Analysis of Chlorophyll Fluorescence by Means of Noisy Light

Linearization is an efficient means of detecting individualcomponents in complex fluorescence induction curves. In a previousinvestigation based on sine-waves (Hansen, Kolbowski, and Dau,1987) the components related to the plastoquinone pool, thehigh-energy state of the thylakoid membrane and the state 1-state2 transition controller could be identified. In this paper,binary noise is used as an alternative input signal which canalso allow linearization by mathematical tools. Comparison withexperiments using sine-waves shows that curve-fitting of thenoise experiments yields the same data as the sine-wave analysis.Further, some additional components were revealed as labelledby the related time-constants whose values depended on lightintensity (e.g. 5, 15, 20, 70, 85, 550 s for spinach at 2.5W m^–2). The advantages of noise analysis are a shorter measuring time and the availability ofan on-line criterion which indicates when a sufficient signal-to-noiseratio is reached. Key words: Chlorophyll fluorescence, correlation functions, linearization, noise, spinach, time-constants     

Correlations between Haustoria Formation and Parasitic Development in Orthocarpus purpurascens (Scrophulariaceae)

Three lines of evidence correlate the parasitic performane ofOrthocarpus purpuruscens Benth. with numbers of haustoria produced:(i) the pattern of variation in numbers of haustoria producedin agar culture with different chemical stimuli correspondsclosely to the variation pattern of parasite vigour producedby a range of host plants; (ii) the progeny of plants demonstratingvigorous growth with hosts produce significantly more haustoriathan progeny from parents exhibiting weak parasitic development;(iii) conversely, seedlings that produce high numbers of haustoriain agar culture grow significantly better when transplantedwith hosts than do seedlings with low numbers of haustoria.Haustoria-forming potential is heritable, but highly influencedby environmental factors. Potential number of haustoria is aproduct of the concentration and/or quality of haustoria inducingstimuli, and the parasite's individual ability to respond. Intra-populationdifferences in parasitic development appear to be largely dueto the quantity rather than the quality of substrates receivedfrom host plants. haustoria, Orthocarpus purpurarcens, parasitic development     

Pehr Osbeck's collections and Linnaeus's Species Plantarum (1753)

On the basis of Osbeck's and Linnaeus's correspondence in 1752, which is briefly discussed, Osbeck's conveyance of his collections, and Linnaeus's subsequent incorporation of the new species into his Species Plantarum , are illustrated. A means of referring specimens in Linnaeus's herbaria to Osbeck's collections is provided. Finally an approximate date for the start of the printing of Species Plantarum is suggested.     

Unravelling the genetic complexity of sorghum seedling development under low‐temperature conditions

Sorghum is a promising alternative to maize for bioenergy production in Europe; however, its use is currently limited by poor adaptation to low temperatures during and after germination. We collected multi‐trait phenotype data under optimal and suboptimal temperatures in a genetically diverse recombinant inbred line (RIL) mapping population showing contrasting segregation patterns for pre‐ and post‐emergence chilling tolerance. Germination, emergence, seedling development, root architecture and seedling survival were assessed in two different seedlots. Emergence and root establishment were found to be the key determinants of development and survival under chilling stress. Highly interactive epistatic quantitative trait loci (QTL) hotspots, including a previously unknown QTL on Sb06 with a significant effect on prolonged chilling survival, were found to regulate different physiological mechanisms contributing to maintenance of growth and development despite the chilling temperatures. The major QTL regions harbour promising candidate genes with known roles in abiotic stress tolerance. Identification of loci in the QTL hotspot regions conferring maintenance of cell division and growth under early chilling stress represents a promising step towards breeding for successful establishment of sorghum in temperate climates.     

RECENT BIOACOUSTIC PUBLICATIONS—from 1991 and a few from 1990 and 1989

ABSTRACT

The focus of this study was to determine whether individual vocal identification of Scops Owls Otus scops was possible and if there was a stability of the hoot-calls over a short time period in the same individuals. Spontaneous vocalizations of 13 owls were recorded in 2004 in Southern Tuscany, Italy. Visual analysis of spectrograms and quantitative multivariate analysis of six vocal features showed marked individual differences. In some owls a repertoire of two different hoot types was found. In 2005, 10 Scops owls were recorded three times in the same breeding season (2 hours and 10 days after the first session). Statistical analysis of data showed that 60% of owls did not change call features over time. However a slight but significant variability between successive vocal performances of the same owl was found in 40% of cases. This variability may decrease the recognition power by acoustic analysis. To overcome this obstacle I suggest a multi step qualitative/quantitative approach. A Difference Index (DI) was calculated to set a threshold between the slight intra-individual and the very high inter-individual variability. This method allowed the recognition of calls of each owl recorded over time in 2005.     

Relationship of Hypochaeris salzmanniana (Asteraceae, Lactuceae), an endangered species of the Iberian Peninsula, to H. radicata and H. glabra and biogeographical implications

Hypochaeris salzmanniana DC. (Asteraceae, Lactuceae) is an endangered species on the Iberian Peninsula, known from only eight coastal populations. Most authors have treated it as a variety, subspecies or simply as a synonym of H. glabra L. On the basis of morphological and cytological characters, Talavera recently separated H. salzmanniana (2n = 8) from H. glabra (2n = 10). Material of H. salzmanniana, H. glabra and H. radicata was collected from Spain, Italy, Sicily and Tunisia in order to assess taxonomic status and population relationships. Amplified Fragment Length Polymorphism (AFLP) analysis revealed three well-differentiated species. A close relationship between H. salzmanniana and H. radicata is also confirmed by AFLP analysis and chromosome number (2n = 8), morphology, and rDNA localization (FISH, fluorescence in situ hybridization). Hypochaeris salzmanniana and H. radicata share three fixed diagnostic AFLP fragments out of 348 fragments scored. The population structure of H. salzmanniana reveals distinct groups in southern Spain that are separated geographically. High differentiation among a western (Conil to Zahara), an intermediate (Punta Paloma and Los Algarbes) and an eastern (Algeciras and La Línea) group may reflect ancient separation. Population sizes and genetic compatibility differ greatly among populations and can be used to explain levels of within-population genetic diversity, together with recent documented loss of habitats resulting from tourist developments. Population structures of H. radicata and H. glabra show a similar geographical patterning: strongly differentiated populations from the Betic Cordillera and from the Iberian Massif, which are separated at present by the Guadalquivir river. Geological events at the end of the Tertiary (Tortonian–Messinian Miocene) might help explain patterns of differentiation in these three species of sect. Hypochaeris. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society, 2004, 146 , 79–95.