QTL mapping of grain yield and phosphorus efficiency in barley in a Mediterranean-like environment.

KEY MESSAGE: Key QTLs were identified for P efficiency in barley. Phosphorus efficiency and grain yield can be improved simultaneously in breeding. An important breeding goal for many crop species is improved phosphorus (P) efficiency. As in many other crops, selection for P efficient barley varieties has been slow because of inconsistent definitions of P efficiency and unknown genetic controls of P efficiency. We used two criteria to assess P efficiency in a doubled haploid Commander/Fleet population: P responsiveness (estimated as the deviation from the regression of yield with added P against yield with no added P treatment) and PUE (relative yield). Phosphorus responsiveness, PUE and grain yield were phenotyped at 0 and 30 kg P/ha in five environments. Lines consistently responsive to 30 kg P/ha across environments had the highest yield at the two P rates, and P responsiveness showed significantly higher broad sense heritability than PUE in the materials we studied. Genotyping of the population was subjected to a 9,000 single nucleotide polymorphism array and quantitative trait loci (QTLs) for P responsiveness were mapped with yield at 30 kg P/ha, which are common QTLs for yield when P was not limiting growth. The largest QTL for P responsiveness was mapped to 7HL in 2 years. PUE varied from 31 to 124 % across environments and one of the QTLs for PUE was mapped with yield at 0 kg P/ha. Our results demonstrate P responsiveness and grain yield can be improved simultaneously under high-input agricultural systems, but breeding for high PUE varieties may need to explore landrace or wild barley germplasm for low P tolerant alleles.

Fully automated open access platform for rapid, combined serial evaporation and sample reformatting.

This paper reports a novel evaporator and its integration with an automated sample handling system to create a high throughput evaporation platform. The Vaportec V-10 evaporator uses a high speed rotation motor ( approximately 6000 rpm) to spin the vial containing a sample, creating a thin film of solvent which can be readily evaporated by the application of heat to the vial, while the consequent centrifugal force prevents "bumping". An intelligent algorithm controls pressure and temperature for optimum solvent removal conditions and end of run detection, critical for automation. The system allows the option of evaporation directly from a sample source vial, or alternatively, integrated liquid handling facilities provide the capability of transferring samples portionwise from a (large) source vial or bottle to a (small) daughter container, enabling efficient sample reformatting, with minimum user intervention. The open access system makes significant advances over current vacuum centrifugal evaporators in terms of evaporation rate and ease of automation. The evaporator's main features, the integration of robotics to provide automation, and examples of evaporation rates of a wide range of solvents from a variety of containers are described.