Within-Field Relationships between Satellite-Derived Vegetation Indices, Grain Yield and Spike Number of Winter Wheat and Triticale

Round 1

Reviewer 1 Report

The manuscript aiming at assessing with-field variability of crop yield using Sentinel-2 satellite data is general clear.  However, the current analysis and discussion are poor to show any new findings or deep assessment to the readers. My comments include,

• The discussion is really weak. It is difficult to obtain any deep analysis/suggestion/conclusion from the discussion section, even though more than 10 publications were listed to compare to current study.
• The conclusion section is weak as well. The current edits are better shown in the discussion section.
• The S2 has two NIR bands, which NIR band was used in this study?
• The authors may consider other vegetation indices, especially the indices using the green or three red-edge bands in the assessment.
• More details about grain yield and spikes collection especially the number and locations of samples used in the assessment are required.
• Spatial resolution of the satellite data used in the VIs calculation is unknown.
• Explanations of selecting NDVI, SAVI, mSAVI, IPVI and GEMI are suggested. How about other popular VIs, such as EVI, EVI2, MTVI2 and CIgreen that are widely used for assessing biophysical parameters (e.g., LAI, fAPAR and canopy chlorophyll content ) and crop productivity (e.g., GPP)?
• Please show crop managements, especially sowing date of each field/yield/crop.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The article deals with the assessment evaluation of the heterogeneity of winter cereal stands using vegetation indices calculated from multispectral satellite images. For these purposes, the results of the ground evaluation of yield parameters of cereal stand at three localities in 2017 and 2018 were compared with vegetation indices. The description of the methods in the study is detailed and sufficient, as well as the methodology of the experimental work and statistical evaluation. The results of the study show that the most significant correlation was achieved with the vegetation index NDVI. A change in NDVI of 0.1 represents a change of 2 t/ha.

 

Comments:

• Absence of line numbers on pages 1-15
• Check punctuation in the first two paragraphs on page 2
• The description of the relationship between grain yields and the number of ears would deserve more attention. It would be appropriate to add a more detailed description of the situation with the results of the 2017, when the grain yield at locality B was very low (0.98 t / ha), while the number of spikes per square meter (over 200) was similar to that in 2018, when the yield was 4 t / ha for a given number of spikes.
• According to the paper title and the aim of the study, conclusions should comprise also the description of the results of vegetation indices and the number of spikes
• Page 5 - which atmospheric correction method was used in SCP?
• Figure 5 - It would be interesting to see if the relationship between grain yield and NDVI is how the regression works for all crops
• Figure 7 - what is the cause of the fall in the values of vegetation indices in the second half of June (C - 2017)? Can't these be atmospheric influences (sparse clouds in the images)?

After minor revision and considering the reviewer's comments, I recommend the article to be published.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

The paper is written in a well-organized manner and it is interesting. I have one small comment in the section which explain the relationship between 1)NDVI and grain yield and spike number and 2)the other vegetation indices and grain yield and spike number I think the representation of statistical information in this section such as increase/decrease of coorelation in different location such as A ,B, C with different time period needs one or 2 line explanation to justify the results.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf