We provide here a general introduction on chlorophyll (Chl) a fluorescence, then we present our measurements on fast (< 1 s) induction curves (the so-called OJIP transients) on dark-adapted intact leaves of Arabidopsis thaliana, under five different light intensities [in the range of ~ 500 to ~ 3,000 µmol(photons) m‒2 s‒1] using two different instruments: Handy PEA (Hansatech Instruments, UK; excitation light, 650 nm) and FluorPen (model FP-110; Photon Systems Instruments, The Czech Republic; excitation light, 470 nm). We then discuss the observed differences in the OJIP curves, as well as in Fo (F20μs, F50μs, or the extrapolated Ft→0), FP (the peak), and the ratios FP/Fo, and Fv (= FP ‒ Fo)/FP in terms of differences in excitation light intensity and absorptance (or absorbance) of the excitation light by the leaves, and other factors, as well as the data available in the literature. We suggest that such measurements be accompanied, in the future, by parallel measurements on Chl a fluorescence imaging, an area pioneered by Hartmut K. Lichtenthaler., B. Padhi, G. Chauhan, D. Kandoi, A. Stirbet, B. C. Tripathy, G. Govindjee., and Obsahuje bibliografické odkazy
How the photosynthetic characteristics of insect-resistant transgenic cotton (Gossypium hirsutum L.) respond to light or whether this genetic transformation could result in unintended effects on their photosynthetic and physiological processes is not well known. Two experiments were conducted to investigate the shapes of net photosynthetic rate (P N), stomatal conductance (g s), apparent light use efficiency (LUEapp) and water use efficiency (WUE) light-response curves for single leaves of Bt (Bacillus thuringiensis) and Bt+CpTI (cowpea trypsin inhibitor) transgenic cotton plants and their non-transgenic counterparts, respectively. Results showed that the significant difference in response of P N and WUE to light between transgenic cotton and non-transgenic cotton occured but not always throughout the growing season or in different experiments or for all transgenic cotton lines. It was highly dependent on growth stage, culture condition and variety, but no obvious difference between any transgenic cotton and non-transgenic cotton in the shapes of g s and LUEapp light-response curves was observed in two experiments at different growth stages. In the field experiments, transgenic Bt+CpTI cotton was less sensitive to response of P N to high irradiance at the boll-opening stage. In pot experiments, WUE light-response curves of both Bt transgenic cotton and Bt+CpTI transgenic cotton progressively decreased whereas non-transgenic cotton slowly reached a maximum at high irradiance at boll-opening stage. We supposed that culture environment could affect the photosynthesis of transgenic cotton both directly and indirectly through influencing either foreign genes expression or growth and physiological processes. and C. X. Sun ... [et al.].
Empirical Mode Decomposition (EMD) is suitable to process the nonlinear and non-stationary time series for filtering noise out to extract the signals. The formal errors are provided along with Global Navigation Satellite System (GNSS) position time series, however, not being considered by the traditional EMD. In this contribution, we proposed a modified approach that called weighted Empirical Mode Decomposition (weighted EMD) to extract signals from GNSS position time series, by constructing the weight factors based on the formal errors. The position time series over the period from 2011 to 2018 of six permanent stations (SCBZ, SCJU, SCMN, HLFY, FJPT, SNXY) were analyzed by weighted EMD, as well as the traditional EMD. The results show that weighted EMD can extract more signals than traditional EMD from original GNSS position time series. Additionally, the fitting errors were reduced 14.52 %, 12.25 % and 8.06 % for North, East and Up components for weighted EMD relative to traditional EMD, respectively. Moreover, 100 simulations of four stations are further carried out to validate the performances of weighted EMD and traditional EMD. The mean Root Mean Squared Errors (RMSEs) are reduced from traditional EMD to weighted EMD with the reductions of 9.08 %, 9.63 % and 6.84 % for East, North and Up components, respectively, which highlights the necessity of considering the formal errors. Therefore, it reasonable to conclude that weighted EMD can extract the signals more than traditional EMD, which can be suggested to analyze GNSS position time series with formal errors., Xiaomeng Qiu, Fengwei Wang, Yunqi Zhou and Shijian Zhou., and Obsahuje bibliografii