The effects of soil and water contamination by lead (Pb) and the consequences on plant growth and yield are of great concern worldwide. Limits of the Pb concentration in water have been established by governmental institutions but these differ from each other. In this study, Lactuca sativa (var. Reine de Mai) plants were exposed to low Pb(NO3)2 doses (0.05-20 mg L-1), including the recommended limit values for irrigation water by the Food and Agriculture Organization (FAO). After 28 d of exposure, lettuce plants did not present visible morphological alterations or growth impairment, but CO2 assimilation rate (PN), photochemical quenching, and effective quantum efficiency of PSII were negatively affected, while intercellular CO2 concentration, stomatal conductance, or transpiration rate were not influenced. Our results suggested that limitations on photosynthesis occurred from different reasons than due to the decrease of internal CO2 availability, alterations of photophosphorylation, and/or electron transport rate. Thus, this lettuce cultivar showed photosynthetic susceptibility to low doses of Pb, even at lower concentrations than those maximal allowed for irrigation water by FAO. Furthermore, PN seemed to be the most sensitive biomarker for evaluation of Pb susceptibility., S. Silva, G. Pinto, C. Santos., and Obsahuje bibliografii
Ostrov Madagaskar patří z pohledu taxonomů i ochranářů mezi nejzajímavější místa světa. A zvláště mezi palmami, v čeledi Arecaceae patří mezi významná vývojová centra - nesmírně bohatá a zároveň velmi zranitelná. Z Madagaskaru je dosud popsáno 203 druhů palem v 17 rodech, což je téměř trojnásobek oproti celé Africe. Přitom pouhých 7 druhů má větší areály, zbývající druhy jsou madagaskarskými endemity. První díl dvoudílného seriálu představuje klimatické, geografické a vegetační poměry ostrova. Zvláštní kapitolu zasluhuje i historie tamního palmového výzkumu., In the eyes of taxonomists and nature conservationists, Madagascar is one of the most interesting areas in the world, particularly with regard to palms (Arecaceae), as these form an important evolutionary centre - very rich and yet at the same time fragile. 203 palm species in 17 genera has been described so far, which is three times more than in Africa. And only 7 species have wider distribution outside Madagascar, the rest being endemics of the island. The first part of this two-volume article describes the climatic, geographic and vegetation characteristics of the island. The history of palm research in Madagascar is also mentioned., and Vlastik Rybka, Romana Rybková.
Madagaskarské palmy tvoří necelou desetinu celkového světového palmového bohatství co do počtu rodů i druhů, což potvrzuje význam ostrova pro tuto čeleď. Po prvním dílu představujícím vegetační poměry ostrova a historii palmového výzkumu přibližujeme ve druhém dílu jednotlivé palmové rody. U větších rodů Ravenea a Dypsis je podán rámcový přehled druhové rozmanitosti, u malých rodů je přehled úplný. Pozornost věnujeme i ohrožení madagaskarských palem a jeho hlavním příčinám., Palm species of Madagascar encompass almost one tenth of the entire palm (Arecaceae) richness throughout the world. It confirms the importance of the island for palms. While the first part of the series described the vegetation characteristics along with the history of palm research, the second part introduces all the palm genera of Madagascar. Smaller genera are presented in full scope, and some interesting species from the larger genera Dypsis and Ravenea are highlighted. Conservation status and contemporary threats to the palms of Madagascar are also covered., and Vlastik Rybka, Romana Rybková.
Městské parky, dřeviny a byliny kolem cest a v zahradách. Za vznikem tohoto historického dědictví stáli britští obchodníci s vínem a cukrem z cukrové třtiny, kteří v 18. a 19. stol. zakládali zahrady kolem svých farem a sídel. Později se izolované zahrady spojily a vznikaly první větší zahradní celky kolem hotelů. Ve 20. stol. se zakládaly parky již přístupné veřejnosti. Vznikaly tematické sbírky tropických rostlin, kaktusů a jiných sukulentů. Parků, zahrad a ostatních zelených ploch je jen v hlavním městě Funchalu přes 450 ha. Téměř každý dům, hotel a restaurace má zahrádku. Jsou zde k vidění i keře a stromy prakticky z celého světa. Většinu z nich lze v našich podmínkách pěstovat pouze ve sklenících. Exotické rostliny byly vysazeny i ve volné krajině. Některé druhy jsou velmi agresivní a nekontrolovaně se šíří po ostrovech., In the 18th and 19th centuries, British merchants set up gardens around their settlements. Later, larger gardens appeared around hotels, and in the 20th century, parks were established, maintaining also collections of tropical plants or succulents. Almost 450 ha of these green spaces in the capital city of Funchal host trees and bushes from all over the world. Exotic species were planted even in open countryside. Some of them are invasive, spreading rapidly across the islands., and Miloslav Kuklík, Václav Zelený.
Plant response to the combination of two or more abiotic stresses is different than its response to the same stresses singly. The response of maize (Zea mays L.) photosynthesis, growth, and development processes were examined under sunlit plant growth chambers at three levels of each day/night temperatures (24/16°C, 30/22°C, and 36/28°C) and UV-B radiation levels (0, 5, and 10 kJ m-2 d-1) and their interaction from 4 d after emergence to 43 d. An increase in plant height, leaf area, node number, and dry mass was observed as temperature increased. However, UV-B radiation negatively affected these processes by reducing the rates of stem elongation, leaf area expansion, and biomass accumulation. UV-B radiation affected leaf photosynthesis mostly at early stage of growth and tended to be temperature-dependent. For instance, UV-B radiation caused 3-15% decrease of photosynthetic rate (PN) on the uppermost, fully expanded leaves at 24/16°C and 36/28°C, but stimulated P N about 5-18% at 30/22°C temperature. Moreover, the observed UV-B protection mechanisms, such as accumulation of phenolics and waxes, exhibited a significant interaction among the treatments where these compounds were relatively less responsive (phenolics) or more responsive (waxes) to UV-B radiation at higher temperature treatments or vice versa. Plants exposed to UV-B radiation produced more leaf waxes except at 24/16°C treatment. The detrimental effect of UV-B radiation was greater on plant growth compared to the photosynthetic processes. Results suggest that maize growth and development, especially stem elongation, is highly sensitive to current and projected UV-B radiation levels, and temperature plays an important role in the magnitude and direction of the UV-B mediated responses., S. K. Singh, K. R. Reddy, V. R. Reddy, W. Gao., and Obsahuje bibliografii
In China, narrow-wide row planting pattern has been advocated for maize (Zea mays L.) production. However, no previous study has clearly elucidated the complexity of factors affecting maize canopy such as the microclimatic factors, and the effect of photosynthesis in narrow-wide row planting pattern. The current study was undertaken to identify the planting patterns that influence microclimatic conditions and photosynthesis of two maize cultivars (Beiyu288 and Xianyu335) grown in three planting patterns: narrow-wide rows of (1) 30 cm + 170 cm (P1, 6.4 plants m-2), and (2)
40 cm + 90 cm (P2, 6.4 plants m-2), and (3) uniform row of 65 cm (CK, conventional row as control, 6.4 plants m-2). Light interception, temperature, relative humidity (RH), CO2 concentration, and leaf photosynthesis within the canopy were measured in each planting treatment at the grain-filling stage. The net photosynthetic rate
(PN), intercellular CO2 concentration (Ci), stomatal conductance
(gs), transpiration rate (E), and temperature of the narrow-wide row exceeded that of the conventional row. The CO2 concentration and RH of the narrow-wide row were lower than CK by 50 cm strata. The narrow-wide row had a more uniform light intercepted at the whole canopy profile. The results of the current study suggest that
narrow-wide row-planting pattern has a positive effect on canopy microclimate factors and promotes photosynthesis., T. D. Liu, F. B. Song., and Obsahuje bibliografii