scholarly journals Some Photosynthetic Characteristics of Citrus Leaves

1968 ◽  
Vol 21 (5) ◽  
pp. 895 ◽  
Author(s):  
PE Kriedemann
Keyword(s):  
Photosynthetic Activity ◽  
Photosynthetic Characteristics ◽  
Optimum Conditions ◽  
Mature Leaves ◽  
Infrared Gas Analyser ◽  
Citrus Leaves ◽  
Photosynthesis And Respiration

Photosynthesis and respiration were measured in the laboratory with an infrared gas analyser using attached leaves of well-established orange and lemon trees growing in pots. Under optimum conditions the photosynthetic activity of mature leaves reached 10-12 mg C02/hr/dm2.

scholarly journals Automated Detection of Tetranychus urticae Koch in Citrus Leaves Based on Colour and VIS/NIR Hyperspectral Imaging

Agronomy ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1002
Author(s):  
María Gyomar Gonzalez-Gonzalez ◽  
Jose Blasco ◽  
Sergio Cubero ◽  
Patricia Chueca
Keyword(s):  
Hyperspectral Imaging ◽  
Tetranychus Urticae ◽  
Visual Inspection ◽  
Vision System ◽  
Automated Detection ◽  
Nutritional Deficiencies ◽  
Phyllocnistis Citrella ◽  
Mature Leaves ◽  
Citrus Leaves ◽  
Tetranychus Urticae Koch

Tetranychus urticae Koch is an important citrus pest that produces chlorotic spots on the leaves and scars on the fruit of affected trees. It is detected by visual inspection of the leaves. This work studies the potential of colour and hyperspectral imaging (400–1000 nm) under laboratory conditions as a fast and automatic method to detect the damage caused by this pest. The ability of a traditional vision system to differentiate this pest from others, such as Phyllocnistis citrella, and other leaf problems such as those caused by nutritional deficiencies, has been studied and compared with a more advanced hyperspectral system. To analyse the colour images, discriminant analysis has been used to classify the pixels as belonging to either a damaged or healthy leaves. In contrast, the hyperspectral images have been analysed using PLS DA. The rate of detection of the damage caused by T. urticae with colour images reached 92.5%, while leaves that did not present any damage were all correctly identified. Other problems such as damage by P. citrella were also correctly discriminated from T. urticae. Moreover, hyperspectral imaging allowed damage caused by T. urticae to be discriminated from healthy leaves and to distinguish between recent and mature leaves, which indicates whether it is a recent or an older infestation. Furthermore, good results were achieved in the discrimination between damage caused by T. urticae, P. citrella, and nutritional deficiencies.

scholarly journals Effect of Petroleum Oil Spray on Photosynthesis and Respiration in Citrus Leaves

1952 ◽  
Vol 27 (2) ◽  
pp. 269-278 ◽  
Author(s):  
R. T. Wedding ◽  
L. A. Riehl ◽  
W. A. Rhoads
Keyword(s):  
Citrus Leaves ◽  
Photosynthesis And Respiration ◽  
Petroleum Oil

scholarly journals A role for GLABRA1 in dark-induced senescence

2019 ◽  
Author(s):  
Aleksandra Eckstein ◽  
Joanna Grzyb ◽  
Paweł Hermanowicz ◽  
Justyna Łabuz ◽  
Agnieszka Katarzyna Banaś
Keyword(s):  
Arabidopsis Thaliana ◽  
Photosynthetic Activity ◽  
Practical Importance ◽  
Wild Type ◽  
Mature Leaves ◽  
Trichome Formation ◽  
Myb Gene ◽  
Black Paper ◽  
In The Wild ◽  
Senescence Associated Genes

The GLABRA (GL1) gene, belonging to the transcription factor-encoding myb gene family, is responsible for trichome formation in Arabidopsis thaliana (L.) Heynh. The leaves and stems of glabra1 mutant plants are devoid of trichomes. Having an easily observable phenotype, the gl1 mutation was one of the first markers established for genetic mapping of Arabidopsis thaliana. Since then, the GL1 gene has been assigned roles in other processes, also related to leaf structure. In this study we present some previously undescribed effects of the gl1 mutation on dark-induced senescence. This process was induced by covering selected mature leaves of Columbia wild-type and gl1 Arabidopsis with black paper for 4 days, while the plants remained growing in a normal photoperiod. While no visible differences in the external symptoms of senescence could be observed in the darkened leaves, the expression of senescence-associated genes was significantly lower in gl1 plants as compared to the wild type. The darkening of leaves led to a decrease in photosynthetic activity and the expression of photosynthesis-associated genes, in comparison to the control leaves. This effect was much less pronounced in gl1 than in the wild type plants. Therefore, gl1 plants seem to be less susceptible to dark-induced aging, suggesting a possible role for the GL1 gene in controlling the onset and progress of senescence. This result is also of practical importance, since gl1 is the genetic background of many other mutants. It may therefore be advisable to revise some of the results obtained with such mutants in light of findings presented here.

Evaluation for Photosynthetic Characteristics in upland cotton germplasm based on chlorophyll a fluorescence

2020 ◽  
Author(s):  
ying sun ◽  
Xiaoming Xu ◽  
Wenqing Dong ◽  
Xiongming Du ◽  
Yinhua Jia ◽  
...  
Keyword(s):  
Gossypium Hirsutum ◽  
Chlorophyll A ◽  
Chlorophyll A Fluorescence ◽  
Upland Cotton ◽  
Genetic Improvement ◽  
Photosynthetic Activity ◽  
Photosynthetic Characteristics ◽  
Germplasm Resources ◽  
Fluorescence Parameters

Abstract Background: The research of photosynthetic characteristics of germplasm resources of cotton ( Gossypium hirsutum L.) provides reference for genetic improvement on cotton cultivars. Chlorophyll a fluorescence (CF) is widely used for analysis of photosynthetic activity of plants leaves. However, large number of Chlorophyll a fluorescence parameters (CFPs) and inconsistency CFPs application in different studies confuse researchers, which greatly limit the accuracy of photosynthesis analysis. In this study, all 53 CFPs of 189 upland cotton cultivars (strains) measured by handy PEA were screened at 12:00 and 17:00 separately. Results: 9 CFPs including PI(abs), DIo/CSo, PI(abs, total), Sm/T, Vj, Eto/CSo, REo/CSo, RC/CSo and N at 12:00 and 8 CFPs including PI(abs, total), PI(abs), DIo/CSo, Sm/T, REo/CSo, N, Vj and Eto/CSo at 17:00 are suitable for screening of upland cotton cultivars (strains). The screened CFPs classify and evaluate the photosynthetic characteristics of upland cotton cultivars (strains). Conclusions: CFPs selected can be effect and consistent parameters to evaluate photosynthetic activity of cotton germplasm.

scholarly journals Modelling of photosynthesis, respiration, and nutrient yield coefficients in Scenedemus almeriensis culture as a function of nitrogen and phosphorus

2021 ◽  
Author(s):  
A. Sánchez Zurano ◽  
C. Gómez Serrano ◽  
F. G. Acién-Fernández ◽  
J. M. Fernández-Sevilla ◽  
E. Molina-Grima
Keyword(s):  
Photosynthetic Activity ◽  
Culture Media ◽  
Phosphorus Concentration ◽  
High Concentration ◽  
Nitrogen And Phosphorus ◽  
Monod Equation ◽  
Nutrient Yield ◽  
Nutrients Availability ◽  
High Concentrations ◽  
Photosynthesis And Respiration

AbstractPhoto-respirometric tecniques are applied for evaluating photosynthetic activity in phototrophic organisms. These methods allow to evaluate photosynthetic response under different conditions. In this work, the influence of nutrient availability (nitrate, ammonium, and phosphate) on the photosynthesis and respiration of Scenedesmus almeriensis was studied using short photo-respirometric measurements. Both photosynthesis and respiration increasing until saturation value and consecutively diminishing, presenting inhibition by high concentrations. Regarding the influence of phosphorus concentration in microalgae cells, a similar hyperbolic trend was observed but no inhibition was observed at high concentration. Based on these experimental data, the respiration, and the photosynthesis rate of S. almeriensis were modelled using Haldane equation for nitrate and ammonium data, and Monod equation for phosphate data. In addition, experiments were performed to determine the yield coefficients for both nitrogen and phosphorus in S. almeriensis cultures. The data showed that the nitrogen and phosphorous coefficient yields are not constant, being modified as a function of nutrients concentration, presenting the luxury uptake phenomena. Finally, the proposed models were incorporated into a simulation tool to evaluate the photosynthetic activity and the nutrient yield coefficients of S. almeriensis when different culture media and wastewaters are used as a nitrogen and phosphorous source for its growth.Key points• Microalgal photosynthesis/respiration vary as a function of nutrients availability.• Photosynthesis inhibition appears at high N-NO3-and N-NH4+concentrations.• Nutrient yield coefficients are influenced by luxury uptake phenomenon. Graphical abstract

scholarly journals Experimental researches on vegetable assimilation and respiration.—XV. The development of photosynthetic activity during germination of different types of seeds

1922 ◽  
Vol 94 (656) ◽  
pp. 12-19 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Photosynthetic Activity ◽  
Dry Weight ◽  
Natural Conditions ◽  
Full Activity ◽  
Mature Leaves ◽  
Different Types ◽  
Experimental Researches ◽  
Further Development ◽  
Growth Experiments

In a previous paper (2) the writer has shown that the photosynthetie activity of the seedling leaves of Phaseolus vulgaris , Vida Faba and Arena sativa is zero or very small for some time after their first appearance, and that oven when further development of chlorophyll is inhibited the activity increases from day to day. Although the photosynthetic activity was measured under such conditions that carbon dioxide was not limiting the rate of assimilation, yet an investigation of the results of growth experiments (3) indicates that under natural conditions of carbon dioxide supply the assimilation of the seedling leaves of maize is very much smaller than that of mature leaves. Tables I, which contains results of experiments carried out by the writer on maize, and la, a collection of scattered results from Willstatter’s work (8), show that some considerable lapse of time is necessary before the seedling leaves of maize attain their full activity, whether light or temperature be limiting; in Willstatter’s experiments temperature was limiting. Experiments recorded by Brenchley (1) show that in the case of Pisum sativum it is some time before the seedling attains a dry weight equal to that of the seed. In the case of Helianthus , however, the evidence from growth experiments (4) indicates that in this plant the seedling leaves, here the cotyledons, assimilate quite actively as soon as they appear above ground, or that at most hardly a day elapses before they reach their full activity. This evidence from growth experiments suggested an investigation of the case of Helianthus on the same lines as that of Phaseolus described in the previous paper. The results of the experiments are recorded in Table II. The same method and apparatus was used as in the previous case (2).

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