ALBERT

Description: We report on the present status of the Lawrence Livermore AMS spectrometer, including sample throughput and progress towards routine 1% measurement capability for 14C, first results on other isotopes and experience with a multisample high-intensity ion source.

Description: 1. An experiment, lasting 3 years, was carried out to investigate the control of hypomagnesaemia on a medium-heavy loam soil in Northern Ireland, using as criteria herbage analysis and analysis of blood sera of grazing dairy cows.2. Applications of calcined magnesite and magnesian limestone as soil treatments raised the magnesium contents of herbage slightly but not to levels judged to be safe. Low blood sorum magnesium levels were recorded for cows grazing this herbage although no cases of tetany occurred.3. Magnesium sulphate, appliedas a spray, temporarily raised the ‘apparent’ magnesium content of the herbage but was easily washed off by rain.4. Finely powdered calcined magnesite applied as a dust to the herbage immediately before grazing appeared to be a promising method of control under Northern Ireland conditions.

Description: SUMMARYA model is derived that relates yield to levels of applied fertilizer in terms of parameters that have direct physical meaning. N8, P8, and K8 define the contribution of the soil to the supply of nitrogen, phosphorus and potassium for plant growth; BN, BP and BK define the responses to nitrogen, phosphorus and potassium fertilizer at low nutrient levels and aN is the level of nitrogen required to raise the osmotic pressure sufficiently to prevent growth.To test the model, field experiments were carried out on French beans and summer cabbage in which 125 different combinations of levels of nitrogen, phosphate and potassium fertilizers were applied. The yield data from each block of each experiment fitted the model very well. Fitted values differed from block to block but these differences could be attributed to the fact that for each block equally good fits were often obtained with widely differing parameter values. Estimates of N8 were made from chemical analysis of the (NH4 + NO3) — N of soil samples from the field plots, and P8, and K8 from chemical studies of the adsorption of phosphate and potassium on untreated soil. They were in substantial agreement with the average values obtained by the entirely different procedure of fitting the model to the yield data. Also estimated values for BN, BP and BK and aN from other chemical studies were consistent with those obtained by model fitting.It is concluded that although the theory has limitations it is broadly in accord with the results of the detailed field experiments.

Description: SUMMARYAlmond trees (Amygdalus communis L. cvs Garrigues and Ramillete) were grown in the field under non-irrigated conditions in Murcia, Spain. Seasonal variations in leaf water potential components were studied in 1989. Predawn leaf water potential showed high values in both cultivars, due to the absence of soil water stress. Pressure-volume curve analysis indicated that the leaf osmotic potential at full saturation (Ψo(sat)) for cv. Garrigues remained fairly constant throughout the season. Bulk modulus of elasticity (E) showed, in both cultivars, a tendency to decrease as the season progressed. E values were higher in Ramillete than in Garrigues. The relative water content at the turgor loss point (RWCtlp) seemed to be controlled by E values. The larger relative apoplastic water content (RWCa found in Ramillete might have allowed it to retain more water at low leaf water potentials than Garrigues. These facts would support the suggestion that Ramillete is a more drought-resistant cultivar than Garrigues.

Description: SUMMARYAlthough direct selection for seed yield under water deficit can result in genetic gains in the common bean (Phaseolus vulgaris L.), progress could be enhanced through selection for additional traits that are related to underlying mechanisms of adaptation to water deficit. Carbon isotope discrimination (Δ) has received considerable attention as an indicator of water use efficiency and adaptation to water deficit. To test the utility of Δ as a selection criterion, Δ and other traits were measured in F2 and F3 generations of a nine-parent diallel grown under rainfed conditions at two locations in Colombia with contrasting soil types. An irrigated trial was also conducted at one location. Significant (P 0·05) differences among parents, F2 and F3 were found for carbon isotope discrimination (Δ), leaf optical density (OD), leaf nitrogen (N) and potassium (K) concentrations, relative duration of pod-filling period (RDPF), shoot dry weight (SDW) and harvest index (HI). Effect of location and water regime and their interactions with genotype were also frequently significant. Heritability estimates, determined by regressing the F3 on the F2, ranged from 0·11±011 (S.E.) to 0·33 ±0·10 for OD, 0·22 ± 0·07 to 0·44±0·09 for N, 0·04±0·05 to 0·29±0·08 for K, 0·40 ± 0·08 to 0·43 ± 0·15 for RDPF and 0·30±0·22 to 1·00±0·24 for SDW. All values for Δ and HI did not differ significantly from zero. Correlations between seed yield and OD and RDPF were negative, whereas those with N, K, SDW, and HI were positive. For all traits, mean square values for general combining ability (GCA) were usuall significant and larger than those for specific combining ability (SCA). All significant GCA effects for Δ for ‘Rio Tibagi’, ‘San Cristobal 83’ and ‘Apetito’ were negative, while those for ‘Bayo Rio Grande’, ‘Bayo Criollo del Llano’, ‘Durango 222’ and BAT1224 were positive. Although Δappears unsuitable as an indirect criterion for selection for yield under water deficit, further study of genotypes exhibiting contrasting values of A might reveal differences in mechanisms of adaptation to water deficits, thus leading to other selection criteria or identification of valuable parental lines.

Description: SummaryRed blood cell electrolyte levels and haemoglobin types have been determined in flocks of Peppin Merino sheep genetically different for clean fleece weight and crimp frequency. The flocks selected for high clean fleece weight or low crimp frequency had significantly higher mean erythrocyte potassium levels than did those flocks selected for low clean fleece weight or high crimp frequency, this difference was apparent in both haemoglobin AB and BB types. Erythrocyte potassium concentration was not correlated with either clean fleece weight or crimp frequency within flocks. The high clean fleece weight flock had a significantly higher gene frequency for high potassium than did the low clean fleece weight flock, while the high crimp frequency flock had a lower haemoglobin B gene frequency than the low crimp frequency flock.

Description: SummaryA model was developed to assess the suitability of land in England and Wales for growing newly developed genotypes of autumn-sown determinate white lupins. The model used soil pH, the number of degree-days accumulated for mainstem leaf production before the apical meristem of the mainstem became floral, and the number of machinery work days in autumn. Interactions between these three components were used to set thresholds to determine land suitability within 5 × 5 km grid squares of the National Soil Map.Of the potential 13·75 Mha of arable land in England and Wales, a total of 7·54 Mha are well or moderately suited to growing these lupin genotypes. This is equivalent to c. 2 Mha of land within the arable rotation each year. It was estimated that, because of low soil pH, lupins would be the preferred legume on 0·3 Mha out of this 2 Mha. The model was also used to assess the risk of soil acidification and nitrate leaching following mineralization of lupin residues. This exercise indicated that there was little risk of either on much of the land suited to lupins.

Description: SUMMARYIn experiments at Rothamsted in 1984–86, seven factors, each at two levels, were tested in factorial combination on winter barley (cv. Panda) grown as a third take-all susceptible crop. The factors were seed rate, a growth regulator prior to stem extension, amounts of N in spring, ‘winter’ nitrogen, an autumn insecticide, a fungicide applied to the seed (‘Baytan’) and a programme of fungicide sprays in spring and summer. Sowing 50% more seeds than normal increased the number of ears/unit area but had no effect on mean grain yield because grains were smaller. There were, however, significant, but unexplained, interactions between seed rate and the fungicide ‘Baytan’ applied to the seed. A growth regulator applied prior to stem extension had little effect on crop growth and no significant effect on grain yield. If sufficient N was applied in April there was little benefit from applying ‘winter’ N (30 kg/ha in November and again in February/March) except in 1985 when the amount of NO3-N in the soil, measured in the previous October, was lowest. Insecticide sprays applied in autumn to control the aphid vectors of barley yellow dwarf virus (BYDV) had no significant effect on grain yield but infectivity indices were below the threshold needed for treatment in each year. On average, ‘Baytan’ applied to the seed increased grain yield by 0·28 t/ha and this was associated with decreases in the severity of take-all. Over the three years, programmes of fungicide sprays, applied during spring and summer, increased grain yield by 0·92 t/ha but the mean response was largest where most N was applied.The experiments also allowed the importance of interactions between different agronomic factors to be examined. A combined analysis of grain yields for all three years (based on 192 plot values) showed that only six 2- or 3-factor interactions, out of the 73 estimated, were significant (P 〈 0·05). Two of these interactions reflected variable responses to ‘winter’ N and fungicide sprays in the three years and three of the remaining four involved ‘Baytan’.Additional plots of barley grown after oats had little take-all and yielded 1·14 t/ha more grain than similarly treated plots grown after barley. These responses were obtained despite evidence that oat residues had adverse effects on the growth of barley seedlings. Additional plots of barley grown after a bare fallow also had little take-all and gave even larger total yields (grain plus straw) than did barley after oats but the mean yield of grain was less than after oats because more of the dry matter after a fallow was straw. In 1984, when take-all was relatively slight, plots after a fallow gave even less grain than plots after barley (−0·77 t/ha) despite producing 2·12 t/ha more dry matter in grain plus straw.

Description: SummaryThe Comores Archipelago comprises four principal islands, lying in a WNW–ESE line at the northern end of the Mozambique Channel. The Islands are almost entirely volcanic and show a simple age progression from Grande Comore, with its active shield volcano Kharthala (2650m), east-south-eastwards through Mohéli and Anjouan, which are quite deeply dissected, to Mayotte, which is in an advanced stage of erosion and subsidence, and is encircled by a barrier reef. There is also evidence of minor volcanic rejuvenation in relatively recent times in Mayotte, and perhaps Anjouan and Mohéli. The lavas of Kharthala, and the neighbouring extinct shield volcano (Massif de la Grille) on Grande Comore are all basaltic, ranging from oceanitic and ankaramitic to aphyric types. Numerous tuff cones occur, especially on the flanks of Massif de la Grille. Basaltic lavas, similar to those of Grande Comore, form the bulk of the dissected volcanic shields of Mohéli and Anjouan, but there is also evidence of differentiation towards alkalic under-saturated end products, both as lavas and as intrusive bodies. Lherzolitic and gabbroic nodules are locally abundant on each of the islands, while xenoliths of sandstone and quartzite have been found on the three westernmost islands. Petrochemical data are presented for a considerable variety of Comores rocks, and the volcanic activity is discussed in terms of the major structural features of the Madagascar-Mozambique region.

Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Reimer, P. J., Austin, W. E. N., Bard, E., Bayliss, A., Blackwell, P. G., Ramsey, C. B., Butzin, M., Cheng, H., Edwards, R. L., Friedrich, M., Grootes, P. M., Guilderson, T. P., Hajdas, I., Heaton, T. J., Hogg, A. G., Hughen, K. A., Kromer, B., Manning, S. W., Muscheler, R., Palmer, J. G., Pearson, C., van der Plicht, J., Reimer, R. W., Richards, D. A., Scott, E. M., Southon, J. R., Turney, C. S. M., Wacker, L., Adolphi, F., Buentgen, U., Capano, M., Fahrni, S. M., Fogtmann-Schulz, A., Friedrich, R., Koehler, P., Kudsk, S., Miyake, F., Olsen, J., Reinig, F., Sakamoto, M., Sookdeo, A., & Talamo, S. The Intcal20 Northern Hemisphere radiocarbon age calibration curve (0-55 cal kBP). Radiocarbon, 62(4), (2020): 725-757, doi:10.1017/RDC.2020.41.

Description: Radiocarbon (14C) ages cannot provide absolutely dated chronologies for archaeological or paleoenvironmental studies directly but must be converted to calendar age equivalents using a calibration curve compensating for fluctuations in atmospheric 14C concentration. Although calibration curves are constructed from independently dated archives, they invariably require revision as new data become available and our understanding of the Earth system improves. In this volume the international 14C calibration curves for both the Northern and Southern Hemispheres, as well as for the ocean surface layer, have been updated to include a wealth of new data and extended to 55,000 cal BP. Based on tree rings, IntCal20 now extends as a fully atmospheric record to ca. 13,900 cal BP. For the older part of the timescale, IntCal20 comprises statistically integrated evidence from floating tree-ring chronologies, lacustrine and marine sediments, speleothems, and corals. We utilized improved evaluation of the timescales and location variable 14C offsets from the atmosphere (reservoir age, dead carbon fraction) for each dataset. New statistical methods have refined the structure of the calibration curves while maintaining a robust treatment of uncertainties in the 14C ages, the calendar ages and other corrections. The inclusion of modeled marine reservoir ages derived from a three-dimensional ocean circulation model has allowed us to apply more appropriate reservoir corrections to the marine 14C data rather than the previous use of constant regional offsets from the atmosphere. Here we provide an overview of the new and revised datasets and the associated methods used for the construction of the IntCal20 curve and explore potential regional offsets for tree-ring data. We discuss the main differences with respect to the previous calibration curve, IntCal13, and some of the implications for archaeology and geosciences ranging from the recent past to the time of the extinction of the Neanderthals.

Description: We would like to thank the National Natural Science Foundation of China grants NSFC 41888101 and NSFC 41731174, the 111 program of China (D19002), U.S. NSF Grant 1702816, and the Malcolm H. Wiener Foundation for support for research that contributed to the IntCal20 curve. The work on the Swiss and German YD trees was funded by the German Science foundation and the Swiss National Foundation (grant number: 200021L_157187). The operation in Aix-en-Provence is funded by the EQUIPEX ASTER-CEREGE, the Collège de France and the ANR project CARBOTRYDH (to EB). The work on the correlation of tree ring 14C with ice core 10Be was partially supported by the Swedish Research Council and the Knut and Alice Wallenberg foundation. M. Butzin was supported by the German Federal Ministry of Education and Research (BMBF) as Research for Sustainable Development (FONA; http://www.fona.de) through the PalMod project (grant number: 01LP1505B). S. Talamo and M. Friedrich are funded by the European Research Council under the European Union’s Horizon 2020 Research and Innovation Programme (grant agreement No. 803147-RESOLUTION, awarded to ST). CA. Turney would like to acknowledge support of the Australian Research Council (FL100100195 and DP170104665). P. Reimer and W. Austin acknowledge the support of the UKRI Natural Environment Research Council (Grant NE/M004619/1). T.J. Heaton is supported by a Leverhulme Trust Fellowship RF-2019-140\9. Other datasets and the IntCal20 database were created without external support through internal funding by the respective laboratories. We also would like to thank various institutions that provided funding or facilities for meetings.