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Root niche differentiation for optimal exploitation of resources was found in an arabica coffee agroforestry system in Nicaragua. Rooting behavior was compared in both unshaded (FS) and shaded (AFS) coffee combined with two previously untested tropical timber species (deciduous Tabebuia rosea Bertol. and evergreen Simarouba glauca DC.). The predominant andisol possesses a compacted soil layer (talpetate). The study was conducted in sub-optimal environmental conditions for coffee cultivation (455 m.a.s.l., annual mean 27 °C, 1300 mm rainfall/year, 6 months dry season) in Nicaragua. Twelve and five trenches 200 cm deep were dug in AFS and FS respectively. Roots per unit area were counted on two perpendicular soil faces. Volumetric water was measured continuously over 2 years by using 45 reflectometers in different soil layers. The talpetate varied greatly in depth, thickness and physical structure. Coffee fine roots were more abundant than tree roots and were concentrated in the shallower strata (0-80 cm) whilst tree roots proliferated more below 100 cm. The S. glauca root system was denser below 100 cm than T. rosea root system. There was no meaningful difference in coffee root counts in FS and under T. rosea, but coffee root counts were higher near S. glauca trees. 2012 and 2014 had mild dry seasons and whole profile soil water content was similar in FS and AFS, but in the 2013 severe dry period volumetric water and water uptake were lower in AFS than in FS. This indicates that the normal advantage of greater soil exploration in AFS was cancelled presumably due to continued water uptake by deep rooting trees whereas the FS still had available water. [ABSTRACT FROM AUTHOR]

Two bread wheat lines each with a translocation on chromosome 7DL from either Thinopyrum intermedium (TC5 and TC14) or Thinopyrum ponticum (T4m), were hybridized in a ph1b mutant background to enhance recombination between the two translocated chromosomal segments. The frequency of recombinants was high in lines derived from the larger and similar-sized translocations (TC5/T4m), but much lower when derived from different-sized translocations (TC14/T4m). Recombinant translocations contained combinations of resistance genes Bdv2, Lr19 and Sr25 conferring resistance to Barley yellow dwarf virus (BYDV), leaf rust and stem rust, respectively. Their genetic composition was identified using bioassays and molecular markers specific for the two progenitor Thinopyrum species. This set of 7DL Th. ponticum/ intermedium recombinant translocations was termed the Pontin series. In addition to Thinopyrum markers, the size of the translocation was estimated with the aid of wheat markers mapped on each of the 7DL deletion bins. Bioassays for BYDV, leaf rust and stem rust were performed under greenhouse and field conditions. Once separated from ph1b background, the Pontin recombinant translocations were stable and showed normal inheritance in successive backcrosses. The reported Pontin translocations integrate important resistance genes in a single linkage block which will allow simultaneous selection of disease resistance. Combinations of Bdv2 + Lr19 or Lr19 + Sr25 in both long and short translocations, are available to date. The smaller Pontins, comprising only 20 % of the distal portion of 7DL, will be most attractive to breeders. [ABSTRACT FROM AUTHOR]

Rusts and barley yellow dwarf virus (BYDV) are among the main diseases affecting wheat production world wide for which wild relatives have been the source of a number of translocations carrying resistance genes. Nevertheless, along with desirable traits, alien translocations often carry deleterious genes. We have generated recombinants in a bread wheat background between two alien translocations: TC5, ex- Thinopyrum ( Th) intermedium, carrying BYDV resistance gene Bdv2; and T4m, ex- Th. ponticum, carrying rust resistance genes Lr19 and Sr25. Because both these translocations are on the wheat chromosome arm 7DL, homoeologous recombination was attempted in the double hemizygote (TC5/T4m) in a background homozygous for the ph1b mutation. The identification of recombinants was facilitated by the use of newly developed molecular markers for each of the alien genomes represented in the two translocations and by studying derived F2, F3 and doubled haploid populations. The occurrence of recombination was confirmed with molecular markers and bioassays on families of testcrosses between putative recombinants and bread wheat, and in F2 populations derived from the testcrosses. As a consequence it has been possible to derive a genetic map of markers and resistance genes on these previously fixed alien linkage blocks. We have obtained fertile progeny carrying new tri-genomic recombinant chromosomes. Furthermore we have demonstrated that some of the recombinants carried resistance genes Lr19 and Bdv2 yet lacked the self-elimination trait associated with shortened T4 segments. We have also shown that the recombinant translocations are fixed and stable once removed from the influence of the ph1b. The molecular markers developed in this study will facilitate selection of individuals carrying recombinant Th. intermedium– Th. ponticum translocations (Pontin series) in breeding programs. [ABSTRACT FROM AUTHOR]

The ilmenite-hematite (1 - x) FeTiO3 · xFe2O3 solid solution system is considered to be a novel material for spin-electronics, microelectronics, high-temperature electronics, and radhard electronics. This paper focuses on thin films of composition x = 0.33 grown on (100) MgO single-crystal substrates using pulsed-laser deposition (PLD) under different argon-oxygen mixtures. The surface of the MgO was found to possess MgO2 crystals, yielding an orientation relationship, [001] MgO || [011] MgO2 and (100)MgO || (1̄10) MgO2. The structural characterizations show that the films are crystalline and homogeneous without any secondary phase. The films show a weak and inclined (112̄0) growth epitaxy. A bandgap of 3.4-3.7 eV was obtained for these films from optical measurements carried out in the UV-visible region. Electrical measurements confirmed the semiconducting behavior. However, the resistivity was found to increase substantially on the slightest addition of oxygen into the chamber. [ABSTRACT FROM AUTHOR]