Field experiments were conducted in Sicily (south Italy) to assess chlorophyll (Chl) fluorescence parameters in response of potato crop to nitrogen dose, to variation in genotype and in plant age, and to detect relationships between Chl content, fluorescence parameter Fv/Fm, and tuber yield. The experiment included five nitrogen doses (0, 10, 20, 30, and 40 g m-2) and four genotypes (Spunta, Sieglinde, Daytona, and Igea). Chl fluorescence parameters (initial fluorescence, F0, maximum fluorescence, Fm, variable fluorescence, Fv, Fv/Fm, Tmax (the time required to reach Fm), and Chl content were measured weekly between the appearance of the fifth and sixth leaves and the onset of plant senescence. A positive linear relationship was established between nitrogen supply and Chl content, F0, and Tmax. Nitrogen supply up to 10 g m-2 also had a positive effect on Fm and Fv, but above this rate it reduced Fv/Fm. Spunta had the highest Chl content, Fm, Fv, and Fv/Fm, but the lowest F0, whereas Sieglinde had the lowest Chl content, Fv, Fv/Fm, and Tmax and the highest F0. The cvs. Igea and Daytona exhibited intermediate Chl fluorescence parameters. Chl content and Tmax decreased with increasing plant age, whereas F0, Fm, and Fv increased until complete canopy development and thereafter declined until crop maturity. Tuber and plant dry matter yield were significantly correlated with Chl content, F0, and Tmax. Thus Chl fluorescence and content detect differences in the response of potato to N supply, can discriminate between genotypes, predict plant age, and yield performance under field conditions. and G. Mauromicale, A. Ierna, M. Marchese.
We tested whether cheap and quick chlorophyll (Chl) fluorescence can be used in ecophysiological field studies as proxies for
gas-exchange measurements. We measured net photosynthetic rate at saturating irradiance and ambient atmospheric CO2 concentrations (PNsat), maximum carboxylation rate (Vcmax), maximum quantum yield of PSII (Fv/Fm), the performance index (PIabs), leaf nitrogen (Narea), and carbon isotope discrimination (Δ13C) within four herbaceous species along two elevational gradients. We analysed the relationship between Chl fluorescence and gas-exchange parameters and their link to indirect assessment of plant performance via ecophysiological traits. Fv/Fm showed no relationship to PNsat and only weak relationships to Vcmax. PIabs was positively related to PNsat and Vcmax. PIabs, PNsat, and Vcmax were positively associated with Narea and negatively to Δ13C, whereas Fv/Fm showed no relationship to Narea and a positive to Δ13C. Thus, PIabs might be suitable to characterize the photosynthetic activity when aiming on large numbers of samples., S. F. Bucher, M. Bernhardt-Römermann, C. Römermann., and Obsahuje bibliografii
Sun-and shade-adapted plants of Ailanthus altissima utilized thermal-dissipative photoprotection (NPQ) across a range of photosynthetic photon flux densities (PPFD), with higher NPQ and lower maximum quantum yield of photosystem 2 photochemistry (Fv/Fm) in sun-adapted individuals, suggesting increased engagement of antennae-based quenching. Photosynthetic quantum requirements (Qreq; number of photons per CO2) were similar in sun and shade plants, but were low and comparable to forest understory species. Diurnal measurements showed that PPFDs in both habitats were consistently above photosynthetic compensation irradiance, and frequently exceeded saturating values. In addition, sun- and shade-adapted individuals possessed stomata that tracked short-term fluctuations in PPFD. Thus A. altissima may be unique in that it couples high, shade-plant like photosynthetic efficiency with high photosynthetic capacity in high-irradiance, while stomatal attributes that optimize water use efficiency are maintained in the shade. These features may contribute to success of A. altissima in establishing in disturbance-prone urban systems, and facilitate its spread into more PPFD-limited and competitive natural ecosystems.
The effect of water deficit on chlorophyll fluorescence, sugar content, and growth parameters of strawberry (Fragaria×ananassa Duch. cv. Elsanta) was studied. Drought stress caused significant reductions in leaf water potential, fresh and dry masses, leaf area, and leaf number. A gradual reduction of photochemical quenching (qP) and quantum efficiency (ΦPS2) was observed under drought stress while non-photochemical quenching (qN) increased. Maximum efficiency of photosystem 2 (Fv/Fm) was not affected by drought stress. and F. Razavi ... [et al.].
This study examined the utility of the ratio of variable fluorescence to maximum fluorescence (Fv/Fm) to detect freezing injury on buds of two Vitis vinifera cultivars: Pinot noir and Pinot gris. Freezing treatments on buds caused a decrease both in Fv/Fm and percentage of budburst, more severely on Pinot gris than Pinot noir, specifically at the lower temperature (-20°C). Fv/Fm ratio showed a close correlation with percentage of budburst, and a threshold of the lethal Fv/Fm was proposed as an indicator of bud mortality. and L. Zulini, C. Fischer, M. Bertamini.
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.
Acid rain causes damages to forest ecosystems. Here, we reported that acid rain could promote plant growth. From 2006 to 2009, one-year-old Elaeocarpus glabripetalus seedlings were sprayed with simulated acid rain (AR) (pH 2.5, 4.0, and 5.6). The maximum quantum yield efficiency of PSII and the actual photochemical quantum efficiency of PSII increased with rising AR acidity, which facilitated chlorophyll fluorescence and plant growth, as shown by a declining minimal fluorescence yield of dark-adapted state with little damage to the PSII reaction center. After the second experimental year, the plant height and ground diameter were greater at pH 2.5 than those found at pH 4.0 and 5.6. This showed the positive effects of AR on the seedling growth and photosynthesis of E. glabripetalus, revealing that this species exhibited a stronger resistance to acid deposition than some other tree species. This implies that E. glabripetalus is an acid-tolerant species., M.H. Liu, L.T. Yi, S.Q. Yu, F. Yu, X.M. Yin., and Obsahuje bibliografii
Photosynthetic fluorescence emission spectra measurement at the temperature of 77 K (-196°C) is an often-used technique in photosynthesis research. At low temperature, biochemical and physiological processes that modulate fluorescence are mostly abolished, and the fluorescence emission of both PSI and PSII become easily distinguishable. Here we briefly review the history of low-temperature chlorophyll fluorescence methods and the characteristics of the acquired emission spectra in oxygen-producing organisms. We discuss the contribution of different photosynthetic complexes and physiological processes to fluorescence emission at 77 K in cyanobacteria, green algae, heterokont algae, and plants. Furthermore, we describe practical aspects for obtaining and presenting 77 K fluorescence spectra., J. J. Lamb, G. Røkke, M. F. Hohmann-Marriott., and Obsahuje bibliografické odkazy
Graft union development in plants has been studied mainly by destructive methods such as histological studies. The aim of this work was to evaluate whether the chlorophyll fluorescence imaging (CFI) technique is sensitive enough to reflect changes at the cellular level in different Solanaceae grafted plants 30 d after grafting, when both grafted partners were well fused and strong enough in all plant combinations. The pepper cultivar ‘Adige’ was grafted onto different Capsicum spp. accessions typified with different compatibility degrees; eggplant was grafted on Solanum torvum and pepper homografts as compatible unions; pepper was grafted on S. torvum and on tomato as incompatible unions. ‘Adige’/’Adige’ and ‘Adige’/pepper A25 showed a higher maximum quantum efficiency of PSII associated with higher values of actual quantum efficiency of PSII and photochemical quenching as well as with vascular regeneration across the graft interface. Our results highlighted that CFI changes reflected histological observations in grafted Solanaceae plants., C. Penella, A. Pina, A. San Bautista, S. López-Galarza, Á. Calatayud., and Obsahuje seznam literatury
Chlorophyll a fluorescence analysis (CFA) has been accepted to study postharvest activity and stability of photosynthesis of vegetables and salad greens, and some fruits. Commercial chlorophyll fluorescence imaging (CFI) systems may provide additional insight into spatial and temporal dynamics of photosynthesis. This yields valuable information on the effects of postharvest handling and processing (sorting, cutting, packaging, etc.) on physiological activity and 'internal quality' of green produce, and its changes. Here, meaning and physiological basics of relevant fluorescence parameters is briefly summarised, while major focus is on recent applications of CFI to evaluate quality and quality maintenance during postharvest handling and minimal processing of fresh fruits and vegetables. CFI is given surprisingly little attention in the monitoring of postharvest quality, although it is suitable for adjusting and/or optimising innovative postharvest techniques. Knowledge of the physiological base and the limit of interpretation is indispensable for meaningful interpretations of results to draw correct consequences., W. B. Herppich., and Obsahuje bibliografické odkazy