Genetic Improvement of Post-Heading Root Morphology and Physiology Facilitating Yield Increase of japonica Inbred Rice
Round 1
Reviewer 1 Report
Abstract: Nicely written make following corrections:
Ln: 16. Write 8 in place of 8.0%. ....make it, .....had 8 and 4.3% higher grain....
Ln 18-19: Remove repetition of heading and maturity....modify sentences accordingly.
Ln 22. Remove "alongwith cultivar improvement". Mention in which rice lines the reported parameters were all increased.
Introduction: well written. Issues to be addressed have been appropriately brought out and study objectives are very clear.
Materials and methods:
Sufficient details about experimentation have been provided. Some mistakes as given below were noted which may be corrected:
Mention appropriately that year was considered as random effect in the statistical analyses.
Page 3 Ln: 95. A randomized-block design was conducted used in this field experiment
ln: 96. delete at two years. Write 'during both study years'.
....four seedlings per hill at a spacing of 30 cm × 12 cm on 97 12 June at two years. Why four seedlings were planted at each hill. generally 2 seedlings are planted per hill. Avoid writing 'at two years' Instead write during two years or both years.
Ln: 104: Briefly mention local practices followed.
Ln: 134: ..The data were processed (write were in place of was).
Results
Table 2. Check the unit of yield . Is it t/ha or kg/ha. Also, check unit of kernel weight.
Ln: 142: 8.0% and 4.3%. ; 8 and 4.3%
Ln: 174. ----higher root biomass of for 15-30 cm....
Discussion: The results have been nice explained with proper reasoning and literature. Overall the discussion and conclusion parts are excellent.
Though the manuscript is of high standard, te authors need to read it more carefully for mistakes, some of which I have pointed out. Check the units of data doubly.
Author Response
Point 1: Abstract: Nicely written make following corrections: Ln: 16. Write 8 in place of 8.0%. ....make it, .....had 8 and 4.3% higher grain....
Response 1: Revised as suggested.
Point 2: Ln 18-19: Remove repetition of heading and maturity....modify sentences accordingly.
Response 2: Good suggestion. We changed as follows: "Compared with the 1990´s and the 2000´s rice, the 2010´s rice had higher shoot biomass at heading and maturity (P < 0.05), as well as root biomass (P < 0.05), especially for root biomass of 15-30 cm soil depth." in Lines 18-20 in the revised manuscript (clean version).
Point 3: Ln 22. Remove "along with cultivar improvement". Mention in which rice lines the reported parameters were all increased.
Response 3: Revised as suggested.
Point 4: Introduction: well written. Issues to be addressed have been appropriately brought out and study objectives are very clear.
Response 4: We appreciate very much for your recognition of the Introduction.
Point 5: Materials and methods: Sufficient details about experimentation have been provided. Some mistakes as given below were noted which may be corrected: Mention appropriately that year was considered as random effect in the statistical analyses.
Response 5: Good suggestion. We seek the help of Prof. Xu (Prof. Chenwu Xu, a specialist in data analysis) in our university about the statistical analysis in this study. Following with the suggestions of Prof. Xu, we changed the description in statistical analysis, and such information was follows in Lines 138-146 (clean version): “Data were subjected to a two-way analysis of variance (ANOVA) to assess the effects of year, cultivar type, and interactions between the two on the grain yield and its components, biomass of shoot and root, LAI, leaf photosynthetic rate, SPAD values, root length and volume, root oxidation activity, and root bleeding rate. When the treatment means were different, the LSD test was performed to identify significant differences at P < 0.05. Data of three cultivars in the same cultivar type were averaged because there were no significant differences in all determined parameters among three cultivars in the same cultivar type. All data analyses were conducted with SPSS 17.0 Software (SPSS Inc., Chicago, USA).”
Point 6: Page 3 Ln: 95. A randomized-block design was conducted used in this field experiment
Response 6: We changed “used” with “conducted” in Line 99 in the revised manuscript (clean version).
Point 7: ln: 96. delete at two years. Write 'during both study years'.
Response 7: Revised as suggested in Line 100 in the revised manuscript (clean version).
Point 8: ....four seedlings per hill at a spacing of 30 cm × 12 cm on 97 12 June at two years. Why four seedlings were planted at each hill. Generally 2 seedlings are planted per hill. Avoid writing 'at two years' Instead write during two years or both years.
Response 8: Good suggestion. For japonica inbred rice, four seedlings were always recommended under conventional transplanting density under local conditions such as 27.8 × 104 per hill (30 cm × 12 cm) in our study, which was confirmed in previous studies (Qian Y F, Zhang H C, Wu W G, Chen Y, Li J, Guo C H, Zhang Q, Dai Q G, Huo Z Y, Xu K, Wei H Y. Effects of seedlings number per hill on grain yield and quality in different panicle types of mechanical transplanted japonica rice. Acta Agron Sin, 2009, 35:1689–1707 (in Chinese with English abstract); Hu Y J, Cao W W, Qian H J, Xing Z P, Zhang H C, Dai Q G, Huo Z Y, Xu K, Wei H Y, Guo B W, Gao H, Sha A Q, Zhou Y Y, Liu G L. Effect of planting density of mechanically transplanted pot seedlings on yield, plant type and lodging resistance in rice with different panicle types. Acta Agron Sin, 2015, 41:743–757 (in Chinese with English abstract)).
Besides, we changed “during two years” with “at two years” in Line 102, 173, and 224 in the revised manuscript (clean version).
Point 9: Ln: 104: Briefly mention local practices followed.
Response 9: Good suggestion. We changed as follows: “Chemical controls of pests, disease, and weed were performed following local practices.” in Lines 107-108 in the revised manuscript (clean version).
Point 10: Ln: 134: ..The data were processed (write were in place of was).
Response 10: Revised as suggested.
Point 11: Results
Table 2. Check the unit of yield. Is it t/ha or kg/ha. Also, check unit of kernel weight.
Response 11: Good suggestion. We revised the unit of yield as t ha-1 rather than kg ha-1. Besides, we changed “kernel weight” with “1000-grain weight”, and also for the unit (g rather than mg).
Point 12: Ln: 142: 8.0% and 4.3%. ; 8 and 4.3%
Response 12: Revised as suggested.
Point 13: Ln: 174. ----higher root biomass of for 15-30 cm....
Response 13: Revised as suggested.
Point 14: Discussion: The results have been nice explained with proper reasoning and literature. Overall the discussion and conclusion parts are excellent. Though the manuscript is of high standard, the authors need to read it more carefully for mistakes, some of which I have pointed out. Check the units of data doubly.
Response 14: We appreciate very much for your recognition of the Discussion and Conclusion. As suggested, we checked carefully about the spelling, grammar rules, and units of data.
Thank you for your professional comments and precious time to improve this manuscript.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Check the numbering in the text. I detected numbering error (example: line 50 should be 12 instead of 11).
Material and methods
How many varieties where leased during the three decades covered in the study? If there are more than the ones used in the study, it is worth mentioning the total number and stress the reason for selecting these nine. To proof the point the lines should not be too different from the beginning, thus, more needs to be mentioned than just saying they have similar growth pattern.
The author should give, in the discussion, his opinion on how these information can be used by breeders to developed better cultivars (high yielding combined with better root system). It would add value to the work.
Author Response
Point 1: Check the numbering in the text. I detected numbering error (example: line 50 should be 12 instead of 11).
Response 1: Good suggestion. We changed as follows “Ning et al. [12] reported that …..” in Line 49 in the revised manuscript (clean version). We also checked and corrected similar mistakes throughout the whole manuscript.
Point 2: Material and methods
How many varieties were leased during the three decades covered in the study? If there are more than the ones used in the study, it is worth mentioning the total number and stress the reason for selecting these nine. To proof the point the lines should not be too different from the beginning, thus, more needs to be mentioned than just saying they have similar growth pattern.
Response 2: Good suggestion. We collected such information from the website http://www.ricedata.cn. Totally, 67 rice cultivars were officially released from 1990 to 2018 (the beginning year of our study), which was recommended for the central region of Jiangsu, east China (location of the experimental site, Figure A). In our study, nine rice cultivars were selected mainly considering the following reasons: (1) although 67 rice cultivars were released from 1990 to 2018, seeds of most these cultivars were not preserved well by their breeding institutes and not able to collect again, mainly due to they were not popular among local farmers with a limited planting area. (2) these selected nine cultivars were all released by local breeding institutes and were widely adopted by local farmers during historical periods. For instance, the cumulative planting area of Wuyujing 3 was up to 6.1 million hectares by the end of 2019, which was the most popular rice cultivar in the 1990s in east China (www.ricedata.cn, accessed on: 10 August 2021). In recent years, Nanjing 9108 with excellent cooking and eating qualities was grown widely [20], with a cumulative growing area of 1.8 million hectares as of 2019 (www.ricedata.cn, accessed on: 10 August 2021). The rice cultivars were considered representative during the genetic improvement of japonica inbred rice since the 1990s, and always chosen as the control in rice cultivar regional trials conducted in Jiangsu, east China. Besides, these rice cultivars shared a similar heading date ranging from 8/20 (month/day) to 8/25 (month/day), as well as growth pattern (total growth period ranged from 150 d to 156 d). Based on the information above, these nine cultivars were selected in this study, and such information was also included in Lines 82-93 in the
revised manuscript (clean version).
Figure A. Location of the experimental site
Point 3: The author should give, in the discussion, his opinion on how these information can be used by breeders to develop better cultivars (high yielding combined with better root system). It would add value to the work.
Response 3: Good suggestion. We added the following as suggested: “The above results confirmed the contribution of post-heading root morphology and physiology to yield gain during the genetic improvement of japonica inbred rice. Such results also brought some implications in future breeding programs: (i) in our study, root biomass at heading correlated positively with shoot biomass at heading and maturity (P < 0.05 or P < 0.01) and grain yield (P < 0.01) (Table 7). This result suggested coordination of the root and shoot after heading was critical for maintaining grain yield of rice [11], and a well-established root system after heading could be used as a selection criterion for future rice root breeding. (ii) grain-filling duration is a crucial period for grain yield formation of cereals, also senescence phase of leaf and root, two important sources for sink filling [36]. As described previously, root length and volume, root oxidation activity, and root bleeding rate were closely associated with shoot stay-green and biomass accumulation after heading (Table 8). Hence, parents with superior root morphology-physiology should receive more attention for developing rice cultivars with higher yield potential. ” in Lines 319-331 in the revised manuscript (clean version).
Thank you for your professional comments and precious time to improve this manuscript.
Author Response File: Author Response.docx
