How do elevated CO2 and O3 affect the interception and utilization of radiation by a soybean canopy?

Net productivity of vegetation is determined by the product of the efficiencies with which it intercepts light (?_i) and converts that intercepted energy into biomass (?_c). Elevated carbon dioxide (CO₂) increases photosynthesis and leaf area index (LAI) of soybeans and thus may increase ?_i and ?_c; elevated O₃ may have the opposite effect. Knowing if elevated CO₂ and O₃ differentially affect physiological more than structural components of the ecosystem may reveal how these elements of global change will ultimately alter productivity. The effects of elevated CO₂ and O₃ on an intact soybean ecosystem were examined with Soybean Free Air Concentration Enrichment (SoyFACE) technology where large field plots (20‐m diameter) were exposed to elevated CO₂ (～550 μmol mol^?1) and elevated O₃ (1.2 × ambient) in a factorial design. Aboveground biomass, LAI and light interception were measured during the growing seasons of 2002, 2003 and 2004 to calculate ?_i and ?_c. A 15% increase in yield (averaged over 3 years) under elevated CO₂ was caused primarily by a 12% stimulation in ?_c , as ?_i increased by only 3%. Though accelerated canopy senescence under elevated O₃ caused a 3% decrease in ?_i, the primary effect of O₃ on biomass was through an 11% reduction in ?_c. When CO₂ and O₃ were elevated in combination, CO₂ partially reduced the negative effects of elevated O₃. Knowing that changes in productivity in elevated CO₂ and O₃ were influenced strongly by the efficiency of conversion of light energy into energy in plant biomass will aid in optimizing soybean yields in the future. Future modeling efforts that rely on ?_c for calculating regional and global plant productivity will need to accommodate the effects of global change on this important ecosystem attribute.     

Leaf micromorphology inAgathis and its taxonomic implications

This study surveys the micromorphological surface structure of the leaves of the conifer genusAgathis (Araucariaceae) from throughout the range of the genus (Malaysia to New Zealand and Fiji) as seen with the scanning electron microscope. These data confirm that the vegetative parts ofAgathis are taxonomically highly conservative, but suggest the Melanesian and New Zealand elements to be distinctive from those of the rest of the genus, and from one another. Conclusions are compared with those that have been derived from studies based on other characters.     

Variability and genetics of spacer DNA sequences between the ribosomal-RNA genes of hexaploid wheat (Triticum aestivum)

Summary Using restriction enzyme digests of genomic DNA extracted from the leaves of 25 hexaploid wheat (Triticum aestivum L. em. Thell.) cultivars and their hybrids, restriction fragment length polymorphisms of the spacer DNA which separates the ribosomal-RNA genes have been examined. (From one to three thousand of these genes are borne on chromosomes 1B and 6B of hexaploid wheat). The data show that there are three distinct alleles of the 1B locus, designated Nor-B1a, Nor-B1b, and Nor-B1c, and at least five allelic variants of the 6B locus, designated Nor-B2a, Nor-B2b, Nor-B2c, Nor-B2d, and Nor-B2e. A further, previously reported allele on 6B has been named Nor-B2f. Chromosome 5D has only one allelic variant, Nor-D3. Whereas the major spacer variants of the 1B alleles apparently differ by the loss or gain of one or two of the 133 bp sub-repeat units within the spacer DNA, the 6B allelic variants show major differences in their compositions and lengths. This may be related to the greater number of rDNA repeat units at this locus. The practical implications of these differences and their application to wheat breeding are discussed.     

Diet of the Indochinese silvered langur (Trachypithecus germaini) in Kien Luong Karst area,Kien Giang Province

The Indochinese silvered langur (Trachypithecus germaini) is distributed to the west of Mekong River in Cambodia, Lao PDR, Thailand and Vietnam. During a two‐year study, from May 2014 to May 2016, we collected 320.44 hr of behavior, with 17,040 feeding bouts recorded (142 hr) for T. germaini on Chua Hang Karst Mountain, Kien Luong District, Kien Giang Province, Vietnam. Feeding accounted for 45% of the Indochinese silvered langurs’ activity budget. The plant diet of the Indochinese silvered langurs was principally composed of young leaves (58%), followed by mature leaves (9.5%), fruits (22.7%), flowers (4.7%), buds (3.3%), petioles (1.2%), and other (0.5%). A total of 58 plant species were fed on by the silvered langurs, and leaves of eight species (Phyllathus reticulatus, Ficus rumphii, Ficus tinctoria, Ficus microcarpa, Cayratia trifolia, Streblus ilicifolia, Combretum latifolium, and Streblus asper) were fed on throughout the year. P. reticulatus was most frequently eaten (13.9% feeding time, n = 1,733). Food selection differed significantly between months and seasons. The Indochinese silvered langurs ate 27 plant species in the wet season compared with 23 plant species in the dry season. Leaf chemical composition of two food categories, 16 eaten species (with 10 most frequently consumed species and six least consumed species), and four noneaten species, were analyzed. Feeding samples from eaten species in the Indochinese silvered langurs's diet contained lower amounts of condensed tannin, lignin, protein, ash, and lipids, but a higher amount of total sugar compared with samples from noneaten species. Furthermore, the most frequently consumed species contained lower amounts of lignin compared with the less frequently consumed species. Using a generalized linear model with five variables, including neutral detergent fiber (NDF), total sugar, lignin, lipid, and calcium (Ca) indicated that NDF positively correlated and lignin content negatively correlated with feeding records in the diet of these langur.     

Geography of sexual dimorphism in the tooth size of the red fox Vulpes vulpes (Mammalia, Carnivora)

Geographic variation in sexual dimorphism of tooth size was assessed for the red fox Vulpes vulpes (Linnaeus, 1758) across the whole northern range of the species. Twenty-one measurements of tooth size and skull length were taken from 2849 specimens (1577 males and 1272 females) originating from 12 Nearctic and 25 Palearctic localities. The index of sexual dimorphism was calculated as a quotient of the mean measure of certain characters in males by the respective mean in females ( M _m/ M _f). In the whole range, the males were larger than females and mean dimorphism index of tooth size ranged from 1.01 to 1.06. On average, the tooth measurements in males were 3.6% larger than in females. The highest dimorphism was observed in the canines. Dimorphism of tooth size was higher in the Palearctic than Nearctic. Statistically significant differences between regions were found for lengths of C¹, C₁ and M₁. In the Palearctic, higher values of the dimorphism indices were observed particularly in the southern parts of the Eurasian range of the red fox and in Great Britain. For a few metrical traits, sexual dimorphism indices presented significant relations to some geo-climatic variables. The geographic pattern of size dimorphism in the red fox seems to be shaped by sexual selection, intraspecific and interspecific competition and population density.     

The Effect of Leaf Age on Gas Exchange and Malate Accumulation in C3-CAM Plant Marrubium Frivaldszkyanum (Lamiaceae)

For the first time the expression of C₃ and CAM in the leaves of different age of Marrubium frivaldszkyanum Boiss, is reported. With increasing leaf age a typical C₃ photosynthesis pattern and high transpiration rate were found. In older leaves a shift to CAM occurred and the 24-h transpiration water loss decreased. A correlation was established between leaf area and accumulation of malate. Water loss at early stages of leaf expansion may be connected with the shift to CAM and the water economy of the whole plant.