scholarly journals Adaptation to Sun and Shade: a Whole-Plant Perspective

1988 ◽  
Vol 15 (2) ◽  
pp. 63 ◽  
Author(s):  
TJ Givnish
Keyword(s):  
Biotic Interactions ◽  
Tree Height ◽  
Light Response ◽  
Leaf Nitrogen ◽  
Compensation Point ◽  
Carbon Gain ◽  
Leaf Nitrogen Content ◽  
Energy Capture ◽  
Irradiance Level ◽  
Whole Plant

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.

Repair of severe winter xylem embolism supports summer water transport and carbon gain in flagged crowns of the subalpine conifer Abies veitchii

2019 ◽  
Vol 39 (10) ◽  
pp. 1725-1735 ◽  
Author(s):  
Mayumi Y Ogasa ◽  
Haruhiko Taneda ◽  
Hiroki Ooeda ◽  
Akihiro Ohtsuka ◽  
Emiko Maruta
Keyword(s):  
Leaf Nitrogen ◽  
Carbon Gain ◽  
Late Winter ◽  
Leaf Nitrogen Content ◽  
Xylem Embolism ◽  
Coniferous Species ◽  
Abies Veitchii ◽  
Individual Level ◽  
Use Efficiency ◽  
The Individual

Abstract Xylem embolism induced by winter drought is a serious dysfunction in evergreen conifers growing at wind-exposed sites in the mountains. Some coniferous species can recover from winter embolism. The aim of this study was to determine whether wind direction influences embolism formation and/or repair dynamics on short windward and long leeward branches of asymmetrical `flagged' crowns. We analyzed the effect of branch orientation on percentage loss of xylem conductive area (PLC), leaf functional traits and the xylem:leaf area ratio for subalpine, wind-exposed flagged-crown Abies veitchii trees in the northern Yatsugatake Mountains of central Japan. In late winter, the shoot water potential was below −2.5 MPa, and the PLC exceeded 80% in 2-year-old branches, independent of branch orientation within a flagged crown. Both of these parameters almost fully recovered by summer. At branch internodes 4 years of age and older, seasonal changes in PLC were not found in either windward or leeward branches, but the PLC was higher in less leafy windward branches. The leaf nitrogen content and water-use efficiency of mature leaves were comparable between windward branches and leafy leeward branches. The ratio of xylem conductive area to total leaf area was the same for windward and leeward branches. These results indicate that the repair of winter xylem embolism allows leaf physiological functions to be maintained under sufficient leaf water supply, even on winter-wind-exposed branches. This permits substantial photosynthetic carbon gain during the following growing season on both windward and leeward branches. Thus, xylem recovery from winter embolism is a key trait for the survival of harsh winters and to support productivity on the individual level in flagged-crown A. veitchii trees.

Photosynthesis - stomatal conductance model LEAFC3-N: specification for barley, generalised nitrogen relations, and aspects of model application

2008 ◽  
Vol 35 (10) ◽  
pp. 797 ◽  
Author(s):  
Johannes Müller ◽  
Henning Braune ◽  
Wulf Diepenbrock
Keyword(s):  
Stomatal Conductance ◽  
Growth Models ◽  
Leaf Nitrogen ◽  
Carbon Gain ◽  
Model Parameters ◽  
Leaf Nitrogen Content ◽  
Time Step ◽  
Close Range ◽  
Crop Growth Models ◽  
Parameter Values

We discuss a generalised formulation of the nitrogen-sensitive photosynthesis−stomatal conductance model LEAFC3-N to be used as a submodel of functional–structural plant models (FSPMs) or traditional crop growth models for C3-crops. Based on a parameterisation study for barley, we demonstrate that the large variation of characteristics related to potential leaf photosynthesis and stomatal conductance, along with different factors, can be accounted for by introducing functions that relate parameter values to nitrogen contents. These relationships follow the same pattern for different C3 crops, and their parameters are in close range. The accuracy of the parameters and the minimum simulation time step required for reliable predictions of the integrated diurnal carbon gain (IDC) is assessed. For IDC predictions with an accuracy of about ±5%, the accuracy of the slope of the relationship between maximum carboxylation rate and leaf nitrogen content should be of similar order. For other key model parameters, an error of ±20% or even greater may be tolerated. A time step of 1–2 h will be sufficient to predict IDC with an accuracy of about ±5%.

scholarly journals Detection and Dynamic Variation Characteristics of Rice Nitrogen Status after Anthesis Based on the RGB Color Index

Agronomy ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1739
Author(s):  
Kaocheng Zhao ◽  
Ying Ye ◽  
Jun Ma ◽  
Lifen Huang ◽  
Hengyang Zhuang
Keyword(s):  
Nitrogen Content ◽  
Hybrid Rice ◽  
Leaf Nitrogen ◽  
Leaf Nitrogen Content ◽  
Japonica Rice ◽  
Rice Varieties ◽  
Nitrogen Levels ◽  
Monitoring Model ◽  
Whole Plant ◽  
Rice Leaves

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.

scholarly journals Fertilization of Young `Hamlin' Orange Trees with Controlled-release Fertilizer

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 774A-774
Author(s):  
J.J. Ferguson ◽  
F.S. Davies
Keyword(s):  
Controlled Release ◽  
Tree Height ◽  
Leaf Nitrogen ◽  
N Fertilizer ◽  
Water Soluble ◽  
Slight Reduction ◽  
Leaf Nitrogen Content ◽  
Controlled Release Fertilizer ◽  
Trunk Diameter ◽  
Orange Trees

Young `Hamlin' orange trees [Citrus sinensis (L.) Osbeck] were fertilized six times/year with water-soluble N fertilizer at recommended rates (0.20, 0.34, and 0.38 kg N/tree per year) and with controlled-release fertilizer one time/year [Osmocote, IDBU, and a 44.5% urea-N fertilizer coated with a sulfonated ethylene-propylene-diene polymer (Sherritt, Inc.)] at 0.04, 0.06, and 0.08 kg N/tree per year for years 1, 2, and 3, respectively. There were no differences in trunk diameter, tree height, or tree rating among treatments in any year, although there was a slight reduction in tree rating for some trees with biuret symptoms in the Sherritt treatment in year 2. Leaf nitrogen content was acceptable for all treatments in all 3 years, except for the Osmocote treatment in year 2, which had low to deficient levels. Levels of other nutrients were all within acceptable ranges, except for low potassium levels for the Osmocote in year 2. There were no significant differences in yields of young trees in year 3, the first bearing year. Given its 44.5% N analysis, the total amount of Sherritt controlled-release fertilizer applied to young citrus trees was 4% that of the standard, water-soluble fertilizer and from 39% to 45% that of the two other controlled-release fertilizers in years 1, 2, and 3.

scholarly journals Estimating the Leaf Nitrogen Content with a New Feature Extracted from the Ultra-High Spectral and Spatial Resolution Images in Wheat

2021 ◽  
Vol 13 (4) ◽  
pp. 739
Author(s):  
Jiale Jiang ◽  
Jie Zhu ◽  
Xue Wang ◽  
Tao Cheng ◽  
Yongchao Tian ◽  
...  
Keyword(s):  
Nitrogen Content ◽  
Precision Agriculture ◽  
Field Experiments ◽  
Mean Squared Error ◽  
Growing Season ◽  
Leaf Nitrogen ◽  
Textural Analysis ◽  
Hyperspectral Images ◽  
Leaf Nitrogen Content ◽  
New Feature

Real-time and accurate monitoring of nitrogen content in crops is crucial for precision agriculture. Proximal sensing is the most common technique for monitoring crop traits, but it is often influenced by soil background and shadow effects. However, few studies have investigated the classification of different components of crop canopy, and the performance of spectral and textural indices from different components on estimating leaf nitrogen content (LNC) of wheat remains unexplored. This study aims to investigate a new feature extracted from near-ground hyperspectral imaging data to estimate precisely the LNC of wheat. In field experiments conducted over two years, we collected hyperspectral images at different rates of nitrogen and planting densities for several varieties of wheat throughout the growing season. We used traditional methods of classification (one unsupervised and one supervised method), spectral analysis (SA), textural analysis (TA), and integrated spectral and textural analysis (S-TA) to classify the images obtained as those of soil, panicles, sunlit leaves (SL), and shadowed leaves (SHL). The results show that the S-TA can provide a reasonable compromise between accuracy and efficiency (overall accuracy = 97.8%, Kappa coefficient = 0.971, and run time = 14 min), so the comparative results from S-TA were used to generate four target objects: the whole image (WI), all leaves (AL), SL, and SHL. Then, those objects were used to determine the relationships between the LNC and three types of indices: spectral indices (SIs), textural indices (TIs), and spectral and textural indices (STIs). All AL-derived indices achieved more stable relationships with the LNC than the WI-, SL-, and SHL-derived indices, and the AL-derived STI was the best index for estimating the LNC in terms of both calibration (Rc2 = 0.78, relative root mean-squared error (RRMSEc) = 13.5%) and validation (Rv2 = 0.83, RRMSEv = 10.9%). It suggests that extracting the spectral and textural features of all leaves from near-ground hyperspectral images can precisely estimate the LNC of wheat throughout the growing season. The workflow is promising for the LNC estimation of other crops and could be helpful for precision agriculture.

scholarly journals Leaf traits and gas exchange in saplings of native tree species in the Central Amazon

2010 ◽  
Vol 67 (6) ◽  
pp. 624-632 ◽  
Author(s):  
Keila Rego Mendes ◽  
Ricardo Antonio Marenco
Keyword(s):  
Gas Exchange ◽  
Nitrogen Content ◽  
Leaf Area ◽  
Tree Species ◽  
Leaf Traits ◽  
Leaf Nitrogen ◽  
Dry Season ◽  
Leaf Thickness ◽  
Rainfall Regime ◽  
Leaf Nitrogen Content

Global climate models predict changes on the length of the dry season in the Amazon which may affect tree physiology. The aims of this work were to determine the effect of the rainfall regime and fraction of sky visible (FSV) at the forest understory on leaf traits and gas exchange of ten rainforest tree species in the Central Amazon, Brazil. We also examined the relationship between specific leaf area (SLA), leaf thickness (LT), and leaf nitrogen content on photosynthetic parameters. Data were collected in January (rainy season) and August (dry season) of 2008. A diurnal pattern was observed for light saturated photosynthesis (Amax) and stomatal conductance (g s), and irrespective of species, Amax was lower in the dry season. However, no effect of the rainfall regime was observed on g s nor on the photosynthetic capacity (Apot, measured at saturating [CO2]). Apot and leaf thickness increased with FSV, the converse was true for the FSV-SLA relationship. Also, a positive relationship was observed between Apot per unit leaf area and leaf nitrogen content, and between Apot per unit mass and SLA. Although the rainfall regime only slightly affects soil moisture, photosynthetic traits seem to be responsive to rainfall-related environmental factors, which eventually lead to an effect on Amax. Finally, we report that little variation in FSV seems to affect leaf physiology (Apot) and leaf anatomy (leaf thickness).

Sign in / Sign up

Export Citation Format

Share Document