Breeding Cowpea for Adaptation to Intercropping for Sustainable Intensification in the Guinea Savannas of Nigeria
, Kamaluddin T. Aliyu 1, Abdullahi I. Tofa 1, Reuben Solomon 1 and Olalekan J. Olasan 4Round 1
Reviewer 1 Report
This manuscript had evaluated the performance of some newly developed cowpea breeding lines for adaptation to intercropping systems. This manuscript was of significance for the agricultural production of the Guinea savannas in Nigeria. The introduction section of this manuscript was well written. But in my opinion, the other sections in this manuscript need to be deeply revised.
1. Line 147-152, 161-162: Why are 30 lines described in the manuscript, but only 25 lines listed in Table 1?
2. Line 158, 190: The nutrient content of fertilizer should be described N 15%: P2O5 15%: K2O 15%.
3. Line 154-156, 187-197: It is recommended to use a diagram to clearly show the intercropping pattern, especially the spaces between the crops.
4. There are more acronyms in the manuscript lacking the specific meaning, such as LER, DFF, D50F, D95M, WAP, and so on, suggest supplementing them.
5. The significance difference between all cowpea lines in the table 2-7 is not indicated, and it is not clear whether there is a difference significance between the different indicators of these cowpea lines.
6. The results section of the manuscript only repeat mostly the same data as the table, and it is suggested to analyze the significance of the difference between different indicators of different lines, and then compare and describe.
7. It is suggested that all indexes of different cowpea lines should be evaluated comprehensively to select the optimal cowpea line.
8. The discussion section of the manuscript did not target the research results in detail. Recommend rewriting this section.
The language is fine. I recommend this manuscript to be accepted in this journal after the above-mentioned points are revised.
Author Response
Response to Reviewer 1 Comments
Point 1: This is a straightforward and generally well-done and well-presented research study evaluating potential lines of cowpea for use in intercrops with maize in the Guinea savanna. The authors succeed in identifying unique high-performing lines, including large-seeded brown cowpeas sought by farmers, in the relevant context of intercropping, which is not often done. I feel this is a valuable contribution which should be shared, with some requests for improvement.
Response 1: This is a compliments from the reviewer, thank you.
Point 2: My main concern is the quality and, in some cases, absence of mean separations for the ANOVAs used. Generally, the use of Least Significant Difference is not appropriate with so many treatments; one is likely to find erroneous significant differences simply due to chance when there are a large number of treatments, so a test with pair-wise comparisons should be used such as the Tukey HSD test. This applies especially to the first experiment (results in Table 1), but the rest as well in my view. Additionally, there are no mean separations done for the intercrop values presented in Tables 3 & 4, though the ANOVA indicates p<.0001 for grain yield (Table 3) and p<0.05 for seed size at Makurdi station (Table 4).
Response 2: We used p-values in the tables, which indicates if significant differences exist between the cowpea lines. We have included the SED for the mean separation in all the Tables.
Typically, in studies like this aimed at selecting varieties for improved productivity, lines with the highest grain yield or trait of preference are selected when significant differences exist.
Point 3: I also am unclear as to why tests for the Main Plot effect are not presented, i.e. intercrop vs. sole crop though it is stated that the latter is always higher (l. 270-271). ANOVA for partial LER is not indicated either and should be corrected, or an explanation offered as to why this is not presented.
Response 3: It is true that the results can be presented to reflect the main effects. However, that is not the objective of this work. By presenting the main effects, we can only be able to understand the overall performance of the systems, but not that of the individual cowpea genotypes under the systems. Normally that overall performance when compared, it is expected that the intercropped system will always rate higher, because it combines the yield of two crops. Therefore, such comparison is not advised for agronomic or breeding sense. To overcome that, the LER index is used
to compare the productivity of intercropping systems of production. It is also worthy to note that the two systems are in this context are not uniform, so the two systems can be considered as stress and non-stress environments, so an index of selection is usually recommended in such circumstance. SED for LER has been included
Point 4: A diagram of the sole and intercropping planting arrangement would be helpful.
Response 4: The intercropping planting pattern arrangement has been included
Point 5: The table captions should include abbreviations and a statement of the statistical test used to derive the results
Response 5: Abbreviations are now defined, and mean separation is included.
Point 6: The Introduction mentions the increasing use of intercropping with cowpea in the Guinea savanna of Nigeria; the crops with which it is mixed are not stated, though maize is implied from the experiments described. Only ". . . these crops . . ." are mentioned in l. 57, but they are never defined. In addition, it would be good to state the productivity of such intercrops where data is available (perhaps from the areas to the north), particularly LER.
Response 6: Other cereal crops used for intercropping have been included
Point 7: Additional references should be provided to support some of the statements in the Introduction, e.g. lines 45-50 and 61-65.
Response 7: Additional references added.
Point 8: There are several small errors (e.g. "were" should be "was" on l. 203; "The" should be "This" on l. 365) but the English is generally quite good. The beginning of Section 3.2 (ll. 254-256) is unclear and should be reworded. The word "text" is repeatedly used for "test" ll. 397-400.
Response 8: Errors fixed.
Author Response File: 
Author Response.docx
Reviewer 2 Report
This is a straightforward and generally well-done and well-presented research study evaluating potential lines of cowpea for use in intercrops with maize in the Guinea savanna. The authors succeed in identifying unique high-performing lines, including large-seeded brown cowpeas sought by farmers, in the relevant context of intercropping, which is not often done. I feel this is a valuable contribution which should be shared, with some requests for improvement.
My main concern is the quality and, in some cases, absence of mean separations for the ANOVAs used. Generally the use of Least Significant Difference is not appropriate with so many treatments; one is likely to find erroneous significant differences simply due to chance when there are a large number of treatments, so a test with pair-wise comparisons should be used such as the Tukey HSD test. This applies especially to the first experiment (results in Table 1), but the rest as well in my view. Additionally, there are no mean separations done for the intercrop values presented in Tables 3 & 4, though the ANOVA indicates p<.0001 for grain yield (Table 3) and p<0.05 for seed size at Makurdi station (Table 4).
I also am unclear as to why tests for the Main Plot effect are not presented; i.e. intercrop vs. sole crop though it is stated that the latter is always higher (l. 270-271). ANOVA for partial LER is not indicated either, and should be corrected, or an explanation offered as to why this is not presented.
Otherwise I would like to point out a couple other opportunities for improvement:
--A diagram of the sole and intercropping planting arrangement would be helpful.
--The table captions should include abbreviations and a statement of the statistical test used to derive the results.
--The Introduction mentions the increasing use of intercropping with cowpea in the Guinea savanna of Nigeria, the crops with which it is mixed are not stated, though maize is implied from the experiments described. Only ". . . these crops . . ." are mentioned in l. 57, but they are never defined. In addition, it would be good to state the productivity of such intercrops where data is available (perhaps from the areas to the north), particularly LER.
--Additional references should be provided to support some of the statements in the Introduction, e.g. lines 45-50 and 61-65.
There are several small errors (e.g. "were" should be "was" on l. 203; "The" should be "This" on l. 365) but the English is generally quite good. The beginning of Section 3.2 (ll. 254-256) is not clear and should be reworded. The word "text" is repeatedly used for "test" ll. 397-400.
Author Response
Response to Reviewer 1 Comments
Point 1: This manuscript had evaluated the performance of some newly developed cowpea breeding lines for adaptation to intercropping systems. This manuscript was of significance for the agricultural production of the Guinea savannas in Nigeria. The introduction section of this manuscript was well written. But in my opinion, the other sections in this manuscript need to be deeply revised.
Response 1: This is a compliment from the reviewer
Point 2: Line 147-152, 161-162: Why are 30 lines described in the manuscript, but only 25 lines listed in Table 1?
Response 2: The correction has been taken care of. The table with 30 lines (the derived lines from the crosses, commercial varieties and local cultivars) has been inserted appropriately.
Point 3: Line 158, 190: The nutrient content of fertilizer should be described N 15%: P2O5 15%: K2O 15%.
Response 3: This has been corrected.
Point 4: Line 154-156, 187-197: It is recommended to use a diagram to clearly show the intercropping pattern, especially the spaces between the crops
Response 4: This has been done.
Point 5: There are more acronyms in the manuscript lacking the specific meaning, such as LER, DFF, D50F, D95M, WAP, and so on, suggest supplementing them.
Response 5: The acronyms have been defined in the appropriate sections.
Point 6: The significance difference between all cowpea lines in the table 2-7 is not indicated, and it is not clear whether there is a difference significance between the different indicators of these cowpea lines.
Response 6: We used p-values in the tables indicating significant differences between the cowpea lines. Mean separation (SED) has been included.
Point 7: The results section of the manuscript only repeats mostly the same data as the table, and it is suggested to analyze the significance of the difference between different indicators of different lines, and then compare and describe.
Response 7: Correction effected.
Point 8: It is suggested that all indexes of different cowpea lines should be evaluated comprehensively to select the optimal cowpea line.
Response 8: Correction effected.
Point 9: The discussion section of the manuscript did not target the research results in detail. Recommend rewriting this section.
Response 9: We have described other indexes that were not captured earlier on.
Point 10: The language is fine. I recommend this manuscript to be accepted in this journal after the above-mentioned points are revised.
Response 9: Compliments from the review, thank you.
