Bewertung der nährstoffgehalte im statischen düngungsversuch bad lauchstädt

Der Statische Düngungsversuch Bad Lauchstädt wurde 1902 auf Löß‐Schwarzerde (21% Ton, 8,7°C Jahresdurchschnittstemperatur und 484 mm Jahresniederschlag) angelegt. Nach 96 Versuchsjahren wurde im Jahre 1998 auf Schlag I von allen Varianten der Gehalt an Gesamt‐P, doppellaktatlöslichem P und K, Mg, Cu, Zn, Mn und pH‐Wert bestimmt. Die P‐Entzüge liegen zwischen 9 kg/ha.a (ungedüngt) und 30 kg/ha.a. Die Gehalte an Gesamt‐P liegen zwischen 47 und 100 mg/100g Boden. Mit 10t/ha.a Stalldung wird bereits eine optimale Zufuhr an den Nährstoffen P, K und Mg erreicht bzw. überschritten. Mg und Zn reagieren deutlich auf die Stalldunggabe, weniger Cu. Die pH‐Werte liegen mit Kalkdüngung im Mittel aller Prüfglieder bei 7,3 (Spannweite 7,2 bis 7,5), ohne Kalk bei 6,6 (6,3–7,3). Stalldung wirkt nicht auf die pH‐Werte. Es besteht eine deutliche Wechselwirkung zwischen pH‐Wert und Mn. Mit Kalk wird Mn festgelegt und liegt zwischen 27 und 40 ppm, ohne Kalk zwischen 32 und 100 ppm.     

Using otolith microchemistry to reconstruct habitat use of American eels Anguilla rostrata in the St. Lawrence River–Lake Ontario system

Catadromy among freshwater eels is increasingly recognised as being facultative, with some individuals carrying out growth exclusively in brackish or coastal marine waters, or switching between brackish or marine waters and freshwater habitats. In an attempt to reconstruct habitat use of yellow‐stage American eels in a large river‐lake ecosystem, trace element line scans were obtained, using LA‐ICP‐MS, from the otoliths of 110 eels sampled at various locations throughout the St. Lawrence River–Lake Ontario (SLRLO) system. Elemental profiles for strontium (Sr), barium (Ba), manganese (Mn) and magnesium (Mg) enabled us to distinguish three chemical signatures that appear to represent three distinct habitats within the SLRLO. Of these, one was shown to likely correspond to the brackish estuary (high strontium values). The other two signatures, characterised by low strontium but variable concentrations of barium and manganese, may correspond to habitats within the main‐stem St. Lawrence River and one or more of its tributaries. Most (78%) of the switches among habitats occurred within the first four years after recruitment suggesting an increasing likelihood for eels to maintain residence in one habitat as they grow older. This suggests that tributaries may provide important habitats for American eels during the first several years after recruiting to the SLRLO. In addition, our results suggest that a small proportion American eels in the SLRLO can undertake movements on the order of at least 200 km during the early growth stage. This information has important implications for the management and conservation of this species in the system.     

Towards effective soybean seed systems in Benin: Current situation and prospects for production and delivery of good quality seed

Facilitating farmers’ access to quality seed requires proper understanding of the functioning of seed systems. This study aimed at analyzing soybean (Glycine max [L.] Merr.) seed systems in Benin to pave the way for strengthening this sector. The research approach consisted of desk research, focus group discussions, individual interviews and validation workshop with stakeholders involved in soybean seed systems. Our findings revealed that despite the existence of an institutional and organizational framework, the formal soybean seed system is not at all functioning. Farmers mainly relied on informal seed system through self-saved seed and seed purchase in the markets. There is an emerging soybean seed system led by NGOs and farmers’ organizations. Current soybean seed systems are ineffective in timely supplying desired soybean varieties to farmers. Creation of enabling environment to attract private investment and develop local seed businesses is proposed along with new organizational arrangements among stakeholders. Farmers’ training in seed production, processing and managerial skills, as strategy to improve informal seed system, are proposed to strengthen local seed business. Farmers’ organizations have a critical role to play, as they serve as intermediary between their members and seed producers. Information and Communication Technology (ICT) could be exploited not only to promote improved seeds but also to ensure traceability in the system. Quality Declared Seed could be the most adapted quality insurance scheme in remote areas. The proposed arrangements among stakeholders in the seed systems in this study could be applied to legume crops other than soybean.     

Heart rate variability in relation to stress in the Asian elephant (Elephas maximus)

This study describes a safe, reliable, and accessible means to measure heart rate (HR) and HR variability (HRV) and evaluates the use of HRV as a physiological correlate of stress in the Asian elephant. A probabilistic model indicates that HRV measurements may adequately distinguish between stressed and non-stressed elephants.     

The morphology–diet relationship and its role in the coexistence of two species of annual fishes

Annual fishes, which inhabit temporary pools with extremely limited habitat complexity and niche availability, display remarkable sexual dimorphism, rapid growth, and enormous investment into reproduction, all traits associated with high energy requirement. This study tests three hypotheses for two syntopic annual fishes (Austrolebias minuano and Cynopoecilus fulgens) found in six wetlands of southern Brazil: (i) considerable morphological differences result in low dietary overlap, (ii) sexual dimorphism in both species leads to intraspecific diet segregation, and (iii) dietary richness increases during ontogenetic development, and is narrower in C. fulgens than A. minuano due to morphological limitations imposed by reduced size. The diet of 82 A. minuano and 211 C. fulgens individuals was analyzed over two annual cycles. The morphology was characterized by 26 measurements covering the entire body of both species. There was no evidence of morphological specialization related to food competition and the diet of A. minuano and C. fulgens showed high overlap. High food availability, high predator abundance, and high connectivity of adjacent wetlands are likely the main mechanisms allowing coexistence of both species. Within species, sexual dimorphism did not result in a decrease in dietary overlap, which reinforces the idea that morphological differences between the sexes did not evolve as a mechanism to decrease food competition. Large A. minuano did not have a more diverse diet than the smaller C. fulgens; however, increase in body size allowed both species to ingest larger prey. Morphological variability in both species was mainly related to ontogenetic development and reproduction.     

Spring home ranges of white bass in irrigation reservoirs of the Republican River Basin, Nebraska

Abstract –  Fishery biologists have documented small home ranges, relative to available habitat, for many littoral freshwater fishes. Home ranges for pelagic species, such as white bass Morone chrysops , are generally not well described, yet are thought to be large. We studied white bass movement using acoustic telemetry in two irrigation reservoirs of the Republican River basin in south-western Nebraska. Acoustic transmitters were implanted in fall of the previous year and tracking occurred a minimum of once per week throughout spring (mid-March to May) 2007 and 2008. Linear home ranges were calculated from observed locations of individual fish. Twelve of the twenty-seven tagged fish with at least five locations exhibited localised home ranges throughout the spring whereas the remaining fish exhibited home ranges extending across large portions of each reservoir. Home range size was not correlated with fish size or condition.     

Characterization of pea accessions by SRAP's markers

Sequence-related amplified polymorphism (SRAP) and morphological markers to estimate the genetic relations among forty pea varieties (Pisum sativum L.) were studied. Data on 15 morphological traits were collected and analyzed. A total of 162 polymorphic SRAP's bands were scored using seven combinations of primers. Cluster analysis and both principal component and principal coordinate analysis were carried out. The varieties were grouped in four clusters through procrustes generalized analysis. Relationships among varieties revealed by molecular markers were significantly correlated with those based on the agronomic traits, suggesting that the two systems give similar estimates of genetic relations among the varieties. Parents selection depend on the specific objectives in further breeding programs.