new shoot length, 6 times more new shoot fresh weight and 8 times more new shoot dry weight.
(Discussion should then focus on how for most characteristics the optimum was -2.5 kPa until Week 4 when most plant activity was on root development, followed by -1 kPa when shoot development predominated.)
Suggested new title: Optimum moisture conditions for English lavender cuttings are drier for root development than shoot development
Minor suggestions
Line 41 availability within the substrate [7]
Line 167 This confirms
Lines 197-225 Some of this can move to Discussion
Lines 257-258 This is an interesting point that should be included in Results and Discussion sections
Figures 3-6. There is no need for asterisks next to the probability level as this is superfluous.
Author Response
Point 1: Suggested new title: Optimum moisture conditions for English lavender cuttings are drier for root development than shoot development
Response 1: We revised the title as suggested. (Lines 1-5)
Point 2: Abstract should include the optimal moistures tensions of -2.5 for root development and -1 kPa for shoot development. Abstract should be updated to accommodate the points made here.
Response 2: We revised the abstract and updated the statements according to the suggestions. (Lines 26-27)
Point 3: This paper underplays the significance of the findings, which is that the optimum moisture conditions for root development are drier than for shoot development. None of the literature cited had such a finding, so it is worthwhile highlighting its newness. Furthermore, there is a clear changeover point at 4 weeks when development changes from root to shoot, so this change in target moisture could be programmed into the control system at either 4 weeks, or if temperature adjustment is required, at 700 degree-days. The paper also underplays the magnitude of differences between -1 and -2.5 kPa in the shoot growth period after 4 weeks, which from my calculations are 2-8-fold differences. These findings are likely to apply to most other species that are propagated by cuttings, so its significance extends well beyond lavender.
Response 3: Thank you for your suggestions to improve the significance of our findings. Since we only tested with English lavender species, we cannot speculate on the other species. However, we revised the manuscript with more emphasis on the new findings by rewriting the discussion and conclusion, along with strengthening the abstract conclusion. (Lines 237-324)
Point 4: Editorial suggestions
Line 41: “availability within the substrate” in place of “water availability to the substrate (substrate moisture content)”
Line 167 “This confirms” in place of “This suggested”
Response 4: We have revised the changes as suggested. (Lines 44-45, 174)
Point 5: The paper should indicate the number of degree-days at which control systems should change from -2.5 to -1.0 kPa. Given an average temperature during the experiment of 26 degrees at 4-weeks is 26 * 4 * 7 = 728 degree-days. Some literature should be cited and to check that the method of calculation is consistent with other horticulture studies, and to provide evidence that the phenology of temperate horticulture crops is consistent with degree-days to the base of zero degrees.
Response 5: Thank you for the valuable suggestions, and applying growing degree days (GDD) would be a good point to predict the development of the plant. However, our study was conducted in a controlled environment, with an automated irrigation system for cutting propagation, and mentioning GDD in this manuscript may diverge from the most significant findings with moisture levels. We consider applying growing degree days would fit better with another separately designed study with the temperature treatments. If the reviewer still considers adding GDD necessary, we will add calculated GDD in the manuscript.
Point 6: The Introduction and Methods are well written. However, the Results and Discussion section is wordy and could be reduced to one third its current length. I suggest a separate Results section that focuses on the optimum soil moisture for each growth metric. Since there is no change in input costs to set the controller for a higher or lower moisture, the focus should be on determining the optimum for each growth stage. The Results section should be brief and only highlight the points that are later taken up in Discussion and Conclusions. The Figures tell the story very clearly. A separate Discussion section could then focus on the totality of results rather than discussing each parameter separately.
Response 6: We have separated the sections as suggested, and revised the sections accordingly. (Lines 168-228 for results, Lines 237-303 for discussion)
Point 7: A suggested rewording of the Results section:
The highest survival was achieved at a moisture tension of -2.5 kPa, with lower survival under both drier and wetter conditions (Fig 3a). Drier conditions led to desiccation and death, while under wetter conditions a brown colour developed at the base of the cutting that was symptomatic of fungal infection. Both the -1 and -2.5 kPa tensions also had the highest percentage of cuttings with roots, and there were no significant differences between these treatments (Figure 3b). Few roots developed at the driest tension of -10 kPa, so this moisture treatment was omitted from statistical analysis of root characteristics. Among cuttings that developed roots, there were relatively few significant differences due to moisture treatments in the number of adventitious roots, root length, root fresh weight and root dry weight (Figure 5). The -2.5 kPa treatment had the highest root dry weight at 2 weeks, while the -1 kPa treatment had the greatest number of adventitious roots at 6 weeks. [comment on -5 kPa] Root fresh and dry weight developed mainly between weeks 2 and 4, after which only the number of roots and root length increased. By contrast, shoot development occurred mainly between weeks 4 and 6, and occurred much more rapidly at -1 kPa than -2.5 kPa (Fig 6). Over this period the -1 kPa treatment developed 2.15 as many new leaves as the -2.5 kPa treatment, 2.7 times the new shoot length, 6 times more new shoot fresh weight and 8 times more new shoot dry weight.
(Discussion should then focus on how for most characteristics the optimum was -2.5 kPa until Week 4 when most plant activity was on root development, followed by -1 kPa when shoot development predominated.)
Response 7: Thank you for this good suggestion. The results section was revised following the suggestion. (Lines 168-228)
Point 8: The terms “easily available water (EAW)” and “water buffering capacity (WBC)” are not helpful and don’t appear to be used in any of the literature cited. The focus should instead be on the actual values for moisture tension. The EAW covers a broad range from -1 to -5 kPa that had a wide range of outcomes and it adds nothing to the story to pool them together into a single category.
Response 8: Thank you for your kind comments. The terms were removed as suggested to place more emphasis on the actual moisture tension values that were used.
Point 9: Lines 197-225 Some of this can move to Discussion
Response 9: This part was relocated to the discussion section as suggested. (Lines 238-266)
Point 10: Figures 3-6. There is no need for asterisks next to the probability level as this is superfluous.
Response 10: Thank you for your suggestion. The asterisks were removed as suggested. (Figures 3-5)
Point 11: Lines 257-258 This is an interesting point that should be included in Results and Discussion sections
Response 11: Thank you for your kind suggestion. We noted this in the discussion section (Lines 276-278)
Point 12: In Fig 5 it is unclear whether the root characteristics are relative to all cuttings, cuttings that are alive, or cuttings that have roots. Likewise in Figure 6 are the shoots relative to all cuttings or only those with shoots?
Response 12: We used the parameters from the cuttings that were alive. We revised the materials and method to make it clearer. (Lines 153-156)
Reviewer 2 Report
This is a very good paper, covering an important topic. However, there are some points to be addressed before processing further.
Abstract section: does this implicate modular irrigation recommendation?
'The optimal substrate moisture level for high survival and rooting of English lavender cuttings is approximately −2.5 kPa, but the threshold level can be increased to enhance the shoot growth after adventitious roots are established.' maybe it could be clearly stated as a final recommendation.
The introduction section is very well structured, leading to the aims of the presented investigation.
Material and methods section
Why did you opt for soilless substrate? Please evaluate why was this type of substrate used.
If you used a soilless system then please use the term 'substrate' rather than soil when mentioning soil moisture, soil water capacity and similar.
Results and discussion section
Lines 183-185 please discuss this part and add some references regarding other species in similar conditions.
Line 259: please discuss this further, in terms of water savings, irrigation regimes and similar.
Generally, the results and discussion section should be amended with more references, since there are long paragraphs without any citations.
The conclusion should be amended with the applicability of the presented results.
Author Response
Point 1: Does this implicate modular irrigation recommendation?
'The optimal substrate moisture level for high survival and rooting of English lavender cuttings is approximately −2.5 kPa, but the threshold level can be increased to enhance the shoot growth after adventitious roots are established.' maybe it could be clearly stated as a final recommendation.
Response 1: We revised the statements clearer as suggested. (Lines 26-27)
Point 2: Why did you opt for soilless substrate? Please evaluate why was this type of substrate used.
If you used a soilless system then please use the term 'substrate' rather than soil when mentioning soil moisture, soil water capacity and similar.
Response 2: The soilless substrate mix (Sunshine Mix #5, Sun Gro) has fine particles of peatmoss and perlite, and has been used for propagation mix for many horticultural propagators. We followed the industrial practice for the media, and we added the information to the manuscripts. (Lines 90-93)
For the cutting propagation media, a soilless propagation substrate (Sunshine Mix #5; Sun Gro Horticulture, Agawam, MA, USA) with fine particle sizes was used following the industrial practice. Also, the terms between soil and substrate have been revised accordingly throughout the manuscript.
Point 3: Generally, the results and discussion section should be amended with more references, since there are long paragraphs without any citations.
Response 3: The results and discussion have been separated, and revised as suggested. (Lines 168-228 for results, Lines 237-303 for discussion)
Point 4: Lines 183-185 please discuss this part and add some references regarding other species in similar conditions
Response 4: This part was moved to the discussion section with relevant references. (Lines 257-266)
Point 5: Line 259: please discuss this further, in terms of water savings, irrigation regimes and similar.
Response 5: We added the discussion on water saving and water use efficiency using the FDR sensor-based automated irrigation system with the references. (Lines 278-281)
Point 6: The conclusion should be amended with the applicability of the presented results.
Response 6: Thank you for your comment. The conclusion has been revised as suggested.
Lines 318-324: When a precise irrigation system will be applied for the cutting propagation, the optimal substrate moisture levels would depend on the developmental stages of the cuttings, allowing for better growth of root and shoot parts, respectively. These findings are likely to apply to most other species that are propagated by cuttings, and further study to find the best irrigation management practice for cutting propagation of various species would be required.
Round 2
Reviewer 1 Report
Here are a few minor wording change suggestions:
Line 154 (rooted cutting/number of cuttings inserted x 100)
Line 179-181 rapidly within the first week, whereas those at -1.0 and -2.5 kPa maintained a survival of at least 95% until four weeks (Figure 3a). After six weeks, the highest survival…
Line 202-203 slower at -5.0 kPa than -2.5 kPa,
Line 200 -2.5 kPa (missing minus)
Line 279 Likewise, previous research
Line 309 Sufficient moisture (wetter than -5 kPa)
Line 318 system is applied
Author Response
Response to Reviewer 1 Comments (Round 2)
Here are a few minor wording change suggestions:
Line 154. … (rooted cutting/number of cuttings inserted x 100)…
Line 179-181. …rapidly within the first week, whereas those at -1.0 and -2.5 kPa maintained a survival of at least 95% until four weeks (Figure 3a). After six weeks, the highest survival…
Line 202-203. …slower at -5.0 kPa than -2.5 kPa,…
Line 200. …-2.5 kPa (missing minus)…
Line 279. …Likewise, previous research…
Line 309. …Sufficient moisture (wetter than -5 kPa) …
Line 318. …system is applied…
--> We revised as suggested.
Author Response File: 
Author Response.docx
