the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Responses of field-grown maize to different soil types, water regimes, and contrasting vapor pressure deficit
Abstract. Drought is a serious constraint to crop growth and production of important staple crops such as maize. Improved understanding of the responses of crops to drought can be incorporated into cropping system models to support crop breeding, varietal selection and management decisions for minimizing negative impacts. We investigate the impacts of different soil types (stony and silty) and water regimes (irrigated and rainfed) on hydraulic linkages between soil and plant, as well as root: shoot growth characteristics. Our analysis is based on a comprehensive dataset measured along the soil-plant-atmosphere pathway at field scale in two growing seasons (2017, 2018) with contrasting climatic conditions (low and high VPD). Roots were observed mostly in the topsoil (10–20 cm) of the stony soil while more roots were found in the subsoil (60–80 cm) of the silty soil. The difference in root length was pronounced at silking and harvest between the soil types. Total root length was 2.5–6 times higher in the silty soil compared to the stony soil with the same water treatment. At silking time, the ratios of root length to shoot biomass in the rainfed plot of the silty soil (F2P2) were 3 times higher than those in the irrigated silty soil (F2P3) while the ratio was similar for two water treatments in the stony soil. With the same water treatment, the ratios of root length to shoot biomass of silty soil was higher than stony soil. The observed minimum leaf water potential (ψleaf) varied from around -1.5 MPa in the rainfed plot in 2017 to around -2.5 MPa in the same plot of the stony soil in 2018. In the rainfed plot, the mimimum ψleaf in the stony soil was lower than in silty soil from -2 to -1.5 MPa in 2017, respectively while these were from -2.5 to -2 MPa in 2018, respectively. Leaf water potential, water potential gradients from soil to plant roots, plant hydraulic conductance (Ksoil_plant), stomatal conductance, transpiration, and photosynthesis were considerably modulated by the soil water content and the conductivity of the rhizosphere. When the stony soil and silt soil are compared, the higher 'stress' due to the lower water availability in the stony soil resulted in less roots with a higher root tissue conductance in the soil with more stress. When comparing the rainfed with the irrigated plot in the silty soil, the higher stress in the rainfed soil resulted in more roots with a lower root tissue conductance in the treatment with more stress. This illustrates that the 'response' to stress can be completely opposite depending on conditions or treatments that lead to the differences in stress that are compared. To respond to water deficit, maize had higher water uptake rate per unit root length and higher root segment conductance in the stony soil than in the silty soil, while the crop reduced transpired water via reduced aboveground plant size. Future improvements of soil-crop models in simulating gas exchange and crop growth should further emphasize the role of soil textures on stomatal function, dynamic root growth, and plant hydraulic system together with aboveground leaf area adjustments.
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CC1: 'Comment on egusphere-2023-2967', Oliver Dilly, 05 Jan 2024
I suggest to delete "different soil types, " at least in the title since this is misleading with reference to soil classifcation systems.
Only two contrasting soils has been considered differing in soil texture/ stone content; little information on soil type has been given.
Citation: https://doi.org/10.5194/egusphere-2023-2967-CC1 -
AC1: 'Reply on CC1', Thuy Nguyen, 19 Feb 2024
Dear Dr. Oliver Dilly
Many thanks for your comments. We will consider and address your constructive comments after receiving all comments from editors/reviewers to improve the manuscript/
Regards
Thuy Nguyen
Citation: https://doi.org/10.5194/egusphere-2023-2967-AC1 -
AC4: 'Reply on CC1', Thuy Nguyen, 12 Apr 2024
Dear Dr. Dilly,
Thank you very much for your comments.
There were several studies have described more in detailed soil information in our study. We based on description in soil texture and particle content based on the three studies from Weihermüller et al., (2007), Stadler et al. (2015), and Morandage et al., (2021). For the field in our study, the dominant soil is a Haplic Luvisol that contains a layer with clay accumulation (silty loam texture) (Weihermüller et al., 2007). The thickness of the silty loam layer varies strongly along the slope of the field. It is up to 3 m thick at the bottom of the slope and not present at the top. One rhizotron facility is located at the top (stony) and has a stone content of >60% that this was referred to Cambisol [Geoscientific data from Geological Service North Rhine-Westphanlia, Krefeld (2012) with FAO soil taxonomy – IUSS Working Group WRB, (2006), see Fig. 1 in Stadler et al., (2015) and Table 1 in Morandage et al., (2021)]. The second rhizotron facility is located at the bottom of slope. It has a thick layer with silty loam and a negligible stone content (<4%) which is described as “stagnic Luvisol” [Geoscientific data from Geological Service North Rhine-Westphanlia, Krefeld (2012) with FAO soil taxonomy – IUSS Working Group WRB, (2006), see Fig. 1 in Stadler et al., (2015) and Table 1 in Morandage et al., (2021)]. This is a reason that we used the different soil types. We listed those three references the MS for the readers to have extra information with regards of soil types.
References:
Morandage, S., J. Vanderborght, M. Zörner, G. Cai, D. Leitner, et al. 2021. Root architecture development in stony soils. Vadose Zo. J. (April): 1–17. doi: 10.1002/vzj2.20133.
Weihermüller, L., Huisman, J. A., Lambot, S., Herbst, M., & Vereecken, H. (2007). Mapping the spatial variation of soil water content at the field scale with different ground penetrating radar techniques. Journal of Hydrology, 340, 205–216. https://doi.org/10.1016/j.jhydrol.2007. 04.013
Geological Service North Rhine-Westphalia, 2012 Geological Service North Rhine-Westphalia-GD.NRW (2012), Soil Map of North Rhine-Westphalia 1:5000, Procedure LA003 ‘Aldenhoven’ (1969/2008) and Procedure W9506 ‘Ellen, WSG’ (1984/1996).
Stadler, A., Rudolph, S., Kupisch, M., Langensiepen, M., Van Der Kruk, J., & Ewert, F. (2015). Quantifying the effects of soil variability on crop growth using apparent soil electrical conductivity measurements. European Journal of Agronomy, 64, 8–20. https://doi.org/10.1016/j. eja.2014.12.004
Citation: https://doi.org/10.5194/egusphere-2023-2967-AC4
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AC1: 'Reply on CC1', Thuy Nguyen, 19 Feb 2024
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RC1: 'Comment on egusphere-2023-2967', Jos C. van Dam, 13 Mar 2024
General comments
The authors performed an extensive study on maize growth at two distinct soil textures with different water regimes for a normal and extremely dry weather year. During the growing season, they collected a comprehensive dataset on root length, soil water potential, sap flow, leaf water potential, leaf transpiration, stomatal conductance, net photosynthesis and maize growth observations. These data were used to derive hydraulic conductances for the soil-root system, the plant stems and the entire plant system, to describe the maize reaction to dry weather and soil conditions and the determine the maize water use efficiency.
The paper addresses very relevant scientific questions related to the growth and management of one of the most important staple crops. The methods are clearly described and valid. The experimental results are well presented in 14 informative graphs and supplementary material and are objectively in detail described. The discussion is systematic and justified. Both the introduction and discussion are embedded in current scientific literature. The conclusions are sound and very useful for state-of-the-art crop-soil modeling.
In general, the used language is fluent and precise. Below I listed some minor text errors.
Specific comments
Line 66: Omit “of”
Line 117: Add space in “genotypesduring”
Line 134: “it” should be “it’s”
Line 178: “and 2018F1P3” should be “and 2018F2P3”
Line 180: omit “in”
Line 187: “form” should be “from”
Line 593-596: rewrite sentence
Line 649: “effects” should be “effect”
Line 650: “which based” should be “which was based”
Line 667-669: rewrite sentence
Citation: https://doi.org/10.5194/egusphere-2023-2967-RC1 -
AC2: 'Reply on RC1', Thuy Nguyen, 12 Apr 2024
Dear Dr. van Dam,
Thank you very much for your constructive comments and advice that will help to improve the manuscript and the study. Please kindly follow the point-to-point responses (in blue color) to your comments (in black color) below in the Supplement file. Since the revised MS was not prepared at this stage, the referred line numbers here were from the originally submitted MS. All detailed changes and revision were listed here.
On behalf of the authors
Thuy Nguyen
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AC2: 'Reply on RC1', Thuy Nguyen, 12 Apr 2024
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RC2: 'Comment on egusphere-2023-2967', Anonymous Referee #2, 27 Mar 2024
Review of the paper « Responses of field-grown maize to different soil types, water regimes, and contrasting vapor pressure deficit «
The paper reports the results of two experiments in which a maize genotype is grown under two soil types, i.e. a stony soil type and a silty soil type, and under two water treatment, i.e. a rainfed treatment that suffers water stress and a fully irrigated treatment. The authors then perform a number of measurement on the stomatal conductance, transpiration, sap flow rate, and assimilation rate, together with a number of water potential measurements at different levels. They also measured the root:shoot ratio in this factorial. One of the important results is the large variation between soil, but also between water treatment, in the root:shoot ratio. This has consequences for the hydraulic conductance of the soil-root-leaf-atmosphere continuum, where the main result is the demonstration that root system and soil-plant hydraulic conductance depended strongly on the soil texture. This is an important result that confirms other recent findings.
The results of the paper are very important, especially in showing the important role of the soil in shaping up plant physiological responses related to the plant hydraulic properties, and as such need to be published. That said, I find that the paper is quite long and with too many figures (14). It has a discussion that I think is too long (11 pages) and contains complex elements of the results and does not make enough effort of summarizing, part by part, what are the key messages that need to come up. Therefore, I think the papers needs to be made more concise, may be less technical in some parts of it, before it can be published. It gives at times the impression that it was written as a long report about a series of results, lacking in focus sometimes. As it stands, it does not pay justice to the results that are presented and to the work that was done.
Minor comments:
L108: Replace ‘that’ by ‘because they’
L117: Space
L128: Insert ‘.’ After ‘conductance’
L134: replace ‘it’ by ‘its’
L138: replace ‘includes’ by ‘including’
L146-147: may be replace ‘different components (root, stem and whole soil-plant hydraulic conductance)’ by ‘different components of the hydraulic conductance (root, stem, whole soil-plant)’
L155-157: Does each of these “rhizitrone facilities” represent what you call later “a site”??
L187: replace ‘form’ by ‘from’
L198: Do you mean to say that over the 7m length of each of these 54 horizontal tubes, 20 measurements (images) were taken in each of them??
L206: replace ’of’ by ‘in’
L210-211: Do you mean to say that you harvested five subplots, each of a 1m2, in each replication?? If that is the case, how did you treat the data? You averaged them?
L304-305: The question is whether you measured such root cracks. And also what was the size of these putative crack as, if too large, roots may not be able to grow through such air-filled gaps. So, may be clarify whether you had any kind of indication of such cracks, and about their size (in Vertisol you could have cracks that would be 10 cm wide and surely no roots would go through that, so, it is important to know more about soil cracks in that silty soil).
L312-328 and Figs 4-6: I wonder if you should group the three figures by showing the continuation of these 4 types of measurements on the same graph, indicating when irrigation would begin and stop. It would much better allow to compare different days, and compare soil and soil-by-water treatment combinations among them for these different factors. The way the figures are laid out and given the relatively small differences it is a bit difficult to do that.
L377-378: Here you switch to DOY, whereas in earlier figures you used the calendar dates. This may be a detail but the data presented are sufficiently complex that it would be good to harmonize what can be. So either choose DOY or calendar dates but stick to it.
L389-399: I see the graph of Fig 11, but the end of the paragraph makes an important interpretation on the data that I have difficulties to follow, possibly because the data that are presented are not adequate for the reader to easily understand that interpretation. Could you clarify?
L440: Instead of saying that rooting depth was sensitive to the presence of crack, it would be clearer to say if presence of cracks increased/decreased rooting depth.
L455: you mention root:shoot ratio but then talk about 200-1000 cmg-1, which is a density and not a ratio, please correct.
L435-478: This part of the discussion is too long, repeats a number of result part, and then brings elements of literature in a rather scattered and unrelated way (for instance talking about the soil nutrient effects on root length). And finally, it does not give a tangible conclusion of what we should retain about these root length differences between soil texture and between water treatment.
L481: as affected by ?
L484: replace ‘lower’ by ‘less’
L482-489: you comment your results, then earlier results from others. And these are different. But you leave the reader hanging here: what is your interpretation/explanation for that?
L482-522: Here also is a fairly long piece of complex discussion that would need to end with a kind of message. I guess the message is that while Welcker and other have show genotypic differences earlier, here you show the soil influence on minimum psi Leaf.
L525: Stomatal conductance?
L528: replace ‘estimate’ by ‘estimation’
L533-539: Here I think it would be better to stick to the units of mm h-1 MPa-1 and then convert the values in 10-5 h-1 from the citations into that mm h-1 MPa-1 unit which has been used in your graphs.
L540-541: That sentence is not understandable
L649: contrasting
L666: …. and decreased at more negative…
L667: remove ‘plant’
L668: replace ‘that’ by ‘and’
Citation: https://doi.org/10.5194/egusphere-2023-2967-RC2 -
AC3: 'Reply on RC2', Thuy Nguyen, 12 Apr 2024
Dear Referee#2,
Thank you very much for your constructive comments and advice that will help to improve the manuscript
and the study. Please kindly follow the point-to-point responses (in blue color) to your comments (in black
color) below in the Supplement. Since the revised MS was not prepared at this stage, the referred line numbers here were
from the originally submitted MS. All detailed changes and revision were listed here.
On behalf of the authors
Thuy Nguyen
-
AC3: 'Reply on RC2', Thuy Nguyen, 12 Apr 2024
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