Co víme o květeně Brna? S jakými údaji můžeme pracovat a jaká je metodika sběru floristických údajů? Těmito tématy se zabývá článek shrnující dosavadní poznání květeny města Brna., What do we know about flora in the city of Brno? Which data are available and which methods were used for floristic data sampling? These are the topicscovered in the summary of recent findings on the flora in the city of Brno., and Zdeňka Lososová, Kateřina Šumberová, Lubomír Tichý, Jiří Danihelka, Marie Vymazalová.
Plant invasions may be limited by low radiation levels in ecosystems such as forests. Lantana camara has been classified among the world's 10 worst weeds since it is invading many different habitats all around the planet. Morphological and physiological responses to different light fluxes were analyzed. L. camara was able to acclimate to moderately shaded environments, showing a high phenotypic plasticity. Morphological acclimation to low light fluxes was typified by increasing leaf size, leaf biomass, leaf area index and plant height and by reduced stomatal density and leaf thickness. Plants in full sunlight produced many more inflorescences than in shaded conditions. Physiological acclimation to low radiation levels was shown to be higher stomatal conductance, higher net photosynthetic rates and higher efficiency of photosystem II (PSII). L. camara behaves as a facultative shade-tolerant plant, being able to grow in moderately sheltered environments, however its invasion could be limited in very shady habitats. Control efforts in patchy environments should be mainly directed against individuals in open areas since that is where the production of seeds would be higher and the progress of the invasion would be faster. and J. Carrión-Tacuri ... [et al.].
This study measured individual leaf area expansion rate and leaf net photosynthetic rate (PN) of meadow bromegrass (Bromus riparius Rehm.), smooth bromegrass (Bromus inermis Leyss.) and hybrid bromegrass (B. riparius × B. inermis). Smooth bromegrass expanded individual leaf area 1.5 times faster than meadow bromegrass and hybrid bromegrass. PN was highest in smooth bromegrass, intermediate in hybrid bromegrass, and lowest in meadow bromegrass. Rapid growth of meadow bromegrass following defoliation compared to smooth bromegrass and hybrid bromegrass could not be explained by higher rates of these measured characteristics. and B. Biligetu, B. Coulman
Leaf area is one of the most important parameter for plant growth. Reliable equations were offered to predict leaf area for Zea mays L. cultivars. All equations produced for leaf area were derived as affected by leaf length and leaf width. As a result of ANOVA and multiregression analysis, it was found that there was a close relationship between actual and predicted growth parameters. The produced leaf-area prediction model in the present study is LA =
a + b L + c W + d LZ where LA is leaf area, L is leaf length, W is maximum leaf width, LZ is leaf zone and a, b, c, d are coefficients.
R2 values were between 0.88-0.97 and standard errors were found to be significant at the p<0.001 significance level. and F. Oner ... [et al.].
Drought significantly constrains higher yield of alfalfa (Medicago sativa L.) in arid and semiarid areas all over the world. This study evaluated the responses of leaf cuticular wax constituents to drought treatment and their relations to gas-exchange indexes across six alfalfa cultivars widely grown in China. Water deficit was imposed by withholding water for 12 d during branching stage. Cuticular waxes on alfalfa leaves were dominated by primary alcohols (41.7-54.2%), alkanes (13.2-26.9%) and terpenes (17.5-28.9%), with small amount of aldehydes (1.4-3.4%) and unknown constituents (4.5-18.4%). Compared to total wax contents, the wax constituents were more sensitive to drought treatment. Drought decreased the contents of primary alcohol and increased alkanes in all cultivars. Alkane homologs, C25, C27, and C29, were all negatively correlated with photosynthetic rate, transpiration rate, stomatal conductance, and leaf water potential. Under drought conditions, both stomatal and nonstomatal factors were involved in controlling water loss from alfalfa leaves. No direct relationship was observed between wax contents and drought resistance among alfalfa cultivars. An increase in alkane content might be more important in improving drought tolerance of alfalfa under water deficit, which might be used as an index for selecting and breeding drought resistant cultivars of alfalfa., Y. Ni ... [et al.]., and Obsahuje bibliografii