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1. Altitudinal changes in photosynthetic pathways of floristic elements in southern Sinai, Egypt

Creator:
Sayed, O. H. and Mohamed, M. K.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
C3, C4, and ecophysiology
Language:
Multiple languages
Description:
High altitude profoundly influenced plant diversity and distribution on mountains of southern Sinai (Egypt). Plants exhibiting the C3-mode of photosynthesis were widely distributed along the altitudinal transect. Plants exhibiting the C4-mode were restricted below an altitude of about 1400 m above sea level. The transition from C3-dominated areas to C4-dominated areas occurred between 1200 and 1400 m a.s.l. and O. H. Sayed, M. K. Mohamed.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2. Analysis of photosynthetic responses and adaptation to nitrogen starvation in Chlorella using in vivo chlorophyll fluorescence

Creator:
Sayed, O. H.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
carotenoids, oxygen evolution, photosystem 2, species differences, and respiration
Language:
Multiple languages
Description:
Nitrogen (N) starvation resulted in degreening, inhibition of photosynthetic oxygen evolution and dark respiration, reduced survival, and increased age-specific mortality in both Chlorella fusca and Chlorella vulgaris. Analysis of in vivo chlorophyll (Chl) fluorescence induction kinetics revealed the presence of N-starvation-induced changes at the level of degreened thylakoids in both species. These changes included decreased yield of the photochemistry of photosystem 2 (PS2), and a declined photosynthetic efficiency. Synthesis of secondary carotenoids represented a biochemical change in carotenogenesis that had a photoprotective effect in degreened C. fusca. This inferred photoprotection was reflected in the delayed inhibition of oxygen evolution and improved survival of C. fusca under N-starvation. The effect was further elucidated by comparison with C. vulgaris which was not able to synthesize secondary carotenoids under the same conditions.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

3. Chlorophyll fluorescence as a tool in cereal crop research

Creator:
Sayed, O. H.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
barley, chilling, drought, heat, maize, oat, rice, sorghum, salinity, stress, and wheat
Language:
Multiple languages
Description:
Chlorophyll (Chl) fluorescence is a subtle reflection of primary reactions of photosynthesis. Intricate relationships between fluorescence kinetics and photosynthesis help our understanding of photosynthetic biophysical processes. Chl fluorescence technique is useful as a non-invasive tool in eco-physiological studies, and has extensively been used in assessing plant responses to environmental stress. The review gives a summary of some Chl fluorescence parameters currently used in studies of stress physiology of selected cereal crops, namely water stress, heat stress, salt stress, and chilling stress.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4. Crassulacean Acid Metabolism 1975-2000, a check list

Creator:
Sayed, O. H.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
angiosperms, CAM inducers, CAM modifications, CAM types, carbon discrimination, ferns, gymnosperms, habitat, and phosphoenolpyruvate carboxylase
Language:
Multiple languages
Description:
A list of plant species documented over the past 25 years to exhibit Crassulacean Acid Metabolism (CAM) is presented. The list compiles all available information on these species including their growth habits, succulent parts, carbon isotope discrimination values, CAM types, CAM inducers, and CAM modifications.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

5. Photosynthetic adaptation and survival strategy of Duvalia velutina in an extremely arid environment

Creator:
Masrahi, Y. S., Al-Turki, T. A., and Sayed, O. H.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, photosynthesis, chlorophyll fluorescence, CAM, CAM-idling, drought, Duvalia velutina, nurse association, photoprotection, 2, and 581
Language:
Multiple languages
Description:
Leafless Duvalia velutina Lavranos (Apocynaceae) is an arido-active stem succulent common in the arid region southwest of the Arabian Peninsula. This region is characterized by a short wet season with erratic rainfall and a long dry season with high temperature and high irradiance. We investigated the survival strategy of D. velutina by studying nurse association, gas exchange, and chlorophyll fluorescence. Results showed that D. velutina exhibited the strict nurse association with shade for protection against heat and high irradiance. Results also showed that D. velutina is an obligate CAM plant with ample physiotypic plasticity involving a shift to CAM-idling under prolonged drought. Chlorophyll fluorescence measurements revealed water stress-induced reduction of PSII activity occurring in concomitance with a marked rise of nonphotochemical quenching and chlorenchyma anthocyanin content. These results reflected photoprotective capacity involving nonradiative excess energy dissipation and antioxidative attributes. We concluded that the complex survival strategy of D. velutina in its natural arid habitat includes a multifaceted interplay of nurse association, physiotypic plasticity, and photoprotective mechanisms., Y. S. Masrahi, T. A. Al-Turki, O. H. Sayed., and Obsahuje seznam literatury
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public