Inversion Study of Maize Leaf Physiological Information Under Light–Temperature Stress Using Visible–Near Infrared Spectroscopy

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Authors should consider the following points before publication:

• Spectral collection. There is a lot of missing information. How were the spectra collected? What part of the leaves? What were the collection parameters? What reference was used? These should be added to make sure this work is reproduceable
• More regression model details should be added. Authors used PLS and PCR. How many latent variables were used? Why was that number selected?
• Authors selected variables based on correlation with the 2 parameters of interest but in NIR spectroscopy, often, there is information in other parts of the spectra that could be useful. Have authors considered using a larger spectral range?
• How were the SPAD and Pn values determined?

Line 49 – “compound high-temperature …” – do you mean combined?

Line 69 – “accurate advantages” – do you mean accuracy?

Line 140 – “the experiment was conducted from 9:00 to 13:00 on clear, cloudless days” – this work was performed in a temperature and light controlled chamber. Why does it matter if the day was clear or rainy? Were not the measurements made where the plants are?

Figure 5 – I presume the spectra were articially offset as a function of Pn value. If so, that should be clarified. Also, do the PN values correspond to A1-A8 and CK? If so, that should also be added

Line 271. MSC is multiplicative scatter correction, not multivariate

Figures 6 and 7. The legend and some of the titles are in Chinese. That should be translated to English

Author Response

Please refer to the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors prepared a manuscript on the topic "Inversion Study of Maize Leaf Physiological Information under Light-Temperature Stress Using Visible-Near Infrared Spectroscopy". Focusing on maize at the seedling stage, this study examines the response patterns of maize leaf net photosynthetic rate, relative chlorophyll content (SPAD), and Vis/NIR spectral data under eight light-temperature stress conditions.

In this research, the Vis/NIR spectroscopic technology in the absorption mode has been used to establish inversion models for the SPAD and the net rate of photosynthesis using six different spectral pre-processing and modeling combination methods.

The research results employed the correlation coefficients Rc and Rp, and the root mean square errors RMSEC and RMSEP from the training and validation sets as evaluation metrics for the maize leaf physiological information inversion models.

The introduction commences with an examination of the subject's pertinence, accentuating the impact of light and temperature on crops, both in isolation and conjunction, as forms of stress. Concurrently, the merits of Vis/NIR spectroscopy are expounded, showcasing the efficacy of numerous mathematical models in the analysis of agricultural produce. These models demonstrate the correlation between apple diameter and sugar content, the classification of insect infestation in wheat grains, the precise prediction of pH values in silage corn feed, the inversion of physiological information in soybeans, and the detection of ash content in wheat flour.

The literature data are consistent with the objectives of the paper. Single-factor and light-temperature dual-factor stress experiments were conducted under eight light-temperature stress environments, and the physiological parameters and corresponding spectral data of maize seedlings were obtained in a non-destructive manner.

The paper is well structured.

The working methods are presented in a clear and coherent manner.

The results are relevant and discussed in a succinct and adequate manner.

The findings are in alignment with the objectives.

The manuscript is of great academic interest, having been prepared with meticulous care, and the methodologies employed are described with remarkable clarity. Firstly, the study enhances the monitoring of environmental stresses experienced by crops. Secondly, it provides a theoretical foundation for the sustainable cultivation of maize that is both high-yielding and high-quality. The results presented will facilitate a deeper understanding of the physiological spectral responses of maize to light and temperature environments, thus providing essential guidance for precise management of maize growing conditions.

Additional Comments:

The topic is of particular pertinence to agricultural specialists, notably those with a keen interest in the cultivation of corn, as a sound understanding of the optimal light and temperature requirements for this crop is of considerable benefit.

Utilizing two crucial indicators, net photosynthetic rate and relative chlorophyll content, which serve as key parameters for the real-time monitoring of crop growth status and the estimation of yield potential, the photosynthetic efficiency of corn plants was assessed in response to various forms of abiotic stress.

The novelty of the work lies in the spectral preprocessing methods and the combination of modelling techniques used to establish inversion models for the values of relative chlorophyll content and net photosynthetic rate of corn leaves.

The findings align with the presented results and are well-supported by a robust rationale, exhibiting a high level of concordance with existing literature data.

The references cited were published within the last eight years and are pertinent to the subject under discussion. They emphasise the research community's inclination to analyse the impact of two factors (light, temperature) on agricultural crops.

To the figures 1 and 2 the meaning of the letters a and b should be indicated, even if it is known. If it is not specific to the software, the text written in Chinese in figures 6 and 7 should be removed and these figures made clearer.

 

Author Response

Please refer to the attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

• The experimental design is comprehensive with its focus on eight distinct light-temperature stress conditions, but consider expanding the discussion on why these specific stress levels were selected. More justification on the ecological or agricultural relevance of the chosen light intensities (4,400, 8,800, 12,000, and 22,000 lux) and temperature regimes would strengthen the paper's practical applications.
• The results showing PLS-MSC-SG as the optimal spectral combination method for SPAD value inversion and PLS-SNV-SG for net photosynthetic rate are significant. However, a deeper mechanistic explanation of why these specific preprocessing methods perform better would enhance the theoretical contribution of this work. Consider addressing the underlying physical or chemical principles that make these combinations most effective.
• While you've successfully identified spectral sensitive bands (519-583nm and 703-730nm), the paper would benefit from connecting these findings more explicitly to the biochemical properties they represent. Relating specific wavelengths to known photosynthetic pigments or cellular structures would strengthen the interpretation of your results.
• The conclusion correctly identifies limitations regarding different crop varieties and growth conditions, but could explore potential solutions more thoroughly. Consider discussing how machine learning approaches or transfer learning might address the data variability challenges you've identified for practical applications.
• The paper would benefit from a more explicit discussion of how these findings could be implemented in agricultural practice. Specifically, how might farmers or agricultural technologists utilize spectral technology to optimize maize production under varying environmental conditions? A brief section on potential technology development pathways would enhance the paper's impact.

Author Response

Please refer to the email

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for addressing my comments. 

Note that the number of principal components / latent variables used in each model should be added to the manuscript.

I also noted a few english issues in the text added:

line 152- lead in should be replaced by lead to

lines 176 - 183 - "point the probe at the .... Choose the middle of the". THese are instructions not a description of the method. replaced by something like this: The tip of the spectrometer probe was pointed at the ... The middle of the leaf was chosen to avoid ..."

lines 217 - 218 - this sentense should be rewritten

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf