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Plant physiology A big issue for trees (2005)

Peñuelas, Josep

[s.l.] : Nature Publishing Group

Nature 437 (2005), S. 965-966

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ISSN: 1476-4687

Source: Nature Archives 1869 - 2009

Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics

Notes: [Auszug] What controls senescence and lifespan? As they describe in Ecology Letters, Mencuccini et al. have tackled this question for trees, which may live for many centuries and grow to more than 100 metres in height. With increasing age and size, growth tends to slow and a tree is more likely to die. One ...

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1038/437965a

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Relationship between photosynthetic radiation-use efficiency of barley canopies and the photochemical reflectance index (PRI) (1996)

Filella, Iolanda ; Amaro, Teo ; Araus, Jose Luis ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Physiologia plantarum 96 (1996), S. 0

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ISSN: 1399-3054

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Some processes of excess radiation dissipation have been associated with changes in leaf reflectance near 531 nm. We aimed to study the relations between the photochemical reflectance index (PRI) derived from this signal, and photosynthetic radiation-use efficiency (defined as net CO2 assimilation rate/incident photon flux density) in a cereal canopy. Measurements of reflectance, fluorescence, gas exchange and xanthophyll cycle pigments were made in the morning, midday and afternoon in barley canopies with two levels of nitrogen fertilization. The photosynthetic radiation-use efficiency decreased at midday, mainly in the third leaf, in both treatments, with lower values for the nitrogen deficient leaves. The zeaxanthin content showed the inverse pattern, increasing at midday and in the nitrogen deficient treatment. The photosynthetic radiation-use efficiency was well correlated with the epoxidation state, EPS (violaxanthin + 0.5 antheraxanthin)/(violaxanthin + antheraxanthin + zeaxanthin). The PRI [here defined as (R539 - R570)/(R539+ R570)] was significantly correlated with epoxidation state and zeaxanthin and with photosynthetic radiation-use efficiency. These results validate the utility of PRI in the assessment of radiation-use efficiency at canopy level.