scholarly journals Whole‐plant optimality predicts changes in leaf nitrogen under variable CO 2 and nutrient availability

2019 ◽  
Vol 225 (6) ◽  
pp. 2331-2346 ◽  
Author(s):  
Silvia Caldararu ◽  
Tea Thum ◽  
Lin Yu ◽  
Sönke Zaehle
2012 ◽  
Vol 160 (3) ◽  
pp. 1479-1490 ◽  
Author(s):  
Delphine Moreau ◽  
Vincent Allard ◽  
Oorbessy Gaju ◽  
Jacques Le Gouis ◽  
M. John Foulkes ◽  
...  

Botany ◽  
2009 ◽  
Vol 87 (2) ◽  
pp. 195-201 ◽  
Author(s):  
Jitka Klimešová ◽  
Adéla Pokorná ◽  
Leoš Klimeš

Plant establishment is a risky phase of the plant life cycle because juvenile individuals cannot produce seeds and their vegetative regeneration is constrained by a lack of reserve meristems and carbon storage. On the other hand, conditions in the period following establishment, during establishment growth, affect the vegetative regeneration and clonal growth of the plant in the future. Bud-bank formation was studied in a root-sprouting clonal herb Epilobium angustifolium  L. (= Chamaenerion angustifolium (L.) Scop.), a plant with root buds differing in size and number of leaf primordia, during establishment growth. We tested two hypotheses: (i) large and small buds differ in their response to stress and disturbance, and (ii) a heterogeneous soil environment does not affect bud-bank formation. We rejected both hypotheses because (i) the proportion of small buds was about 80% and was not affected by nutrient availability and substrate heterogeneity, and (ii) plants produced more buds per root biomass under conditions of nutrient shortage in both homogeneous and heterogeneous substrates, but the effect was masked by lower root biomass. Thus, bud production for the whole plant was not affected by either nutrient availability or soil heterogeneity and reached 20 to 100 buds per plant.


1988 ◽  
Vol 15 (2) ◽  
pp. 63 ◽  
Author(s):  
TJ Givnish

Whole-plant energy capture depends not only on the photosynthetic response of individual leaves, but also on their integration into an effective canopy, and on the costs of producing and maintaining their photosynthetic capacity. This paper explores adaptation to irradiance level in this context, focusing on traits whose significance would be elusive if considered in terms of their impact at the leaf level alone. I review traditional approaches used to demonstrate or suggest adaptation to irradiance level, and outline three energetic tradeoffs likely to shape such adaptation, involving the economics of gas exchange, support, and biotic interactions. Recent models using these tradeoffs to account for trends in leaf nitrogen content, stornatal conductance, phyllotaxis, and defensive allocations in sun v. shade are evaluated. A re-evaluation of the classic study of acclimation of the photosynthetic light response in Atriplex, crucial to interpreting adaptation to irradiance in many traits, shows that it does not completely support the central dogma of adaptation to sun v. shade unless the results are analysed in terms of whole-plant energy capture. Calculations for Liriodendron show that the traditional light compensation point has little meaning for net carbon gain, and that the effective compensation point is profoundly influenced by the costs of night leaf respiration, leaf construction, and the construction of associated support and root tissue. The costs of support tissue are especially important, raising the effective compensation point by 140 �mol m-2 s-1 in trees 1 m tall, and by nearly 1350 �mol m-2 s-1 in trees 30 m tall. Effective compensation points give maximum tree heights as a function of irradiance, and shade tolerance as a function of tree height; calculations of maximum permissible height in Liriodendron correspond roughly with the height of the tallest known individual. Finally, new models for the evolution of canopy width/height ratio in response to irradiance and coverage within a tree stratum, and for the evolution of mottled leaves as a defensive measure in understory herbs, are outlined.


2015 ◽  
Vol 42 (7) ◽  
pp. 620 ◽  
Author(s):  
Frederik Wegener ◽  
Wolfram Beyschlag ◽  
Christiane Werner

Organs of C3 plants differ in their C isotopic signature (δ13C). In general, leaves are 13C-depleted relative to other organs. To investigate the development of spatial δ13C patterns, we induced different C allocation strategies by reducing light and nutrient availability for 12 months in the Mediterranean shrub Halimium halimifolium L. We measured morphological and physiological traits and the spatial δ13C variation among seven tissue classes during the experiment. A reduction of light (Low-L treatment) increased aboveground C allocation, plant height and specific leaf area. Reduced nutrient availability (Low-N treatment) enhanced C allocation into fine roots and reduced the spatial δ13C variation. In contrast, control and Low-L plants with high C allocation in new leaves showed a high δ13C variation within the plant (up to 2.5‰). The spatial δ13C variation was significantly correlated with the proportion of second-generation leaves from whole-plant biomass (R2 = 0.46). According to our results, isotope fractionation in dark respiration can influence the C isotope composition of plant tissues but cannot explain the entire spatial pattern seen. Our study indicates a foliar depletion in 13C during leaf development combined with export of relatively 13C-enriched C by mature source leaves as an important reason for the observed spatial δ13C pattern.


2019 ◽  
Author(s):  
Silvia Caldararu ◽  
Tea Thum ◽  
Lin Yu ◽  
Sönke Zaehle

SummaryVegetation nutrient limitation is essential for understanding ecosystem responses to global change. In particular, leaf nitrogen (N) is known to be plastic under changed nutrient limitation. However, models can often not capture these observed changes, leading to erroneous predictions of whole-ecosystem stocks and fluxes.We hypothesise that an optimality approach can improve representation of leaf N content compared to existing empirical approaches. Unlike previous optimality-based approaches, which adjust foliar N concentrations based on canopy carbon export, we use a maximisation criteria based on whole-plant growth and allow for a lagged response of foliar N to this maximisation criterion to account for the limited plasticity of this plant trait. We test these model variants at a range of Free-Air CO2 Enrichment (FACE) and N fertilisation experimental sites.We show a model solely based on canopy carbon export fails to reproduce observed patterns and predicts decreasing leaf N content with increased N availability. However, an optimal model which maximises total plant growth can correctly reproduce the observed patterns.The optimality model we present here is a whole-plant approach which reproduces biologically realistic changes in leaf N and can thereby improve ecosystem-level predictions under transient conditions.


2005 ◽  
Vol 66 (2) ◽  
pp. 215-221 ◽  
Author(s):  
Dugald C. Close ◽  
Clare McArthur ◽  
Ann E. Hagerman ◽  
Hugh Fitzgerald

Agronomy ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1739
Author(s):  
Kaocheng Zhao ◽  
Ying Ye ◽  
Jun Ma ◽  
Lifen Huang ◽  
Hengyang Zhuang

We aimed to elucidate the color changes of rice leaves after anthesis and create an algorithm for monitoring the nitrogen contents of rice leaves and of the whole plant. Hence, we aimed to provide a theoretical basis for the precise management of rice nitrogen fertilizer and the research and development of digital image nutrition monitoring equipment and reference. We selected the leaf colors of the main stems of four major rice varieties promoted in production, including Huaidao 5 (late-maturing medium japonica rice), Yangjing 4227 (early maturing late japonica rice), Changyou 5 (late japonica hybrid rice), and Yongyou 8 (late japonica hybrid rice). Under different nitrogen levels, the leaf R, G, and B values of the four rice varieties at different stages after anthesis, the dynamic changes in RGB normalized values, the correlations between RGB normalized values and leaf SPAD values, the leaf nitrogen content and whole plant nitrogen content, and the nitrogen prediction model were studied. The research results demonstrate the following: (1) regardless of nitrogen levels, the leaf of R, G, B, NRI, NGI and NBI of different rice varieties after anthesis followed the order, G > R > B. R, G, NRI, NGI, and days after heading could be fitted according to a logarithmic equation, y = aebx (0.726 ≤ R2 ≤ 0.992); B, NBI, and days after heading could be fitted using a linear equation, y = a + bx (0.863 ≤ R2 ≤ 0.992). Both fitting effects were significant (except NGI). (2) A quadratic function (Y = −1296.192x2 + 539.419x − 10.914; Y = −1173.104x2 + 527.073x − 12.993) was adopted to construct a monitoring model for the NBI and SPAD values of japonica rice and hybrid japonica rice leaves after anthesis and the R2 values were 0.902 and 0.838, respectively. Exponential functions (Y = 5.698e7.261x; Y = 3.371e9.326x) were employed to construct monitoring models of leaf nitrogen content, and the R2 values were 0.833 and 0.706, respectively. Exponential functions (Y = 5.145e4.9143x; Y = 3.966e5.364x) were also used to construct a monitoring model for the nitrogen content of the whole plant, and the R2 values were 0.737 and 0.511, respectively. The results obtained from prediction tests by using Determination Coefficient (R2), Relative Percent Deviation (RPD), and Root Mean Square Error (RMSE) showed that it was feasible, accurate, and efficient to use a scanner for measuring the nitrogen content of rice.


2018 ◽  
Vol 285 (1886) ◽  
pp. 20180699 ◽  
Author(s):  
Peng Wang ◽  
Yan Yang ◽  
Pu Mou ◽  
Qingzhou Zhao ◽  
Yunbin Li

Plants are thought to be able to regulate local root growth according to its overall nutrient status as well as nutrient contents in a local substrate patch. Therefore, root plastic responses to environmental changes are probably co-determined by local responses of root modules and systematic control of the whole plant. Recent studies showed that the contrast in nutrient availability between different patches could significantly influence the growth and death of local roots. In this study, we further explored, beside nutrient contrast, whether root growth and death in a local patch are also affected by relative root quantity in the patch. We conducted a split-root experiment with different splitting ratios of roots of Canada goldenrod ( Solidago canadensis ) individuals, as well as high- (5× Hoagland solution versus water) or low- (1× Hoagland solution versus water) contrast nutrient conditions for the split roots. The results showed that root growth decreased in nutrient-rich patches but increased in nutrient-poor patches when more roots co-occurred in the same patches, irrespective of nutrient contrast condition. Root mortality depended on contrasts in both root quantity and nutrients: in the high-nutrient-contrast condition, it increased in nutrient-rich patches but decreased in nutrient-poor patches with increasing root proportion; while in the low-nutrient-contrast condition, it showed the opposite trend. These results demonstrated that root growth and death dynamics were affected by the contrast in both nutrient availability and root quantity between patches. Our study provided ecological evidence that local root growth and death are mediated by both the responses of root modules to a nutrient patch and the whole-plant nutrient status, suggesting that future work investigating root production and turnover should take into account the degree of heterogeneity in nutrient and root distribution.


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