Plant Architecture Influences the Population Transpiration and Canopy Temperature in Winter Wheat Genotypes

Round 1

Reviewer 1 Report

The article's objective was to demonstrate how the upright-leafed compact type and flat-leafed loose type of wheat architectures influence canopy features (population density and canopy temperature depression) and control wheat water consumption under rain-fed and supplemental irrigation conditions. The chosen topic is important to understand how to conserve irrigation water without significantly decreasing yields by utilizing unique plant architecture. However, my attention has been addressed to minor aspects. Not only due to the politeness of the writing, however, I warmly suggest to concern the following:

-       The text has a few grammatical and grammatical errors. It needs a thorough rewrite.

-       In lines 315: Please correct the sentence: “The similar ET and TET indicated Jinmai 47 conserves more water than Jing411, since it had a higher PD”. As shown in figure 2:  Jinmai 47 conserves less water than Jing411, in spite of it had a higher PD.

-       In lines 322: Please add figure’s symbols as “----under (A) rain-fed (RF) and (B) supplemental irrigation (SI)”.

-       In lines 337: Please change “IF” to “RF”.

 

-       In lines 452: Please change “Blum also stressed--------- drought stress [49].” to “Blum [49] also stressed-----”.

Author Response

Reviewer1

-       The text has a few grammatical and grammatical errors. It needs a thorough rewrite.

Reply: The manuscript’s language has been modified by a English native speaker who is also familiar with the subject matter.

 

-       In lines 315: Please correct the sentence: “The similar ET and TET indicated Jinmai 47 conserves more water than Jing411, since it had a higher PD”. As shown in figure 2:  Jinmai 47 conserves less water than Jing411, in spite of it had a higher PD.

Reply: With a higher population density, Jinmai 47 did not consume more water, as showed by the similar ET and TET, indicating that Jinmai 47 conserves more water relative to Jing411.

 

-       In lines 322: Please add figure’s symbols as “----under (A) rain-fed (RF) and (B) supplemental irrigation (SI)”.

Reply: The symbols have been added.

 

-       In lines 337: Please change “IF” to “RF”.

Reply: “IF” has been corrected, thank you.

 

 -       In lines 452: Please change “Blum also stressed--------- drought stress [49].” to “Blum [49] also stressed-----”.

Reply: We have modified it as your kind suggestion, thanks.

Reviewer 2 Report

Plant architecture influences population transpiration and canopy temperature in winter wheat genotypes

In this study, the authors tried to confirm the link between the variation of morphological traits of two winter wheat genotypes (upright-leafed compact type Jing 411 and flat-leafed loose  type Jinmai 47 ) on one hand and different aspects of which affect field performance and achieving the maximum yield with water conserving under rain-fed (RF) and supplemental irrigation (SI) conditions on the other hand.

The results indicated that Jinmai 47 was the best in everything i.e leaf net photosynthetic rate, stomatal conductance, transpiration rate, canopy temperature depression, yield and Water use efficiency (WUE) compared to the other genotype (Jing 411). Meanwhile, no difference was observed in total evapotranspiration (TET), population-scale transpiration (PT) and evapotranspiration (ET).

Unfortunately, I’m not convinced with the scientific importance of this study for different reasons:

1- The difference in the field performance between the two genotypes is self-evident. The flag leaf area of Jinmai 47 (Loose type) is higher compared to Jing 411; the compact type (Table 2). It is well known that flag leaf area is considered one of the most restricted factors to the yield of wheat crop. Therefore, it is logical to see much leaf net photosynthetic rate and stomatal conductance leading to improve the yield.

2- As well as, it is logic to see that the canopy temperature depression (CTD, ℃) was significantly increased in Jinmai 47 (Loose type) compared to Jing 411 (The compact type) under RF condition and SI condition. This response will help plants to decrease the rate of respiration and increase net photosynthesis and eventually enhance the productivity

3- The efficiency of photosynthesis and water conserving of two studied genotypes are not necessary to be related just with the morphological aspects, it may be correlated with many other factors i.e. the change in the activities of different enzymes and different metabolic and biochemical pathways.

4- In Figure 4, most of differences between the two investigated genotypes in water consumption were observed in soil evaporation (E) either under rain-fed (RF) or supplemental irrigation (SI) conditions. No significant differences were detected in the rate of transpiration between the two genotypes. Fine, it’s right low plant spacing and high densities can affect the humidity and soil evaporation. However, it remains just speculation to confirm that wheat plants with different leaf form or flag leaf inclination angle have the ability to save water differently without the observing of other factors i.e. the ratio of sclerenchyma, silica, cuticle and the activities of different enzymes 

Author Response

Reviewer 2

Plant architecture influences population transpiration and canopy temperature in winter wheat genotypes

In this study, the authors tried to confirm the link between the variation of morphological traits of two winter wheat genotypes (upright-leafed compact type Jing 411 and flat-leafed loose  type Jinmai 47 ) on one hand and different aspects of which affect field performance and achieving the maximum yield with water conserving under rain-fed (RF) and supplemental irrigation (SI) conditions on the other hand.

The results indicated that Jinmai 47 was the best in everything i.e leaf net photosynthetic rate, stomatal conductance, transpiration rate, canopy temperature depression, yield and Water use efficiency (WUE) compared to the other genotype (Jing 411). Meanwhile, no difference was observed in total evapotranspiration (TET), population-scale transpiration (PT) and evapotranspiration (ET).

Unfortunately, I’m not convinced with the scientific importance of this study for different reasons:

1- The difference in the field performance between the two genotypes is self-evident. The flag leaf area of Jinmai 47 (Loose type) is higher compared to Jing 411; the compact type (Table 2). It is well known that flag leaf area is considered one of the most restricted factors to the yield of wheat crop. Therefore, it is logical to see much leaf net photosynthetic rate and stomatal conductance leading to improve the yield.

2- As well as, it is logic to see that the canopy temperature depression (CTD, ℃) was significantly increased in Jinmai 47 (Loose type) compared to Jing 411 (The compact type) under RF condition and SI condition. This response will help plants to decrease the rate of respiration and increase net photosynthesis and eventually enhance the productivity

3- The efficiency of photosynthesis and water conserving of two studied genotypes are not necessary to be related just with the morphological aspects, it may be correlated with many other factors i.e. the change in the activities of different enzymes and different metabolic and biochemical pathways.

4- In Figure 4, most of differences between the two investigated genotypes in water consumption were observed in soil evaporation (E) either under rain-fed (RF) or supplemental irrigation (SI) conditions. No significant differences were detected in the rate of transpiration between the two genotypes. Fine, it’s right low plant spacing and high densities can affect the humidity and soil evaporation. However, it remains just speculation to confirm that wheat plants with different leaf form or flag leaf inclination angle have the ability to save water differently without the observing of other factors i.e. the ratio of sclerenchyma, silica, cuticle and the activities of different enzymes 

Reply: As known, plant architectures associate with population structure. The current study aimed at clarifying how plant architecture affects canopy traits and water use of wheat population, which might provide important information for cultivar improvement and ideal population structure establishment. So we investigated the plant architecture attributes flag leaf area, leaf inclination angle etc., transpirational physiological parameters leaf net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate (Tr), canopy traits population density (PD) and canopy temperature depression (CTD), and water use traits soil evaporation (E), population transpiration (PT), evapotranspiration for the period from jointing to early grain filling stage (ET), and total evapotranspiration for the whole growing season (TET) and yield.  

Reviewer 2 pointed out the larger flag leaf area and larger CTD all benefit photosynthetic rate and productivity. We also agree that the larger flag leaf area, the larger CTD, as well as the higher leaf photosynthetic rate could consistently explain the higher grain yield in genotype Jinmai 47. However, the higher Tr and the higher PD could not account for the similar PT, ET, and TET with genotype Jing 411. This indicated that leaf-scale transpiration may not represent population-scale transpiration which is subjected to population structure. This result highlights the importance of population structure in water saving, which we paid more attention and also stressed in Discussion.             . 

Besides, the larger CTD in Jinmai 47 conflicted with its similar population transpiration to Jing 411. Increased transpiration brought about cooler canopy temperature, namely larger CTD (See the literature 22,33,34). CTD was proved to be positively correlated with the transpiration status in wheat, rice, potatoes, and sugar beet (See the literature 35). Our study showed Jinmai 47 had been keeping higher CTD, though consumed similar PT with Jing 411.

Additionally, the rather higher yield in Jinmai 47 conflicted with its similar population transpiration to Jing 411. Transpiration is a determinant factor for yield according to the classic biomass-transpiration function (See literature 48). Blum also stressed that breeding for maximized soil moisture capture for transpiration is the most important target for yield improvement under drought stress (See literature 49). However, our study showed that Jinmai 47 consumed similar amount of water viewing from the TET, but obtained rather higher yield than Jing 411, challenging the classical transpiration-yield relation in wheat cultivars.

Based on all the conflicts described above, we stressed the dominant effect of canopy structure on water saving, and pointed out the involvement of plant architecture disrupts the original transpiration-CTD and transpiration-yield relations. The canopy structure of upright-leafed Jing 411 allowed fast exchange of water and heat between air and the canopy, then diminished CTD and enhanced PT. In comparison, canopy structure of flat-leafed Jinmai 47 prevented faster exchange of water and heat between the canopy and atmosphere, thus gained a greater CTD and inhibited PT as a result.

As for other influential factors of water use that reviewer 2 mentioned, such as sclerenchyma, silica, cuticle and different enzyme activities, we did not investigated. Instead, we determined leaf Tr, the integrative index affected by stomatal conductance and some morphological traits as reviewer 2 suggested. We think it could represent the property of leaf-scale transpiration, and thus is enough for the current study aiming at clarifying the association between canopy traits and population transpiration.

Reviewer 3 Report

Dear authors,

I like your research paper very much from my breeder stand point of view. This could be potentially very interesting to wheat breeding, as we could easily know which kind of plants to choose, if you confirmed your thesis about flat-leafed loose architecture. 

My only concern is that this research is not done on more varieties, and that you choose only to test two. If you have more varieties where you can prove your thesis please add it. If you do not have it, this needs to stated in the conclusion, as I am afraid that this is lack in this investigation.

Other comments:

-through whole manuscript better to use grain yield instead yield

-in introduction and through whole manuscript it is little bit difficult to follow text with all these abbreviations. Please try to add full words

-in introduction line 116 By selecting two genotypes contrasting in plant architectures and once widely cultivated in the NCP as commercial cultivars

-in m and m line 152 no need to use latin name of wheat again 

In results in the beginning no need to repeat what you already stated in m and m

-May you add pictures of those two genotypes that we visually can see what kind of leaves on the plants are tested? Please add this.

-line 360, in the discussion may you please add few sentences about previous result of grain yield of tested genotypes or similar, including references?

-line 403 maize instead corn

 

-don't use in brackets figures or tables in discussion

Author Response

Reviewer 3

Dear authors,

I like your research paper very much from my breeder stand point of view. This could be potentially very interesting to wheat breeding, as we could easily know which kind of plants to choose, if you confirmed your thesis about flat-leafed loose architecture. 

My only concern is that this research is not done on more varieties, and that you choose only to test two. If you have more varieties where you can prove your thesis please add it. If you do not have it, this needs to stated in the conclusion, as I am afraid that this is lack in this investigation.

Reply: We pointed out in the end of the conclusion as “It should be noted the current study was limited to only two wheat genotypes. Thus further studies remain to be carried out to confirm flat-leafed loose architecture as a potential factor for coordinately realizing the dual goal of water conserving and yield improving in wheat crops.”

 

Other comments:

 

-through whole manuscript better to use grain yield instead yield

Reply: The whole manuscript has been checked up and most of the “yield” were replaced to “grain yield”, only except “yield potential”, “yield performance”, and “transpiration-yield relation” remain unchanged, for yield indicates grain yield for cereal crops, as readers can easily understand.

-in introduction and through whole manuscript it is little bit difficult to follow text with all these abbreviations. Please try to add full words

Reply: Those less frequently used abbreviations including NCP, PD, Pn, Gs, Tr, and WU have been replaced by adding full words.

 

-in introduction line 116 By selecting two genotypes contrasting in plant architectures and once widely cultivated in the NCP as commercial cultivars

Reply: We have modified.

 

-in m and m line 152 no need to use latin name of wheat again 

Reply: We have modified.

 

In results in the beginning no need to repeat what you already stated in m and m

Reply: Meteorological conditions were not introduced in Materials and methods, but analyzed in Results. As known, water consumption (population transpiration and soil evaporation etc.) of wheat crops in the field is strongly influenced by rainfall in the growth period, which varies largely across different years. The period from jointing to early grain filling stage, the largest water requirement period for winter wheat was chosen for investigation in the current study. Analyzing the rainfall conditions especially for this period to highlight the differences helps understand yearly variation in water consumption.

 

-May you add pictures of those two genotypes that we visually can see what kind of leaves on the plants are tested? Please add this.

Reply: We did take some photos for the two wheat genotypes grown in the field, but regret the photo resolution might not meet the requirement for publication.

 

-line 360, in the discussion may you please add few sentences about previous result of grain yield of tested genotypes or similar, including references?

Reply: Jinmai 47 has been a control variety in some variety regional tests in the North China, but did not find its yield report in the research publications.  

 

-line 403 maize instead corn

Reply: Corn has been changed to maize.

 

 -don't use in brackets figures or tables in discussion

Reply: All the “in brackets figures or tables” in discussion have been deleted.

Round 2

Reviewer 2 Report

 

The authors mentioned in their reply that the higher Tr and the higher PD could not account for the similar PT, ET, and TET with genotype Jing 411

First, according to the results in Table 3,  Jinmai 47 has higher transpiration rate more than Jing 411 in the three studied seasons and under both investigated watering methods

Secondly, PT, ET (Figure 2) and TET (Figure 3) were not significantly affected in the two studied genotypes and between each other

It is obvious that specifically in Figure 2, different means (PT, E and ET) with the same latters (the same significant level) due to the increase of standard errors during the implementing of experiments and recording different data (please see the big values of standard deviation in Figure 2).

i'm still disagree with the conception of authors

Plant architecture cannot be used alone to determine the yield and tolerance of wheat crop to drought stress or deficit irrigation

Author Response

The authors mentioned in their reply that the higher Tr and the higher PD could not account for the similar PT, ET, and TET with genotype Jing 411.

Reply: Yes, we mentioned that in ABSTRACT.

 

First, according to the results in Table 3,  Jinmai 47 has higher transpiration rate more than Jing 411 in the three studied seasons and under both investigated watering methods.

Reply: Yes, it is as table 3 showed.

 

Secondly, PT, ET (Figure 2) and TET (Figure 3) were not significantly affected in the two studied genotypes and between each other.

Reply: Yes, PT, ET，and TET did not differ significantly across the two genotypes,as Fig.2 and Fig.3 showed.

 

It is obvious that specifically in Figure 2, different means (PT, E and ET) with the same latters (the same significant level) due to the increase of standard errors during the implementing of experiments and recording different data (please see the big values of standard deviation in Figure 2).

Reply: Yes. There were no significant differences in the three water use parameters among the two genotypes. The difference in their means were due to the big standard deviation generated during experiment.

 

i'm still disagree with the conception of authors.

Plant architecture cannot be used alone to determine the yield and tolerance of wheat crop to drought stress or deficit irrigation.

Reply: We don’t agree to this concept either, it has never been our concept virtually.

       Reviewer 2’s 2nd round comments right consist with some of our results and conclusions. Jinmai 47 did show higher leaf transpiration rate (Tr) (Table 3) and higher population density (PD) (Fig. 1 ) than Jing 411. Thus it should have showed higher population transpiration (PT) than Jing 411. But conversely, the three consecutive year’s experiment consistently showed the two genotypes did not differ in PT, ET and TET statistically. The different means of the three water use parameters were derived from the big standard deviation generated during experiment, as reviewer 2 pointed out and we also agree to.

        However, we disagree with reviewer 2’s conclusive comment, for our concept is not “plant architecture could be used alone to determine the yield and tolerance of wheat crop to drought stress or deficit irrigation” at all. Our study concerns effects of plant architecture on water use traits and canopy traits, rather than on yield performance. The unexpected results about the yield-PT (and TET) relation mentioned above challenged the classical saving water-losing yield concept. Besides, the similar PT also contradict with the larger CTD in Jinmai 47 comparing to Jing 411, challenging the original higher transpiration-larger CTD relation, as fully discussed in the manuscript. The two genotypes used in the study strongly contrast in plant architecture. Thus such results logically lead us to the concept that the involvement of plant architecture disrupts the original relationships between yield and water use, and between PT and CTD, based on which we pointed out that plant architecture influences population transpiration and canopy temperature.       

        Additionally, reviewer 2 questioned the statement “the higher Tr and the higher PD could not account for the similar PT, ET, and TET with genotype Jing 411”. I guess it might be the improper use of the word “account for” that makes the reviewer misunderstand the original meaning. So we have replaced this word by using “explain”.