[1] Most magmatic systems on Earth are located at actively deforming plate boundaries. In these systems, the magmatic and plate boundary deformation signals are intertwined and must be deconvolved to properly estimate magma flux and source characteristics of the magma plumbing system. We investigate the inter-rifting and inter-seismic deformation signals at the Eastern Volcanic Zone (EVZ) -South Iceland Seismic Zone (SISZ) ridge -transform intersection and estimate the location, depth, and volume rate for magmatic sources at Hekla and Torfajökull volcanoes, which are located at the intersection. We solve simultaneously for the source parameters of the tectonic and volcanic deformation signals using a new ten-year velocity field derived from a dense network of episodic and continuous GPS stations in south Iceland. We find the intersection of the axes of the EVZ and the SISZ is located within the Torfajökull caldera, which itself is subsiding. Deformation at Hekla is statistically best described in terms of a horizontal ellipsoidal magma chamber at 24 À2 +4 km depth aligned with the volcanic system and increasing in volume by 0. +0.003 km 3 per year are also plausible models explaining the deformation at Hekla. All three models indicate magma accumulation in the lower crust or near the Moho under Hekla.

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InterspeciWc hybrids were produced from reciprocal crosses between Brassica napus (2n = 38, AACC) and B. oleracea var. alboglabra (2n = 18, CC) to introgress the zero-erucic acid alleles from B. napus into B. oleracea. The ovule culture embryo rescue technique was applied for production of F 1 plants. The eVects of silique age, as measured by days after pollination (DAP), and growth condition (temperature) on the eYciency of this technique was investigated. The greatest numbers of hybrids per pollination were produced under 20°/15°C (day/night) at 16 DAP for B. oleracea ($) £ B. napus crosses, while under 15°/10°C at 14 DAP for B. napus ($) £ B. oleracea crosses. Application of the ovule culture technique also increased the eYciency of BC 1 (F 1 £ B. oleracea) hybrid production by 10-fold over in vivo seed set. The segregation of erucic acid alleles in the selfpollinated backcross generation, i.e. in BC 1 S 1 seeds, revealed that the gametes of the F 1 and BC 1 plants carrying a greater number of A-genome chromosomes were more viable. This resulted in a signiWcantly greater number of intermediate and a smaller number of high-erucic acid BC 1 S 1 seeds.

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