Winter wheat (Triticum aestivum L.) cultivars Yangmai 9 (water-logging tolerant) and Yumai 34 (water-logging sensitive) were subjected to water-logging (WL) from 7 d after anthesis to determine the responses of photosynthesis and anti-oxidative enzyme activities in flag leaf. At 15 d after treatment (DAT), net photosynthetic rate under WL was only 3.7 and 8.9 µmol(CO2) m-2 s-1 in Yumai 34 and Yangmai 9, respectively, which was much lower than in the control. Ratios of variable to maximum and variable to initial fluorescence, actual photosynthetic efficiency, and photochemical quenching were much lower, while initial fluorescence and non-photochemical quenching were much higher under WL than in control, indicating damage to photosystem 2. WL decreased activities of superoxide dismutase and catalase in both cultivars, and activity of peroxidase (POD) in Yumai 34, while POD activity in Yangmai 9 was mostly increased. The obvious decrease in the amount of post-anthesis accumulated dry matter, which was redistributed to grains, also contributed to the grain yield loss under WL. and W. Tan ... [et al.].
The effects of CO2 concentration on spore germination, growth, and net photosynthetic rate (PN) of gametophytes of a tropical epiphytic fern, Pyrrosia piloselloides, were investigated over a 100-d period. Increasing CO2 concentration stimulated spore germination and enhanced gametophytic growth. The appearance of sexual organs and formation of sporophytes were accelerated with higher CO2 during growth. Radiant energy saturated PN and dark respiration rate also increased with increasing CO2 concentrations during growth. and Bee-Lian Ong, C. K-K. Koh, Yeow-Chin Wee.
Quantitative data are presented on the spatial distribution of metacercariae of the digenean trematode Diploslomum phoxini (Faust, 1918) in the brains of minnows, Phoxinus phoxinus (Linnaeus, 1758), from two Scottish populations. Sequential examination of serial histological sections revealed metacercariae to be unevenly distributed throughout the brain, aggregating in specific regions including the cerebellum, the medulla oblongata and the optic lobes. In addition, a number of metacercariae were found in the anterior part of the spinal cord. The inferior lobe of the cerebellum, pituitary, olfactory lobes and olfactory bulbs were largely free of metacercariae. Reasons for the uneven distribution of metacercariae within the brains of infected minnows are discussed, including the possibility that the parasite may have evolved to enhance its transmission to subsequent hosts by aggregating in regions known to be important in the control of the host’s antipredator responses.