We investigated the effects of supplementary KNO3 and NaCl on one-year-old, potted Valencia orange (Citrus sinensis) scions grafted on Iranian mandarin Bakraii [Citrus reticulate × Citrus limetta] (Valencia/Bakraii) and Carrizo citrange [C. sinensis × Poncirus trifoliata] (Valencia/Carrizo) rootstocks. After watering plants for 60 days with 50 mM NaCl, the lowest reduction in dry mass, stomatal conductance, and chlorophyll (Chl) content was found in Valencia/Bakraii. Bakraii accumulated more Cl- and Na+ in roots and transferred less to Valencia leaves compared with Carrizo rootstock. Moreover, higher net photosynthetic rate was found in Valencia/Bakraii than those on Carrizo rootstock. NaCl caused a decrease in the maximal efficiency of PSII photochemistry (Fv/Fm) and effective quantum yield (ΦPSII) but elevated coefficient of nonphotochemical quenching. Salinity reduced Ca2+, Mg2+, and total N contents, and increased Na+/K+ ratio in leaves and roots of both grafting combinations. Salinity increased K+ and proline content in leaves and decreased K+ concentrations in roots of both grafting combinations. In salinized plants, nitrate supplementation (10 mM KNO3) reduced leaf abscission, Cl-, Na+, Na+/K+, and Ca2+ concentrations in leaves and roots of both combinations. K+ and N concentrations and proline increased in leaves of the nitrate-supplemented salinized plants. Supplementary nitrate increased leaf number and area, stem elongation, Chl content, Fv/Fm, and ΦPSII and stimulated photosynthetic activity. Thus, nitrate ameliorated the deleterious effects of NaCl stress and stimulated the plant metabolism and growth. It can be used as a vital treatment under such condition., D. Khoshbakht, A. Ghorbani, B. Baninasab, L. A. Naseri, M. Mirzaei., and Obsahuje bibliografii
a1_The effect of a wide range of temperatures (-15 and 60°C) in darkness or under strong irradiation [1,600 μmol(photon) m-2 s-1] on quantum yield of photosystem II photochemistry and xanthophyll cycle pigments was investigated in a tropical fruit crop (Musa sp.) and a temperate spring flowering plant (Allium ursinum L.). In darkness within the nonlethal thermal window of A. ursinum (from -6.7 to 47.7°C; 54.5 K) and of Musa sp. (from -2.2°C to 49.5°C; 51.7 K) maximal quantum yield of PSII photochemistry (Fv/Fm) was fairly unaffected by temperature over more than 40 K. At low temperature Fv/Fm started to drop with ice nucleation but significantly only with initial frost injuries (temperature at 10% frost damage; LT10). The critical high temperature threshold for PSII (Tc) was 43.8°C in A. ursinum and 44.7°C in Musa sp. Under strong irradiation, exposure to temperatures exceeding the growth ones but being still nonlethal caused photoinhibition in both species. Severity of photoinhibition increased with increasing distance to the growth temperature range. ΔF/Fm′ revealed distinctly different optimum temperature ranges: 27-36°C for Musa sp. and 18-27°C for A. ursinum exceeding maximum growth temperature by 2-7 K. In both species only at temperatures > 30°C zeaxanthin increased and violaxanthin decreased significantly. At nonlethal low temperature relative amounts of xanthophylls remained unchanged. At temperatures > 40°C β-carotene increased significantly in both species. In Musa sp. lutein and neoxanthin were significantly increased at 45°C, in A. ursinum lutein remained unchanged, neoxanthin levels decreased in the supraoptimal temperature range. In darkness, Fv/Fm was highly temperature-insensitive in both species., a2_Under strong irradiation, whenever growth temperature was exceeded, photoinhibition occurred with xanthophylls being changed only under supraoptimal temperature conditions as an antiradical defence mechanism., A. Dongsansuk, C. Lütz, and G. Neuner., and Obsahuje bibliografii
We studied growth and photosynthesis of cucumber (Cucumis sativus) seedlings under two vapor-pressure deficit levels (VPD; 0.4 and 3.0 kPa), two salinity levels (0 mM and 34 mM NaCl), and two CO2 concentrations ([CO2]; 400 and 1,000 μmol mol-1). Relative growth rate (RGR) decreased with increasing VPD, but the causal factor differed between salinity levels and CO2 concentrations. Under ambient [CO2], RGR decreased with increasing VPD at low salinity mainly due to decreased leaf area ratio (LAR), and decreased net assimilation rate (NAR) at high salinity. The decrease in intercellular [CO2] (Ci) with decreasing stomatal conductance caused by high VPD did not significantly limit net photosynthetic rate (PN) at low salinity, but PN was potentially limited by Ci at high salinity. At high [CO2], high VPD reduced LAR, but did not affect NAR. This is because the decrease in Ci occurred where slope of PN-Ci curve was almost flat., T. Shibuya, K. Kano, R. Endo, Y. Kitaya., and Obsahuje bibliografii
The maize weevil, Sitophilus zeamais (Motschulsky), is a major pest of stored grain kernels. Irradiation is an established technique for controlling insects in stored grain and is a major stress factor affecting these insects. Since heat shock protein (hsp) genes respond to this stress, we proposed that hsps may be associated with irradiated stress tolerance in S. zeamais. The responses of the maize weevil to exposure to ultraviolet-C (UV-C) and microwave irradiation were assessed at four developmental stages: egg, larva, pupa and adult. The results revealed that exposure to UV-C (254 nm, < 8 h) did not affect the survival of the maize weevils; however, Szhsp70, Szhsc70 and Szhsp90 mRNA levels significantly increased during the first 1 h of UV-C exposure. The median lethal time (LT50) of exposure to microwave irradiation indicated that the adult stage was more tolerant of microwave irradiation than the other developmental stages. Microwave irradiation enhanced the expression of the three hsps, but the intensity of up-regulation differed among the three genes, with Szhsp70 the most highly up-regulated. Our experiments revealed that UV-C and microwave irradiation influenced the expression profile of hsp genes in S. zeamais. At the tissue level, the gene responses to UV-C and microwave irradiation varied greatly in different tissues., Jatuporn Tungjitwitayakul, Nujira Tatun, Boongeua Vajarasathira, Sho Sakurai., and Obsahuje bibliografii
Bothriochloa ischaemum L. is an important species in many temperate regions, but information about the interactive effects of water stress and fertilization on its photosynthetic characteristics was inadequate. A pot experiment was conducted to investigate the effects of three water [80% (HW), 40% (MW), and 20% (LW) of field capacity (FC)] and four fertilization regimes [nitrogen (N), phosphorus (P), nitrogen with phosphorus (NP), and no fertilization] on leaf photosynthesis. Leaf gas exchange and photosynthetic light-response curves were measured at the flowering phase of B. ischaemum. Water stress decreased not only the leaf gas-exchange parameters, such as net photosynthetic rate (PN), stomatal conductance (gs), transpiration rate (E), and water-use efficiency (WUE) of B. ischaemum, but also downregulated
PN-photosynthetically active radiation (PAR) curve parameters, such as light-saturated net photosynthetic rate (PNmax), apparent quantum efficiency (AQE), and light compensation point (LCP). Fertilization (N, P, and NP) enhanced the daily mean PN values and PNmax under the HW regime. Addition of N (either alone or with P) improved the photosynthetic capacity of B. ischaemum under the MW and LW regimes by increasing PN, PNmax, and AQE and reducing dark respiration rate and LCP, but the addition of P alone did not significantly improve the photosynthetic performance. Decline in PN under each fertilization regime occurred during the day and it was caused mainly by nonstomatal limitation. Our results indicated that water was the primary limiting factor for photosynthesis in B. ischaemum, and that appropriate levels of N fertilization improved its potential photosynthetic capacity under water-deficit conditions. and W. Z. Xu, X. P. Deng, B. C. Xu.
a1_Soil water deficit is a major limitation to agricultural productivity in arid regions. Leaf photosynthesis can quickly recover after rewatering and remains at a higher level for a longer period, thus increasing crop yield and water-use efficiency (WUE). We tested our hypothesis that leaf photosynthesis and root activity of water-stressed cotton (Gossypium hirsutum L.) plants could quickly recover after rewatering at a certain growth stage and it should not influence a cotton yield but increase WUE. Treatments in this study included two degrees of water stress: mild water stress (V1) and moderate water stress (V2) imposed at one of four cotton growth stages [i.e., S1 (from the full budding to early flowering stage), S2 (from early flowering to full flowering), S3 (from full flowering to full bolling), and S4 (from full bolling to boll-opening)]. The soil water content before and after the water stress was the same as that in the control treatment (CK, 70-75% of field capacity). Water deficit significantly reduced the leaf water potential, net photosynthetic rate, and stomatal conductance in cotton. The extent of the decline was greater in S2V2 treatment compared to others. Water deficit also reduced root activity, but the extent of inhibition varied in dependence on soil depth and duration. When plants were subjected to S1V1, the root activity in the 20-100 cm depth recovered rapidly and even exceeded CK one day after rewatering. An overcompensation response was observed for both photosynthesis and aboveground dry mass within one to three days after rewatering. Compared with the CK, S1V1 showed no significant effect on the yield but it increased total WUE and irrigation WUE., a2_These results suggest that even a short-term water stress during the S1, S2 and S4 stages mitigated, with respect to the root activity, the negative effect of drought and enhanced leaf photosynthesis compensatory effects of rewatering in order to increase cotton WUE with drip irrigation under mulch in arid areas., H. H. Luo, Y. L. Zhang, W. F. Zhang., and Obsahuje seznam literatury
Transgenic lines of silver birch (Betula pendula) carrying the sugar beet chitinase IV gene were used to study the effects of the heterologous expression of a transgenic chitinase on the performance of lepidopteran herbivores. The effect of wounding the leaves of birch on the performance of lepidopteran larvae and the growth of trees was also studied. Larvae of Orgyia antiqua L., Lymantriidae, and Phalera bucephala L., Notodontidae, were separately fed on the leaves of transgenic and wild-type birch, and their performance measured using nutritional indices. The relative growth rate (RGR) of O. antiqua larvae fed transgenic leaves was significantly lower than that of larvae fed wild-type leaves. Furthermore, there is little evidence that transgenic chitinase affects survival but it was lowest for the group of larvae fed leaves with the highest expression of chitinase IV. Wounding did not have a significant effect on the performance of the larvae or on the growth of the branches of the trees. The growth of branches of particular transgenic lines, however, was significantly associated with tree line. The performance of P. bucephala larvae fed leaves of transgenic and wild-type birches did not differ. The leaves used in both experiments from transgenic trees were shorter than those from wild-type trees. Using transgenic birch expressing sugar beet chitinase IV to improve the resistance of birch to fungal diseases can have negative effects on O. antiqua larvae feeding on the leaves of these birches. P. bucephala, however, was not similarly affected, which indicates that these two ecologically similar lepidopteran species may differ in their response to transgenic chitinase., Liisa Vihervuori ... [et al.]., and Obsahuje seznam literatury
Traps baited with plant volatiles and/or bark beetle pheromones have been used to survey for exotic and potentially invasive bark and wood-boring beetles in North America since the mid-1990s. Recent discoveries of sex and aggregation pheromones in the Cerambycidae offer means of improving detection rates of longhorn beetles, but little is known of their effects on detection of bark and ambrosia beetles in the subfamily Scolytinae. Our objectives were to determine the efficacy of host volatile trap lures for survey and detection of Scolytinae species and whether that efficacy was affected by the addition of longhorn beetle pheromones. More than 12,000 specimens and 36 species of Scolytinae were collected in two field trapping bioassays conducted in the Russian Far East in 2009 and 2010. The lure combination of spruce blend (a blend of racemic α-pinene, (-) β-pinene, (+)-3-carene, (+)-limonene, and α-terpinolene) and ethanol significantly increased detection rates and mean catches of Hylastes brunneus Erichson, Hylastes obscurus Chapuis, Ips typographus (L.), and Dryocoetes striatus Eggers compared with unbaited traps. The addition of the longhorn beetle pheromones, E-fuscumol, or E-fuscumol acetate, to traps baited with spruce blend and ethanol, slightly reduced mean catches of D. striatus but otherwise did not affect catch of any Scolytine species. Baiting traps with ethanol significantly increased mean catches of Anisandrus apicalis (Blandford), Anisandrus dispar (Fabr.), Anisandrus maiche (Kurenzov), Xyleborinus attenuatus (Blandford), Xyleborinus saxesenii (Ratzeburg), Xylosandrus germanus (Blandford), Scolytoplatypus tycon Blandford, and Trypodendron lineatum (Olivier). By themselves, the longhorn beetle pheromones, racemic hydroxyhexan-2-one and racemic hydroxyoctan-2-one, were not attractive to any Scolytine species. However, when added to ethanol-baited traps, hydroxyhexan-2-one lures significantly increased mean catch of S. tycon, hydroxyoctan-2-one lures significantly reduced mean catches of A. maiche and X. attenuatus, and lures of either hydroxyketone significantly reduced mean catch of T. lineatum. The lure treatments that detected the greatest number of species per sampling effort were spruce blend plus ethanol in 2009 (16 Scolytinae species and 13 species of Cerambycidae combined in an eight-trap sample) and hydroxyhexan-2-one plus ethanol in 2010 (20 Scolytinae species and 7 species of Cerambycidae combined in an eight-trap sample). Species accumulation curves did not reach an asymptote for any lure treatment, indicating that many species would go undetected in samples of 8-9 traps per site., Jon D. Sweeney, Peter Silk, Vasily Grebennikov, Michail Mandelshtam., and Obsahuje bibliografii
The outcome of assessments of the biodiversity of a taxonomic group often depend on the sampling method. The choice of an adequate method is especially important for biomonitoring purposes. In this study, the effectiveness of two methods of sampling syrphids (Diptera: Syrphidae) is compared: observation plot method vs. line transect, both sampled by sweep netting. Altogether, 18 meadows were selected in three mountain regions in the Austrian and Swiss Alps. We recorded a significantly higher abundance and richness of syrphids using the observation plot method than the line transect method in 2015. Comparing data for one region recorded in 2015 and 2016, similar results were obtained. Syrphid species assemblages were affected by sampling method in both years. More syrphid species and individuals were recorded using the observation plot method, which makes it more suitable for studies aiming at comparing differences in the numbers of adult syrphids in different grassland habitats., Raja I. Hussain, Ronnie Walcher, David Brandl, Arne Arnberger, Johann G. Zaller, Thomas Frank., and Obsahuje bibliografii
Nově objevený předchůdce současných sépií - egyptosépie (Aegyptosaepia lugeri) spojuje křídové linie dvoužábrých hlavonožců, zastoupených rodem Ceratisepia a třetihorní přímé předchůdce řazené k rodu Belosaepia. Přítomnost znaků křídových předků a pozdějších eocénních zástupců vytváří pozoruhodnou mozaiku, ve které můžeme spatřovat analogii např. se slavným jurským archeopteryxem. Nálezy z paleocénu Egypta poskytly řadu odpovědí na různé otázky evoluce sépiidů, mj. na období a způsob vzniku „rostra“ sépií, jejich paleogeografický původ a biotopy, ve kterých tito hlavonožci vznikali. Nálezy egyptosépií výrazně posouvají vznik přímé linie sépií dále do minulosti, k blízkosti hranice křída/terciér, proslavené velkým vymíráním suchozemských i mořských organismů., Aegyptosaepia (Aegyptosaepia lugeri) - a newly discovered direct ancestor of recent Sepia stock constitutes a link between the Cretaceous coleoid cephalopod Ceratisaepia and the Tertiary Belosaepia. The mixture of morphological features of both, the Cretaceous ancestors and the Eocene descendents creates an interesting mosaic. The Paleocene fossil records from Egypt have provided a lot of answers concerning the sepiid evolution, the period of sepiid “rostrum” origin, palaeobiogeography and the original habitat of these coleoids. The Aegyptosaepia record significantly extended the stratigraphic range of direct Sepia ancestors towards the Cretaceous / Tertiary boundary, an important mass extinction event for marine and non-marine biotas., Martin Košťák., and Obsahuje seznam literatury