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
Maize plants of CPB2 and CPB8 hybrids were kept under water deficit for 22 d. In the CPB8 hybrid, leaf rolling initiated at the 9th d of water deficit period, while in CPB2 hybrid it was at the 15th d. Both hybrids showed leaf rolling initiation at the same leaf water potential, ΨW of -0.480±0.095 MPa. At leaf rolling initiation, the leaf osmotic potential, ΨS was -0.730±0.085 MPa in CPB8 and 0.630±0.110 MPa in CPB2. The leaf temperature and stomatal conductance were higher in CPB8 than in CPB2. Values of leaf ΨW, ribulose-1,5-bisphosphate carboxylase activity, chlorophyll content, and specific leaf area were similar in both hybrids. Phosphoenolpyruvate carboxylase activity and protein content were lower in the CPB2 hybrid than in CPB8. In both hybrids leaf rolling initiation was associated with: (1) higher leaf temperature, with leaf rolling effect related to leaf temperature reduction, and (2) lower leaf ΨS, related to osmotic adjustment as an additional component of drought-tolerance strategy. and D. Fernandez, M. Castrillo.
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
This article deals with the ex-Capuchin, chaplain and later parson at the Brno parish church of St James, P. Maurus Simonis (*1740-†1815) and his catalogue of the manuscript library which came into being in the Middle Ages, was permanently maintained at the church and only in 1931 did it become a part of the Brno City Archives. The manuscripts – 125 codices – serve as valuable evidence of book culture in medieval Brno. The definitive catalogue was compiled in 1805, while its first "critical" version, which does not include all manuscripts, dates from 1802. On the evidence of numerous specimens, our paper analyses the way of describing of external features – watermarks, writing, decoration and binding – as well as the content of individual codices, and it compares the work of P. Simonis with the previously unofficial conclusions of the modern catalogue which is currently at the printers.