Early interspecific dynamics,dry matter production and nitrogen use in Kernza (Thinopyrum intermedium) – alfalfa (Medicago sativa L.) mixed intercropping     

Shoujiao Li  Ana Barreiro  Erik Steen Jensen  Yingjun Zhang 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2020,70(2):165-175

ABSTRACT

The global interest in growing perennial grain crops such as intermediate wheatgrass (Thinopyrum intermedium) (Kernza) for production of food and feed is increasing. Intercropping Kernza with legumes may be a sustainable way of supplying nitrogen to soil and associated intercrop. We determined the competitive interactions between intercropped Kernza (K) and alfalfa (Medicago sativa L.) (A) under three inorganic nitrogen (N) rates N0, N1, N2 (0, 200, 400 kg ha^?1) and five species relative frequencies (SRF) (100%K:0%A, 75%K:25%A, 50%K:50%A, 25%K:75%A and 0% K:100%A) in mixed intercrops (MI) in a greenhouse pot experiment. After 11 weeks of growth. Kernza dry matter yield (DM) and N accumulated (NACC) were low, but alfalfa DM and NACC high at 0 kg N ha^?1. 200 and 400 kg N ha^?1 fertiliser application increased the competitive ability (CA) of Kernza and reduced the CA of alfalfa. SRF had large impacts on alfalfa DM, NACC and NFIX only at 0 kg N ha^?1 fertiliser, and insignificant impacts on Kernza at all N fertiliser levels, indicating that adjustment of SRF may not be an effective way to modulate the interspecific competition of Kernza. Further research on the other factors that influence the interspecific competition are warranted.  相似文献   

Use of endoscopy for gender and ovarian stage determinations in Russian sturgeon (Acipenser gueldenstaedtii) grown in aquaculture     

Avshalom Hurvitz  Karen Jackson  Gad Degani  Berta Levavi-Sivan   《Aquaculture (Amsterdam, Netherlands)》2007,270(1-4):158-166

The Russian sturgeon (Acipenser gueldenstaedtii) is native to the Caspian Sea, the Black Sea and the Azov Sea. It used to breed in the main incoming rivers, until dam construction in the mid 20th century blocked upriver spawning migration. Aquaculture of Russian sturgeon has only recently begun, prompted by their declining populations in natural habitats and the rise in meat and caviar prices. However, information on their gonadal development and puberty under culture conditions is incomplete.

Because sturgeons have no external sexual dimorphism and there are no external markers for sexing, internal examination of the gonads must be employed for gender identification as well as to monitor their development. The present study describes endoscopic and histological observations of the gonads of young Russian sturgeons aimed at identifying gender and monitoring ovarian developmental stage in females up to the age of 6 years, when they enter their first puberty cycle, as well as at 7 years of age, when they have completed vitellogenesis, under culture conditions. This information, as related to fish age and size, is of vital importance to commercial farming of Russian sturgeon for caviar production and reproduction.

For gonadal observations in both sexes, we used an endoscopic system consisting of a 4 mm, 14 cm long cystoscope sheath incorporated with fiber-optic light transmission, connected to a halogen cold light source and a miniature videocamera with a control unit attached to a color monitor. This system allowed us viewing of the fish's abdominal organs, and to save pictures of selected areas of the gonads on a computer as the fish's personal record. Ovarian biopsies were taken in parallel for histology at typical stages of gonadal development.

Gender could be identified with this system as early as at 3 years of age and the sex ratio under culture conditions of females, males and unidentified gender were 55, 40 and 5%, respectively.

Not only did large differences occur in the developmental stages of female of the same age group, but also ovarian development was highly asynchronous at the early vitellogenic stages. In late vitellogenesis, at the “gray egg” stage (1600–2600 μm diameter), the oocytes were quite regular in size and color, and remained so until the final stages of maturity.

Our study suggests that endoscopy is an efficient method for both gender identification at an early age, and for determination of gonadal development stage in sturgeon aquaculture. The ability to see the whole intact gonads of anesthetized fish can reveal important management and research information, with minimal damage or stress to the fish.  相似文献   

Changes in Cd,Cu, Ni,Pb and Zn Fractionation and Liberation Due to Mussel Shell Amendment on a Mine Soil     

David Fernndez‐Calvio  Lorena Prez‐Armada  Laura Cutillas‐Barreiro  Remigio Paradelo‐Núez  Avelino Núez‐Delgado  María J. Fernndez‐Sanjurjo  Esperanza lvarez‐Rodriguez  Manuel Arias‐Estvez 《Land Degradation \u0026amp; Development》2016,27(4):1276-1285

Mining activities are related to relevant environmental pollution issues that should be controlled. We used sequential extractions to fractionate Cd, Cu, Ni, Pb and Zn retained on unamended or mussel shell‐amended mine soil samples, all of them treated with a mixture of the five heavy metals (total metal concentration of 1·57 mmol L⁻¹), after 1, 7 and 30 days of incubation. In addition, we used the stirred flow chamber technique to study the release of each of the five heavy metals from these different unamended and shell‐amended soil samples. The results indicate that the shell amendment caused a decrease in the most soluble fraction, while increasing the most recalcitrant (least mobile) fraction. With equivalent implications, the stirred flow chamber experiments showed that mussel shell amendment was associated to a decrease in heavy metal release and increased retention. The highest mussel shell dose and incubation time caused the most relevant changes in pH values and thus in metal retention, also indicating the importance of pH modifications in the mechanism of retention acting in the amended samples. In view of these results, the use of mussel shell amendment can be encouraged to increase heavy metal retention in acid mine soils, in order to minimise risks of environmental pollution. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Experimental repetitive quantum error correction     

Schindler P  Barreiro JT  Monz T  Nebendahl V  Nigg D  Chwalla M  Hennrich M  Blatt R 《Science (New York, N.Y.)》2011,332(6033):1059-1061

The computational potential of a quantum processor can only be unleashed if errors during a quantum computation can be controlled and corrected for. Quantum error correction works if imperfections of quantum gate operations and measurements are below a certain threshold and corrections can be applied repeatedly. We implement multiple quantum error correction cycles for phase-flip errors on qubits encoded with trapped ions. Errors are corrected by a quantum-feedback algorithm using high-fidelity gate operations and a reset technique for the auxiliary qubits. Up to three consecutive correction cycles are realized, and the behavior of the algorithm for different noise environments is analyzed.  相似文献   

What is a whale?     

Berta A 《Science (New York, N.Y.)》1994,263(5144):180-181

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Skeleton of the Oldest Known Pinniped, Enaliarctos mealsi     

Berta A  Ray CE  Wyss AR 《Science (New York, N.Y.)》1989,244(4900):60-62

A nearly complete skeleton of the archaic pinniped Enaliarctos, found in late Oligocene or early Miocene rocks (approximately 23 million years old) of California, provides new evidence on the origin of pinnipeds. Enaliarctos retains many primitive features expected in the hypothesized common ancestor of pinnipeds. Skeletal modifications seen in Enaliarctos document swimming adaptations and indicate that pinnipeds primitively used the axial skeleton and both fore and hindflippers as sources of propulsion. Elongate hindlimbs with prominent bony processes (reflecting powerful musculature) suggest that Enaliarctos was more active on land than modern pinnipeds.  相似文献   

Origin of lead in andean calc-alkaline lavas, southern peru     

Tilton GR  Barreiro BA 《Science (New York, N.Y.)》1980,210(4475):1245-1247

Lead isotope data from Quaternary andesitic lavas of the Arequipa and Barroso groups of southern Peru and from regional Precambrian granulitic gneisses reveal a lead component in the lavas from the gneisses. The lava leads can be accounted for by two-component mixtures of lead from mantle and lower crustal sources, although the mixing process need not have occurred in the lower crust.  相似文献   

Weeds,aphids, and specialist parasitoids and predators benefit differently from organic and conventional cropping of winter cereals     

Berta Caballero-López  José M. Blanco-Moreno  Nicolás Pérez-Hidalgo  José M. Michelena-Saval  Juli Pujade-Villar  Emilio Guerrieri  José A. Sánchez-Espigares  F. Xavier Sans 《Journal of pest science》2012,85(1):81-88

The aphid–natural enemy interaction in winter wheat fields constitutes a complex system that has been frequently studied because of its implication for biological control. However, not all of the aphids living in cereal fields are crop pests, as there are also aphids living on weeds that may serve as alternative hosts or prey for aphid parasitoids or predators. In this context, a concomitant survey of the plant and insect communities was conducted to understand how different plant communities affect the abundance and richness of aphids and the interactions with their natural enemies. The plant community was split into functional groups (grasses, legumes and forbs), and the aphid community was divided into feeding groups according to their host preferences (specialists in grasses or forbs). The grass aphids, which dominated the total aphid catches, responded positively to grass cover, which was particularly enhanced in the conventional fields. Conversely, the forb aphids, which mainly conditioned the total species richness of the aphids, were closely correlated with the local abundance of legumes. The system of cereal aphid-parasitoids was enhanced in the conventional fields, where the abundance of grasses was higher, whereas the legumes of the organic fields indirectly played a key role in enhancing the richness of the parasitoids and the abundance of predators. Our findings indicate that a bottom-up effect exists throughout the plant community, aphids, and aphidophagous insects and that plant community characteristics should be considered to better understand cereal aphid control.  相似文献   

Leaf structure and function of sweet cherry tree (Prunus avium L.) cultivars with open and dense canopies     

Berta Gonalves  Carlos M. Correia  Ana Paula Silva  Eunice A. Bacelar  Alberto Santos  Jos M. Moutinho-Pereira 《Scientia Horticulturae》2008,116(4):381-387

Variations in morpho-anatomy, chemical composition, gas exchange and stem water potential (Ψ_stem) were studied in leaves of Prunus avium L. cultivars with different growth habit: Burlat and Summit (upright, dense canopies), and Van (spreading, open canopy). Light transmittance was highest in Van canopies. Therefore, Van allowed an easier penetration of the visible radiation through the canopy, which improves photosynthetic rates, especially at harvest. Conversely, no differences in Ψ_stem were found among cultivars. Van showed the highest leaf mass per unit area and variations in this parameter were mainly associated with alterations in leaf thickness than in leaf density. Leaves of Summit and Van were thicker than those of Burlat, mainly due to increased palisade and spongy parenchyma thickness. However, Burlat leaves had the highest palisade/spongy ratio. Total chlorophyll concentration per area and the chlorophyll a/b ratio were always higher in Van leaves than in the other two cultivars. In contrast, Van leaves had the lowest concentrations of soluble carbohydrates and starch. In dense canopies of Summit and Burlat, light reduction caused a notable increase in the relative concentration of total phenols. The above results provide useful information about the biological behaviour of sweet cherry cultivars with open and dense canopies in order to help the agronomical decisions regarding the local environmental conditions and the consumers’ preference. In particular, it is important to manipulate factors such as orchard exposure, row orientation, plant spacing, training system and pruning, which are able to reduce shading in the canopy.  相似文献   

Efficacy of medical grade honey in the management of canine otitis externa – a pilot study          下载免费PDF全文

Emi Maruhashi  Berta São Braz  Telmo Nunes  Constança Pomba  Adriana Belas  José Henrique Duarte‐Correia  Ana Mafalda Lourenço 《Veterinary dermatology》2016,27(2):93-e27

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