Seasonal stability of chlorophyll fluorescence quantified from airborne hyperspectral imagery as an indicator of net photosynthesis in the context of precision agriculture

2016 ◽  
Vol 179 ◽  
pp. 89-103 ◽  
Author(s):  
P.J. Zarco-Tejada ◽  
M.V. González-Dugo ◽  
E. Fereres
Keyword(s):  
Chlorophyll Fluorescence ◽  
Precision Agriculture ◽  
Hyperspectral Imagery ◽  
Net Photosynthesis

Selection of tree species for forests under climate change: is PSI functioning a better predictor for net photosynthesis and growth than PSII?

2020 ◽  
Vol 40 (11) ◽  
pp. 1561-1571 ◽  
Author(s):  
Martina Pollastrini ◽  
Elisabetta Salvatori ◽  
Lina Fusaro ◽  
Fausto Manes ◽  
Riccardo Marzuoli ◽  
...  
Keyword(s):  
Climate Change ◽  
Chlorophyll Fluorescence ◽  
Tree Species ◽  
Leaf Gas Exchange ◽  
Central Italy ◽  
Common Garden ◽  
Net Photosynthesis ◽  
Photosynthetic Performance ◽  
Seasonal Temperature

Abstract A chlorophyll fluorescence (ChlF) assessment was carried out on oak seedlings (Quercus ilex L., Quercus pubescens Willd., Quercus frainetto Ten.) of Italian and Greek provenance, during the years 2017 and 2018, in a common garden in central Italy planted in 2017. This trial aimed to test the relative performances of the oak species in the perspective of assisted migration as part of the actions for the adaptation of forests to climate change. The assessment of the photosynthetic performance of the tree species included the analysis of the prompt chlorophyll fluorescence (PF) transient and the modulated reflection (MR) at 820 nm, leaf chlorophyll content, leaf gas exchange (net photosynthesis, stomatal conductance), plant growth (i.e., height) and mortality rate after 2 years from the beginning of the experiment. The assessment of the performance of the three oak species was carried out ‘in vivo’. Plants were generated from seeds and exposed to several environmental factors, including changing seasonal temperature, water availability, and soil biological and physical functionality. The results of PF indicate a stable functionality of the photosynthetic system PSII (expressed as FV/FM) across species and provenances and a decline in photochemistry functionality at the I–P phase (ΔVIP) in Q. frainetto, thus indicating a decline of the content of PSI in this species. This result was confirmed by the findings of MR analysis, with the speed of reduction and subsequent oxidation of PSI (VRED and VOX) strongly correlated to the amplitude of ΔVIP. The photosynthetic rates (net photosynthesis, PN) and growth were correlated with the parameters associated with PSI content and function, rather than those related to PSII. The low performance of Q. frainetto in the common garden seems to be related to early foliar senescence with the depletion of nitrogen, due to suboptimal climatic and edaphic conditions. Chlorophyll fluorescence allowed discrimination of populations of oak species and individuation of the less (or/and best) suitable species for future forest ecology and management purposes.

Effects of drought on photosynthesis in grapevines under field conditions: an evaluation of stomatal and mesophyll limitations

2002 ◽  
Vol 29 (4) ◽  
pp. 461 ◽  
Author(s):  
Jaume Flexas ◽  
Josefina Bota ◽  
José M. Escalona ◽  
Bartolomé Sampol ◽  
Hipólito Medrano
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport Rate ◽  
Net Photosynthesis ◽  
Co2 Concentration ◽  
Vitis Vinifera L ◽  
Severe Drought ◽  
Mesophyll Conductance ◽  
Progressive Decline ◽  
Effects Of Drought ◽  
Combined Measurements

The effect of diffusional and photochemical limitations to photosynthesis was assessed in field-grown water-stressed grapevines (Vitis vinifera L.) by combined measurements of gas exchange and chlorophyll fluorescence. Drought was slowly induced, and the progressive decline of photosynthesis was examined in different grapevine cultivars along a continuous gradient of maximum mid-morning values of stomatal conductance (g), which were used as an integrative indicator of the water-stress conditions endured by the leaves. Initial decreases of g were accompanied by decreases of substomatal CO2 concentration (Ci), the estimated chloroplastic CO2 concentration (Cc) and net photosynthesis (AN), while electron transport rate (ETR) remained unaffected. With increasing drought, g, AN, Ci and Cc further decreased, accompanied by slight decreases of ETR and of the estimated mesophyll conductance (gmes). Severe drought led to strong reductions of both g and gmes, as well as of ETR. The apparent carboxylation efficiency and the compensation point for CO2 remained unchanged under severe drought when analysed on a Cc, rather than a Ci, basis, suggesting that previously reported metabolic impairment was probably due to decreased gmes.

scholarly journals Copper Stress on Photosynthesis of Black Mangle (Avicennia germinans)

2013 ◽  
Vol 85 (2) ◽  
pp. 665-670 ◽  
Author(s):  
DANIEL GONZALEZ-MENDOZA ◽  
FRANCISCO ESPADAS y GIL ◽  
FERNANDO ESCOBOZA-GARCIA ◽  
JORGE M. SANTAMARIA ◽  
OMAR ZAPATA-PEREZ
Keyword(s):  
Chlorophyll Fluorescence ◽  
Photosynthetic Apparatus ◽  
Copper Toxicity ◽  
Net Photosynthesis ◽  
Avicennia Germinans ◽  
Copper Stress ◽  
Photosynthetic Gas Exchange ◽  
Chlorophyll Fluorescence Parameters ◽  
Fluorescence Parameters ◽  
Photosynthetic Activities

The effects of copper toxicity on the photosynthetic activities of Avicennia germinans was investigated using two CuSO4 concentrations (0.062 and 0.33 M) added in Hoagland's solution in an aerated hydroponic system. Photosynthesis and chlorophyll fluorescence were measured after 30 h of copper stress. Results obtained in this study show that increasing levels of Cu+2 of 0.062 and 0.33 M Cu+2 resulted in a general reduction of the stomatal conductance (28 and 18%, respectively) and 100% of inhibition of net photosynthesis. Additionally, at these concentrations of Cu+2, reductions of chlorophyll fluorescence parameters were also observed. These changes suggested that the photosynthetic apparatus of Avicennia germinans was the primary target of the Cu+2 action. It is concluded that Cu+2 ions causes a drastic decline in photosynthetic gas exchange and Chlorophyll fluorescence parameters in A. germinans leaves.

scholarly journals Evaluating the predictive power of sun-induced chlorophyll fluorescence to estimate net photosynthesis of vegetation canopies: A SCOPE modeling study

2016 ◽  
Vol 176 ◽  
pp. 139-151 ◽  
Author(s):  
Jochem Verrelst ◽  
Christiaan van der Tol ◽  
Federico Magnani ◽  
Neus Sabater ◽  
Juan Pablo Rivera ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Predictive Power ◽  
Net Photosynthesis ◽  
Vegetation Canopies ◽  
Modeling Study

scholarly journals Carbohydrate Injections as a Potential Option to Improve Growth and Vitality of Live Oaks

2009 ◽  
Vol 35 (3) ◽  
pp. 142-147
Author(s):  
Tomás Martínez-Trinidad ◽  
W. Todd Watson ◽  
Michael Arnold ◽  
Leonardo Lombardini ◽  
David Appel
Keyword(s):  
Chlorophyll Fluorescence ◽  
Root Growth ◽  
Isotope Composition ◽  
Net Photosynthesis ◽  
Growth Indices ◽  
Glucose Content ◽  
Quercus Virginiana ◽  
Carbohydrate Concentration ◽  
Live Oak ◽  
Potential Option

This study evaluates the effects of carbohydrate injections on the growth and vitality of live oak (Quercus virginiana P. Miller). Glucose, sucrose, or a 50:50 mixture of both carbohydrates at increasing concentrations [0, 40, 80, and 120 g/L (0, 5.3, 10.6, and 16.0 oz/gal)] were injected into live oaks. Trunk and root growth, net photosynthesis, root and twig carbohydrate concentration, and chlorophyll fluorescence were monitored. Isotope composition of twig and root samples was measured as an indicator of injected carbohydrate distribution. There were significant differences (P < 0.05) in trunk growth among types of carbohydrates, but no significant differences for carbohydrate concentrations. The mixtures of sucrose and glucose had the largest effect on growth compared to either sugar alone, suggesting that glucose and sucrose alone were used in processes other than trunk growth. 50:50 mixtures caused a greater effect on overall mean growth indices than either sugar alone. Glucose content in twigs and starch in roots were significantly different (P < 0.05) among overall means for concentrations with increased levels found in trees treated with the greatest concentrations. Chlorophyll fluorescence Fv/Fm revealed highly significant differences (P < 0.001) among overall concentrations. Carbon isotope values did not reveal a definite trend that corroborated the exogenous carbohydrate distribution. Results from this experiment suggest that carbohydrate trunk injections can have an impact on growth and vitality of live oak.

scholarly journals Automatic Estimation of Crop Disease Severity Levels Based on Vegetation Index Normalization

2020 ◽  
Vol 12 (12) ◽  
pp. 1930 ◽  
Author(s):  
Hengqian Zhao ◽  
Chenghai Yang ◽  
Wei Guo ◽  
Lifu Zhang ◽  
Dongyan Zhang
Keyword(s):  
Disease Severity ◽  
Precision Agriculture ◽  
Vegetation Index ◽  
Hyperspectral Imagery ◽  
Vegetation Indices ◽  
The United States ◽  
Ground Survey ◽  
Severity Grading ◽  
Crop Disease ◽  
Survey Results

The timely monitoring of crop disease development is very important for precision agriculture applications. Remote sensing-based vegetation indices (VIs) can be good indicators of crop disease severity, but current methods are mainly dependent on manual ground survey results. Based on VI normalization, an automated crop disease severity grading method without the use of ground surveys was proposed in this study. This technique was applied to two cotton fields infested with different levels of cotton root rot in south Texas in the United States, where airborne hyperspectral imagery was collected. Six typical VIs were calculated from the hyperspectral imagery and their histograms indicated that VI normalization could eliminate the influences of variable field conditions and the VI value range variations, allowing a potentially broader scope of application. According to the analysis of the obtained results from the spectral dimension, spatial dimension and descriptive statistics, the disease grading results were in general agreement with previous ground survey results, proving the validity of the disease severity grading method. Although satisfactory results could be achieved from different types of VI, there is still room for further improvement through the exploration of more VIs. With the advantages of independence of ground surveys and potential universal applicability, the newly proposed crop disease grading method will be of great significance for crop disease monitoring over large geographical areas.

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