ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
The objectives of this study were to determine the effects of UV-B radiation and atmospheric carbon dioxide concentrations ([CO2]) on leaf senescence of cotton by measuring leaf photosynthesis and chlorophyll content and to identify changes in leaf hyperspectral reflectance occurring due to senescence and UV-B radiation. Plants were grown in controlled-environment growth chambers at two [CO2] (360 and 720 µmol mol−1) and three levels of UV-B radiation (0, 7.7 and 15.1 kJ m−2 day−1). Photosynthesis, chlorophyll, carotenoids and phenolic compounds along with leaf hyperspectral reflectance were measured on three leaves aged 12, 21 and 30 days in each of the treatments. No interaction was detected between [CO2] and UV-B for any of the measured parameters. Significant interactions were observed between UV-B and leaf age for photosynthesis and stomatal conductance. Elevated [CO2] enhanced leaf photosynthesis by 32%. On exposure to 0, 7.7 and 15.1 kJ of UV-B, the photosynthetic rates of 30-day-old leaves compared with 12-day-old leaves were reduced by 52, 76 and 86%, respectively. Chlorophyll pigments were not affected by leaf age at UV-B radiation of 0 and 7.7 kJ, but UV-B of 15.1 kJ reduced the chlorophylls by 20, 60 and 80% in 12, 21 and 30-day-old leaves, respectively. The hyperspectral reflectance between 726 and 1142 nm showed interaction for UV-B radiation and leaf age. In cotton, leaf photosynthesis can be used as an indicator of leaf senescence, as it is more sensitive than photosynthetic pigments on exposure to UV-B radiation. This study revealed that, cotton leaves senesced early on exposure to UV-B radiation as indicated by leaf photosynthesis, and leaf hyperspectral reflectance can be used to detect changes caused by UV-B and leaf ageing.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.0031-9317.2004.00314.x
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