A population of 96 doubled haploid lines (DHLs) was prepared from F1 plants of the hexaploid wheat cross Chinese Spring x SQ1 (a high abscisic acid-expressing breeding line) and was mapped with 567 RFLP, AFLP, SSR, morphological and biochemical markers covering all 21 chromosomes, with a total map length of 3,522 cM. Although the map lengths for each genome were very similar, the D genome had only half the markers of the other two genomes. The map was used to identify quantitative trait loci (QTLs) for yield and yield components from a combination of 24 site x treatment x year combinations, including nutrient stress, drought stress and salt stress treatments. Although yield QTLs were widely distributed around the genome, 17 clusters of yield QTLs from five or more trials were identified: two on group 1 chromosomes, one each on group 2 and group 3, five on group 4, four on group 5, one on group 6 and three on group 7. The strongest yield QTL effects were on chromosomes 7AL and 7BL, due mainly to variation in grain numbers per ear. Three of the yield QTL clusters were largely site-specific, while four clusters were largely associated with one or other of the stress treatments. Three of the yield QTL clusters were coincident with the dwarfing gene Rht-B1 on 4BS and with the vernalisation genes Vrn-A1 on 5AL and Vrn-D1 on 5DL. Yields of each DHL were calculated for trial mean yields of 6 g plant(-1) and 2 g plant(-1) (equivalent to about 8 t ha(-1) and 2.5 t ha(-1), respectively), representing optimum and moderately stressed conditions. Analyses of these yield estimates using interval mapping confirmed the group-7 effects on yield and, at 2 g plant(-1), identified two additional major yield QTLs on chromosomes 1D and 5A. Many of the yield QTL clusters corresponded with QTLs already reported in wheat and, on the basis of comparative genetics, also in rice. The implications of these results for improving wheat yield stability are discussed.

Irrigated olive is rapidly increasing in arid and semiarid areas, many of which may be negatively affected by soil salinity. We evaluated changes in trunk growth and leaf Cl ) , Na + and K + concentrations in young Arbequina olives (Olea europaea L.) grown in a saline-sodic field over a three-year period. The trunk diameter was measured at the beginning and the end of the 1999 (70 trees), 2000 (59 trees) and 2001 (42 trees) growing periods. Leaves, sampled in August of each year, were analyzed for Cl ) , Na + and K + concentrations. Soil salinity (apparent electrical conductivity, ECa) of each monitored tree was measured 14 times during the 1999-2001 experimental period with an electromagnetic sensor and converted to root zone electrical conductivity of the soil saturation extract (ECe) based on ECa-ECe calibration curves. Salinity tolerance was determined using the Maas and Hoffman 'threshold-slope' response model. Based on salinity thresholds (ECe thr ), the tolerance of olive in terms of trunk growth was high in 1999 (ECe thr = 6.7 dS m )1 ), but declined with age and time of exposure to salts by 30% in 2000 (ECe thr = 4.7 dS m )1 ) and by 55% in 2001 (ECe thr = 3.0 dS m )1 ). Based on the high absolute slopes obtained in all years (values between 16% and 23% dS )1 m), olive was classified as very sensitive to ECe values above the threshold. Trunk growth thresholds based on leaf ion concentrations varied, depending on years, between 2.6 and 4.0 mg g )1 (Cl thr ) and between 1.0 and 1.2 mg g )1 (Na thr ), indicating that Arbequina olive was less sensitive to leaf Cl ) and much more sensitive to leaf Na + than values reported as toxic in greenhouse studies. Leaf K + slightly decreased with increasing salinity, whereas the K + /Na + ratio sharply decreased with increasing salinity. We concluded that the initial salinity tolerance of olive was high, but declined sharply with time of exposure to salts and became quite sensitive due primarily to increasing toxic concentrations of Na + in the leaves.

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-One year-old Pinus halepensis seedlings, grown in peat-vermiculite-pine bark mix in 200 cm 3 containers, were moved to a growth chamber and submitted to a progressive decrease of temperature and photoperiod for three months. Morphological parameters and nutrient and non-structural carbohydrate content were measured. Root growth potential, freezing and drought resistance tests were assessed. Although height growth stopped when the minimum temperature fell below 9 ºC, shoot dry weight increased further. Needle potassium concentration and K/N ratio increased progressively and significantly throughout the trial. This may be attributed to potassium accumulation. As height growth stopped, physiological changes were detected in shoot nitrogen and soluble sugar concentrations, root activity and hydraulic conductance maintenance. Nevertheless, cold and drought resistance tests, as well as root regeneration potential, did not reveal any sign of plant stress tolerance until the minimum temperature decreased to 8 ºC and photoperiod to 9 h. This latter temperature may be considered to be the threshold for Pinus halepensis to accumulate the required chilling hours that make seedlings suitable for afforestation purposes. At least, more than 330 chilling hours (£ 8 ºC) are required to reach a minimum level of stress hardiness. The Fv/Fm chlorophyll fluorescence ratio, measured just one day after the freezing test, provides a good estimate of plant frost tolerance.Pinus halepensis / plant quality / stress tolerance / chilling hours / chlorophyll fluorescence / plant nutrition Résumé -Effets de la température sur la croissance et le développement de la résistance au stress de semis de Pin d'Alep (Pinus halepensis Mill.). Des semis de Pin d'Alep (Pinus halepensis), âgés d'un an, croissant sur un mélange de tourbe-vermiculite-écorce de pin dans des containers de 200 cm 3 , ont été mis en place dans une chambre de croissance et soumis, pour une période de 3 mois, à une température et photopériode décroissant progressivement. Des paramètres morphologiques, de nutrition et de teneur carbonée non structurale ont été mesurés. Des tests de potentiel de croissance racinaire, de résistance au froid et à la sécheresse ont été réalisés. Bien que la croissance en hauteur se soit arrêtée lorsque la température minimum eu atteint 9°C, la masse sèche des pousses continue d'augmenter. La concentration en potassium des aiguilles, le rapport K/N augmente progressivement et significativement au cours de l'essai. Ceci peut être attribué à une accumulation de potassium. Lorsque la croissance en hauteur s'est arrêtée, des changements physiologiques ont été constatés pour la concentration en azote et en sucre soluble des pousses, dans l'activité des racines et dans le maintien de la conductance hydraulique. Cependant, les tests de résistance au froid et à la sécheresse, de même que le potentiel de régénération racinaire, ne révélèrent aucun signe de tolérance de la plante au stress jusqu'à ce que la température minimum décroisse à 8°C et la ph...

This study examines the composition of oils extracted from young olive trees of the Arbequina and Empeltre varieties grown with irrigation in the same farm throughout a period of three seasons. Quality parameters, Fatty acid composition, sterols, waxes and aliphatic alcohols were analyzed. Although the quality of oils of both varieties was that of extra virgin, varietal differences were found. The peroxide value and the content of total polyphenols were much higher in Empeltre, whereas stability was higher in Arbequina. The monounsaturated acids were higher in Arbequina containing more stearic, oleic, arachidic and behenic acids than Empeltre, while this variety surpassed Arbequina in palmitic, margaroleic, linoleic, linolenic, gadoleic and lignoceric acids. The sterol composition was also different in the two varieties with higher contents of 24-methylencholesterol, campesterol and, especially, Δ-5 avenasterol in Arbequina, and campestanol, Δ-7 stigmastenol, Δ-7 Avenasterol in Empeltre. The contents of both waxes and aliphatic alcohols were higher in Arbequina.

Este trabajo analiza la composición de aceites de árboles jóvenes de las variedades Arbequina y Empeltre cultivados en regadío en una misma finca. Durante tres campañas se estudiaron los parámetros de calidad, la composición en ácidos grasos, los esteroles, las ceras y los alcoholes alifáticos. Aunque la calidad de los aceites de las dos variedades fue la de virgen extra se encontraron diferencias varietales. El índice de peróxidos y los polifenoles totales tuvieron valores muy superiores en la variedad Empeltre, sin embargo la estabilidad fue mayor en Arbequina. El total de ácidos monoinsaturados fue mayor en Arbequina y el de poliinsaturados en Empeltre. Arbequina contenía más esteárico, oleico, araquídico y behénico que Empeltre, en tanto que en esta variedad era mayor en palmítico, margaroleico, linoleico, linolénico, gadoleico y lignocérico. La composición esterólica fue también diferente en las dos variedades, con mayores contenidos de 24-metilencolesterol, campesterol y, especialmente en Δ-5 Avenasterol en Arbequina, y de campestanol, Δ-7 Estigmastenol, Δ-7 Avenasterol en Empeltre. Tanto el contenido en ceras como el de alcoholes alifáticos fueron mayores en Arbequina