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Yield crops is a complex component depending on several grain filling traits. Knowledge of their relative contribution to grain yield determination under contrasting environments is essential to optimize grain yield and its stability. This study evaluates the changes resulting from durum wheat breeding in Morocco during the last three decades on grain filling rate (R) and duration (D), final grain weight (W), and days from sowing to anthesis (DSA). A set of six durum wheat varieties, released between 1984 and 2007, was grown in experiments conducted under contrasting environments during three growing seasons. The analysis of variance revealed that water regimes and growing seasons accounted for the largest percentages of variability for R, D, W, and DSA. D and DSA increased significantly over time under both water regimes. W exhibited an increasing trend under irrigated conditions, but a significant decline under rainfed ones. In contrast, the change of R was only significant under irrigated conditions. The path coefficient revealed that irrigated and rainfed conditions impacted differently the direct and indirect effects among traits with higher values of direct effects recorded under water-limited conditions. Within irrigated trials, R and D affected directly and positively grain yield. Regarding rainfed conditions, grain yield was only dependent on W. These findings indicate that genetic progress in grain filling traits and their direct and indirect effects on grain yield differed significantly between rainfed and irrigated conditions. Therefore, when selecting for high-yielding durum wheat genotypes, a particular attention should be paid to the environmental conditions.

Drought is one of the main environmental factors affecting grain yield and plant architecture in durum wheat. The present work was conducted to evaluate the contribution of morphological traits above flag leaf node on grain yield of six Moroccan durum wheat varieties released between 1984 and 2007 and grown under two water regimes (irrigated and rainfed) during the 2015–2016 crop season. The following morphological traits were measured at anthesis: Flag leaf length (FLL), flag leaf area (FLA), peduncle length (PL), spike length (SL), spike area (SA), and green leaf area (GLA). Days from sowing to anthesis (DSA) and grain-filling period (GFP) were recorded. In addition, grain yield per plant (GYP) was evaluated at maturity. Analysis of variance showed the greater effect of water stress in explaining total variability of the studied traits. Mean comparisons indicated that water deficit significantly affected GYP and all morphological traits; it shortened DSA and GFP by 4 and 7 days, respectively. Moreover, GYP, DSA, and GFP increased in modern varieties. In contrast, FLL, FLA, and PL were reduced from old to modern varieties. Under irrigated conditions, correlation studies revealed that GYP was positively associated to GLA. Regarding the rainfed trial, GYP was positively correlated to FLL. Additionally, negative relationships were found between GYP and DSA in both water regimes. Stepwise regression highlighted the relative importance of each morphological traits on the stress susceptibility index, FLL was the most consistent trait entered the model followed by PL and FLA. In this study, some morphological traits above flag leaf node proved to be useful tools to select for grain yield in water-limited environments.

Cultivated almond is an important nut crop commercially grown worldwide. The majority of research works carried out on almond fruit has been focused on chemical composition. However, fruit quality is defined by both chemical and physical characteristics, which are still not well documented. Here, we investigated gravimetrical traits of almond fruit in the five following cultivars: ‘Ferraduel’, ‘Ferragnes’, ‘Fournat de Brezenaud’, ‘Marcona’, and ‘Tuono’. The present study was carried out across three different sites in northern Morocco namely Aknoul, Bni Hadifa and Tahar Souk and over two harvest seasons (2015 and 2016). Gravimetrical measurements consisted in: In-hull weight, nut weight, kernel weight, hull percentage, shelling percentage, true density, bulk density, and porosity. The outcomes of ANOVA demonstrated that cultivar, site, harvest season, and their interactions affected significantly almost gravimetrical traits. In fact, hull percentage, kernel bulk density, and both nut true and bulk densities were mainly under genotypic dependency, while harvest season (climatic factor) was the main variability source in kernel weight. Furthermore, site (edaphic factor) was the most important in determining in-hull weight, nut weight, and kernel true density, while shelling percentage, and kernel and nut porosities were controlled jointly by genetic and edaphic factors. Wide variabilities were found between cultivars, sites, and harvest seasons for almost parameters as demonstrated by LSD’s test. Almond kernels from our cultivars were very small (cv. ‘Tuono’), small (cvs. ‘Ferraduel’, ‘Ferragnes’, and ‘Marcona’), and medium (cv. ‘Fournat de Brezenaud’). Furthermore, corresponding nuts were hard (cvs. ‘Fournat d Brezenaud’ and ‘Tuono’) to very hard shelled (cvs. ‘Ferraduel’, ‘Ferragnes’, and ‘Marcona’). Among sites, fruits harvested from Bni Hadifa performed better in terms of in-hull weight, nut weight, and kernel weight. Whereas, Tahar Souk had the greatest values of hull percentage and shelling percentage. Principal component analysis (PCA) allowed a good discrimination of cultivars, sites, and harvest seasons. The first component was of genetic order along which cultivars were separated, while the second and the third components exerted together an environmental control since they separated sites and harvest seasons, respectively. Significant correlations were highlighted among studied characteristics. The most important ones were modeled through simple regressions and therefore they can be used to predict each other.

Almond is the most important tree nut grown commercially worldwide. It is cultivated for its edible kernel of high nutritional and economic values. From an agronomic standpoint and thanks to international breeding programs, several commercial cultivars were released mainly for better kernel quality, self-compatibility, and delayed blooming time to avoid frost risks. Almond phenology also attracted the interest of many researchers but no detailed and specific scale was conceived. To standardize phenological observations among scientists and growers on one hand and accurately schedule timing of agronomic managements on the other hand, a precise phenological scale is needed. To date, BBCH (Biologische Bundesanstalt, Bundessortenamt Chemische Industrie) phenological scale is the most accurate and the widely accepted. In this research work, we characterized almond phenological growth stages using the BBCH scale. Eight of the ten principal developmental stages (0 − 9) from BBCH scale were codified and described. The almond principal growth stages were categorized into reproductive and vegetative phenology. Vegetative phenology included: bud development (stage 0), leaf development (stage 1), shoot development (stage 3), and senescence and beginning of the rest period (stage 9). The reproductive phenology encompassed the four following stages: inflorescence emergence (stage 5), flowering (stage 6), fruit development (stage 7), and fruit maturity (stage 8). To better define these phenological growth stages, illustrative pictures were provided along with codification and description. In addition, we used phenological records over three growing seasons from the main production regions of northern Morocco to draw a schematic representation of the chronological progression of principal growth stages in five widely grown almond cultivars: ‘Ferraduel’, ‘Ferragnes’, ‘Fournat de Brezenaud’, ‘Marcona’, and ‘Tuono’. Some agronomical managements intended to be applicable in an almond orchard were discussed.

Paper description: Olive-growing activity has a great socio-economic importance in Morocco. The negative impact of climatic fluctuations affect young olive plants at a critical growth stage such as flowering. The research was conducted to study the physiological and biochemical responses to water stress in three Moroccan olive varieties at the flowering stage. Our results provide a better estimate of the water requirements of young olive trees. They should find use in good orchard management and improve olive production. Abstract: This study examines physiological and biochemical changes in three Moroccan varieties of young olive trees ( Olea europaea L.) grown under three different water regimes (control, moderate stress and severe stress). Leaf relative water content (RWC), water potential (y w ), transpiration rate (E), stomatal conductance (gs), maximum quantum efficiency of PSII (Fv/Fm), the contents of total chlorophyll (TCC), proline (ProC) and soluble sugars (SSC) were measured at the flowering stage during three growing seasons (2015, 2016 and 2017). ANOVA analyses showed that the effect of the water regime was predominant in all of the examined parameters, except for Fv/Fm, which was under the effect of both water regime and growing season. Impacts of variety and interactions were of lesser magnitude. Water deficit reduced E, y w and gs by 25%, while its effect on RWC and Fv/Fm was a decrease of about 7%; however, increases in SSC and ProC were more than 10%. Among the growing seasons, 2015 flowering displayed the lowest values for RWC, y w , E, gs, TCC and Fv/Fm, and the highest for ProC and SSC. Among plant varieties, no significant differences were observed. The three principal component (PC) axes accounted for 91% of total variance. PC1 was better explained by the water regime, while the growing season fitted PC3 variability. Correlation studies highlighted significant associations between most parameters. Positive relationships were found between RWC, y w , E, gs, Fv/Fm and TCC, while all of these parameters were negatively linked to ProC and SSC. https://doi.org/10.2298/ABS181001054E Received: October 1, 2018; Revised: November 23, 2018; Accepted: November 23, 2018; Published online: December 4, 2018; Published online: Decdember 4, 2018 How to cite this article: El Yamani M, Sakar EH, Boussakouran A, Rharrabti Y. Physiological and biochemical responses of young olive trees ( Olea europaea L.) to water stress during flowering. Arch Biol Sci. 2019;71(1):123-32.

We investigated geometrical traits of almond nuts and its kernels in five major commercial almond cultivars: ’Ferraduel’, ’Ferragnes’, ’Fournat de Brezenaud’, ’Marcona’, and ’Tuono’ at initial moisture content. Three different environments of northern Morocco, namely Aknoul, Bni Hadifa, and Tahar Souk, were considered for sampling. Geometrical determinations were performed both in nuts and kernels, and consisted of the nine following parameters: length (L), width (W), thickness (T), arithmetic mean diameter (Da), geometric mean diameter (Dg), sphericity (Φ), volume (V), surface area (Sa) and projected area (Pa). ANOVA analyses showed that site, cultivar, and their interaction affected significantly all the parameters studied. L and Φ were genetically controlled, while T was environment-dependent for both nuts and kernels as well as Dg, V, Sa, Pa only for nuts. The rest of traits were equally determined by genotypic and environmental effects. Principal component analysis (PCA) explained about 97% and 89% of total variability in almond nuts and kernels, respectively and allowed a good discrimination among sites and cultivars. Among sites, Bni Hadifa favored a better expression of almost investigated traits while for cultivars; ’Marcona`’ exhibited the highest scores for the majority of studied traits. Multiple regression models were developed for Da, Dg, Φ, V, Sa, Pa as function of the three axial dimensions (L, W, T). For almond nuts, Dg, V, and Sa depended mainly on W. Moreover, Φ determined equally by L and T, while Da and Pa were mostly dependent on L. As regards of almond kernels, L was the most consistent trait that determined variation in Da, Dg, Φ, V, Sa, and Pa.

Almond [Prunus dulcis (Mill.) D.A. Webb] is one of the most important nut crops worldwide. It requires chilling during winter to break dormancy and develop fruiting buds. However, late winter chilling and early spring frosts may damage the reproductive tissues leading to productivity reduction. In the present work, we evaluated the frost susceptibility by means of chlorophyll fluorescence in flower buds of almonds cultivated in two different sites in Morocco: Aknoul in the north and Sidi Bouhria in the east. Five widely grown almond cultivars, namely Marcona, Fournat de Brezenaud, Ferragnes, Ferraduel, and Tuono, were involved in this study. Flower buds were incubated in temperatures of –3, –2, –1, 0, and 25 °C during 24 h and thereafter the Fv/Fm ratio was measured at the ovary zone. Combined analysis of variance showed that cultivar was the major source of variability, while site and cultivar by site interaction effects were of lesser extent and explained together less than 20%. At 25 °C, all cu...

The activity of natural additives against the deterioration of virgin olive oil (VOO) in relation to storage time and conditions was examined. Thus, carotenoids and phenols previously extracted from carrot and olive mill wastewater, respectively, were added at 200 and 400 ppm to VOO and stored in clear and amber glass bottles at room temperatures during 120 days. The results showed that enriched VOO was largely influenced by the storage time, which resulted in a significant accumulation of hydrolysis and oxidation products. Storage conditions also affected considerably the enriched VOO. Dark glass bottles offered better protection against oxidative deterioration. The impact of both extracts on the oxidation status of examined VOO was significant and concentration-dependent. The natural additives markedly delayed the formation of hydroperoxides and conjugated dienes and trienes. Results from principal component analysis (PCA) showed that most of the variation was captured by the PC1 (89% of the total variance) which grouped samples in four categories according to storage times, each being divided into two clusters linked to storage conditions. Findings from this study revealed that natural additives could minimize VOO deterioration caused by storage time and conditions (light).

The purpose of this work is to evidence the effects of ripening index and water regime on the quantity and quality indices of “Moroccan Picholine” virgin olive oil (VOO) produced in northern Morocco. Olive trees were subjected to full irrigation and rainfed conditions, and olive fruits were collected at different ripening times. Results showed that the extracted volume of VOO increased during ripening, and decreased when full irrigation was applied. In regard to VOO quality, the statistical analysis revealed the predominant effect of ripening index on the majority of the considered parameters, except total phenols content that was strongly influenced by water regime. At more advanced stages of maturity, lower values of peroxide value, K232, carotenoids, chlorophylls and total phenols were registered while more free fatty acids were accumulated. Moreover, full irrigation reduced total phenols and increased free fatty acids, even if a great amount of pigment content was scored. Correlation studies showed significant relationships between pigments content and oxidation indices (peroxide value and K232).

This work examined the influence of crop season, extraction system and production site on the composition of fresh olive mill wastewater collected from northern Morocco. ANOVA analysis showed that most of the traits were largely affected by the extraction system (≥60% of total variance). Comparison among extraction systems showed significant differences for all traits, except for chlorides. Three phase centrifugation system (C3) displayed the highest value of total phenols, while all the remaining traits were higher in two phase centrifugation system (C2). Concerning crop seasons, we noticed a general decrease in values of total solids, chemical oxygen demand, chlorides, C/N ratio and total aerobic mesophilic flora, from 2014 to 2016 season; in contrast, an increase in suspended solids, total kjeldahl nitrogen and proteins was detected. OMW with highest total phenols content and then more acidic were collected during 2015 season. Between production sites, Bni Frassen produced OMW with the highest values for salt and total phenols, but the lowest ones were obtained for microbiological traits. OMW from Taza were rich in total kjeldahl nitrogen and proteins. An increase in organic load indicators was observed in Bouchfaa. Principal component analysis (PCA) explained about 82% of total variability: 58%, 16% and 8% for principal component 1 (PC1), PC2 and PC3, respectively. Extraction system fitted the variability of PC1. PC2 was mainly explained by production sites, while PC3 separated crop seasons. Correlation studies showed significant relationships especially among the traits expressing organic load, while microbiological counts were largely associated to total phenols and pH.

To produce nut virgin oils at a large scale, mechanical extractions have become widely accepted to obtain nut oils of higher quality without chemical residues. Little is known about kernel oil from the commercially grown almond cultivars in Morocco obtained by press extraction. This work was set up to evaluate effects of different environments on almond oil content (OC) and related quality traits, namely polyphenols (PP), saturated (SFA), monounsaturated (MUFA), polyunsaturated fatty acids (PUFA), and oleic/linoleic (O/L) ratio. To this end, the main cultivars were compared across various sites belonging to northern (typical Mediterranean climate) and the eastern Morocco (hot Mediterranean climate) over three growing seasons (2016–2018). Virgin oil achieved via mechanical press showed high quality as demonstrated by lower records of routinely measured parameters (acid value, peroxide value, and UV absorption coefficients K232 and K270) on one hand and higher records of PP and O/L on the other hand. Cultivars of longer fruit development period (FDP) such as ‘Marcona’ displayed higher OC, while ‘Tuono’ and ‘Fournat de Brezenaud’ (shorter FDP) presented the best record of PP. 2016 (the driest season) had the best scores of OC and PP. Eastern Morocco (relatively hot and dry) showed higher OC, PP, PUFA, but lower MUFA and, therefore, lower O/L. In conclusion, drier environments could enhance OC and foster the accumulation of more PP, PUFA but lower MUFA with a decreased oil stability.

Changes in leaf relative water content (RWC), water potential (Ψw), transpiration rate (E & Tsp), stomatal conductance (gs), maximum quantum efficiency of PSII (Fv/Fm), total chlorophylls, carotenoids, proline and soluble sugars were investigated in young Moroccan olive varieties (‘Moroccan Picholine’, ‘Menara’ and ‘Haouzia’) grown in pots under three water regimes (well-watering, moderate stress and high stress). The water treatment was applied at different growth stages during three growing seasons (2015, 2016 and 2017). Results from ANOVA analyses showed that all parameters were found to be mainly under the impact of the water regime and growth stage. In fact, the severe stress led to significant reductions in Ψw, gs, E and Tsp by more than 24%, but also in RWC, Fv/Fm and total chlorophylls with percentages lower than 15%. In contrast, water shortage activated the accumulation of proline and soluble sugars by about 13%. Among growth stages, the bud development displayed the highest levels for RWC, Ψw, gs, E, Tsp and Fv/Fm, and the lowest ones for proline and soluble sugars, whilst, the opposite was observed during the fruiting stage. Although the impacts of variety, growing season and interactions were of minor extents, we observed some significant differences. In fact, the young olive trees belonging to 'Moroccan Picholine' have shown more resistance to water stress, especially during the 2017 season. Principal component analysis (PCA) showed that 92% of the total observed variability was explained by the first two principal components, and allowed a good discrimination among the tree water regimes and the five growth stages. In addition, positive relationship was established between proline and soluble sugars, which were found negatively associated with the remaining parameters.

The present work analysed whether grain weight is affected by changes in source:sink ratio in twenty-four durum wheat cultivars from Italy and Spain released through the 20th century grown under Mediterranean conditions. For this purpose, a field experiment was conducted during the 2002 growing-season in southeastern Spain. Sink strength was modified by removing half of the spikelets, of one side of the spike, one week after anthesis. Spikelet trimming had different effects on both average grain weight and individual grain weight at different positions within the spike. While old cultivars did not respond positively to spikelet trimming, and appear to be mainly sink-limited, intermediate and modern cultivars from Spain increased their grain weight in response to sink reductions, suggesting co-limitation by the sink and source. On the contrary, grain weight of intermediate and modern Italian cultivars remained relatively unchanged suggesting a sink-limitation to grain yield. The differential response to source-sink manipulations observed between Italian and Spanish cultivars could be attributed to their different genetic background, which determines their level of adaptation to harsh Mediterranean environments. Fil: Rharrabti, Y.. Universidad de Granada; España Fil: Miralles, Daniel Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina Fil: Martos, V.. Universidad de Granada; España Fil: García Del Moral, L.F.. Universidad de Granada; España

Under terminal drought conditions, cereal varieties with limited tillering have been suggested to be advantageous, because they have fewer nonproductive tillers, thereby limiting water consumption prior to anthesis. In this study, four field trials were conducted over two growing seasons in southern Spain, under rainfed and irrigated conditions. Twenty-five genotypes were studied to evaluate the contribution of the main stem (MS) and tillers to grain yield and its components. Significant differences were found among genotypes for these contributions under non-stressed environments, but these differences were not significant under water-stress conditions. The contribution of the MS to plant grain yield was higher than that of tillers (68% vs. 32%) and was stable between years in irrigated trials. However, in the rainfed trials, MS contributed differently depending on year-to-year climate variations. Thus, under favorable weather conditions the contribution of MS to grain yield was higher than in the unfavorable year (85% vs. 59%). In irrigated environments, MS and tiller grain yield depended on the number of grains per spike, spikelets per spike, and thousand kernel weight (TKW). Under water-limited conditions, MS yield depended on the number of grains per spike and grains per spikelet, whereas the number of spikelets and TKW had less influence on MS grain yield. Furthermore, under water-stress conditions, high tillering genotypes showed yield levels similar to the genotypes with restricted tillering. Additionally, there was no significant evidence of a positive or negative effect of maximum tiller number on grain yield under rainfed conditions.

Selection criteria for drought tolerance would be helpful tools for wheat breeding programmes. To assess the usefulness of some morphological traits above the flag leaf node as indicators of yield and the susceptibility index (SI) of Fischer and Maurer, 10 durum wheat genotypes were used in experiments conducted under two water regimes at two latitudes in Spain during 3 years. Morphological traits were measured at anthesis, and yield, yield components and quality traits were evaluated at ripening. Principal components analysis showed associations between morphological traits and yield, yield components and quality, most of them caused by differences between environments. Peduncle weight, spike weight and length and awn length were significantly related to SI within environments. Spike and peduncle weight were the traits more related to yield and SI in all the experiments together and in the rainfed sites, while in the irrigated sites spike length was better. The spike weight and length were negatively associated with SI, while peduncle weight was positively associated to SI. Genotype means across all experiments were associated with SI values. These morphological traits could be selection criteria in breeding programmes to obtain varieties with good yield stability. The genetic variability found suggests opportunity for selection.

A set of ten durum wheat genotypes was grown in experiments conducted under four contrasting Mediterranean conditions during three years to assess the effect of latitude and water regime on grain growth and grain yield formation. The relationship between grain weight and accumulated growing degree-days (GDD) from anthesis was described by a logistic equation and final grain weight (W) and maximum rate (R) and duration (D) of grain filling were calculated from the fitted curves. Thousand kernel weight (TKW) was positively related to grain yield at both latitudes and water regimes, although the contribution of the number of grains per m 2 to final yield was only significant in the south, where environmental constraints likely limited the achievement of a large grain set. Differences in final grain weight between latitudes could be mostly explained by differences in the grain filling rate, while changes on W between water regimes were due to altered grain filling durations. Under northern conditions grain yield was positively associated to grain filling duration but negatively related to the maximum rate of grain filling, while in the south the coefficients of the grain filling curves had little or no effect on final yield. Reductions in grain yield under rainfed conditions were due to the fall in the number of grains per m 2 since TKW was not significantly affected by drought.

The components of grain yield are altered by adverse growing conditions as the effects of certain environmental factors on crop growth and yield differ depending upon the developmental stages when these conditions occur. Path-coefficient analysis was used to investigate the main processes influencing grain yield and its formation under Mediterranean conditions. Twenty-five durum wheat genotypes, consisting of four Spanish commercial varieties and 21 inbred lines from the ICARDA durum wheat breeding program, were grown during 1997 and 1998 under both rainfed and irrigated conditions in southern Spain. {P}ath-coefficient analysis revealed that under favourable conditions grain yield depended in equal proportion on the three primary yield components (i.e. spikes m−2, grains spike−1, and mean grain weight), whereas in the rainfed experiments, variations in grain yield were due mainly to spikes m−2 and to a lesser extent to grains spike−1. Compensatory effects were almost absent under irrigated treatments; however, under water shortage, spikes m−2 exerted a negative influence on grain spike−1 due mainly to a negative interrelationship between tiller production and apical development. These compensatory effects could partially explain the restricted success in durum wheat breeding observed in water-limited environments of the Mediterranean region. Under rainfed conditions the number of spikes m−2 depended mainly on the ability for tiller production, whereas in the irrigated experiments the final number of spikes was determined mostly by tiller survival.

Characterization of germplasm by DNA-markers provides a tool for precise germplasm identification and a quantitative assessment of genetic diversity. The genetic structure of the durum wheat germplasm grown in the Mediterranean basin varies largely from traditional landraces and cultivars characterized by a high versatility, to the modern varieties characterized by high yield potential, wide adaptation, and commercial end-use quality. The objective of this study was to assess the phylogenetic relationships among 24 durum wheat cultivars selected from relevant germplasm obtained at different periods in Italy and Spain, and to quantify the genetic erosion caused in durum wheat by breeding activities during the last century in these two countries. Genetic similarity between cultivars was studied by AFLP markers through the calculation of the Dice’s coefficient. The results showed a high degree of genetic similarity between the old Spanish cultivars and the collection of Italian cultivars, suggesting that wheat could have been introduced in the Iberian Peninsula via Italy. Genetic diversity estimates based on AFLP data confirmed the maintenance of genetic diversity with time since the values of Polymorphic Information Content were 0.27 for old cultivars (released before 1945), 0.28 for intermediate cultivars (released between 1950 and 1985) and 0.29 for modern cultivars (released between 1988 and 2000). These results indicate that genetic variability in Italian and Spanish durum wheat seems to have been maintained quite constant throughout the breeding process over the last century. # 2004 Elsevier B.V. All rights reserved.

Stability of grain quality characteristics is an interesting feature of today’s durum wheat breeding programmes, due to the high annual variation in both grain yield and quality, particularly in the Mediterranean area. Ten field trials were carried out during two seasons (1998 and 1999) in both the north (Lleida) and south (Granada and Jerez) of Spain. Ten durum wheat genotypes were used, including four Spanish commercial varieties and six advanced lines from the durum wheat breeding programme of CIMMYT-ICARDA. Many quality parameters were evaluated in this study including thousand kernel weight, test weight, vitreousness, ash content, protein content, pigment content and the SDS sedimentation test. Several statistical methods and techniques were used to describe the genotype×environment (G×E) interaction and to define stable genotypes in relation to the seven quality parameters considered in this study. The partition and interpretation of the G×E interaction revealed that the joint regression analysis was not efficient and demonstrated the usefulness of AMMI for describing the interaction patterns. The study of genotypic stability demonstrated that the Spanish commercial varieties, Altar-aos and Jabato and the CIMMYT-ICARDA advanced line, Waha, had high stability for quality characteristics and proved to be the best within the pool of the studied genotypes.

Ten durum wheat genotypes were studied in a total of 10 field trials in three different regions of Spain, associated with two latitudes (north and south) under both irrigated and rainfed conditions during the 1998 and 1999 growing seasons. Different technological and commercial quality parameters were studied: thousand kernel weight (TKW), test weight, vitreousness, ash content, protein content, pigment content and the SDS sedimentation test. The results demonstrated the strong influence of environmental conditions on the majority of quality traits in durum wheat, with growing zones, latitudes and moisture regimes showing the greatest effects. Genotypic effects were mainly observed for pigment content and SDS volume. These appear to be predominantly under genetic control. TKW and protein content were higher in Lleida in the north, probably due to the greater amount of nitrogen applied in comparison with Granada and Jerez in the south. Grain quality under the growing conditions of Lleida, however, was negatively influenced by the high percentages of ash accumulated in the grain. In general, Granada and Jerez provided an acceptable grain quality, and Jerez in particular favoured good semolina colour and higher test weights. Moisture stress increased mainly protein content and vitreousness, and reduced TKW and ash content at both latitudes. It is clear that rainfed conditions in the south offer the best opportunity for production of durum wheat of good quality.

The unpredictability of the Mediterranean climate causes fluctuations in wheat yield and quality, but oAers the opportunity for obtaining high-quality durum wheat in terms of grain protein content. Twentyfive durum wheat genotypes were grown under irrigated and rainfed conditions at each of two latitudes in Spain during 1998 and 1999. DiAerences between latitudes in grain protein content and chlorophyll content in the flag leaf were attributable to nitrogen fertilization management. Cycle length until anthesis was less aAected by the environment than grain-filling duration, and was longer under irrigated conditions than in the rainfed sites. A negative asymptotic curve was the best equation to fit the relationship between yield and protein content, suggesting that yield improvements in fertile environments may be attained with negligible reductions in protein content.

Amino acid composition is an important feature in determining the nutritional value of wheat grain for human and animal diets. Environmental conditions are known to influence protein quantity as well as grain production and, in turn, amino acid composition. In this study, grain yield, protein content, and amino acid composition were determined in 10 durum wheat genotypes under three water and temperature regimes in a Mediterranean environment. The highest value for grain-protein content (15.7%) was found in the warmer and driest environment and the lowest (12.8%) in the irrigated environment. Although amino acid composition showed significant variation for all genotypes, with the exception of arginine and cysteine, major changes in amino acid composition were caused by environmental conditions and in particular by water availability and temperature during the grain-filling period, which significantly altered the duration of grain development. The amino acids with the highest percentage of variation between environments were tyrosine (26.4%), lysine (23.7%), methionine (20.3%), threonine (19.3%), and valine (15.6%), whereas phenylalanine (5.1%), glycine (6.4%), and aspartic acid (6.8%) showed the least variation between environments. Whereas the content of glutamine, phenylalanine, and proline increased with the decrease in grain-filling duration, the remaining amino acids tended to diminish, presumably because high temperature and drought favored the deposition of gliadins (proteins particularly rich in glutamine and proline), to the detriment of albumins and globulins (proteins especially rich in threonine, lysine, methionine, valine, and histidine). Despite the negative correlations found between the percentage of protein and its content in essential amino acids, the results indicate that reductions in lysine per unit of food were not very pronounced (0.32 to 0.29 g/100 g of flour) with increases of up 22.7% in grain-protein content, whereas threonine did not change and valine even slightly increased.

A major problem for durum wheat production in the Mediterranean region is yield fluctuation. This fluctuation is a result of year-to-year variation in precipitation and heat stress during grain growth, which is typical of the Mediterranean climate. Both yield stability and good quality are needed in adapted durum wheat ideotypes. Ten durum wheat cultivars differing in drought resistance were grown during 1998, under both rainfed and irrigated conditions, at three sites in southern Spain. The main traits studied were protein and lysine content, grain yield, test weight, SDS sedimentation, semolina color, and grain vitreousness. Results show a high influence of site on all traits. Only test weight (TW), SDS sedimentation, grain vitreousness, and protein per kernel appeared to be determined also by cultivar effect. Vitreousness was positively correlated with TW (r = 0.48**) and semolina color (r = 0.46**). An inverse relationship was found between grain yield and protein content. Regression of cultivar mean values of protein content and grain yield showed a negative correlation (r = -0.72***), probably due to dilution of protein by non-nitrogen compounds and reduced starch accumulation in the grain under drought conditions. Lysine content was negatively associated with protein content (r = -0.86***), indicating the difficulty of a simultaneous breeding for both characteristics.

This study evaluates the breeding of durum wheat (Triticum turgidum L. var. durum) during the 20th century with respect to yield and grain carbon isotope discrimination (A), and their relationship with plant height, harvest index (HI), days from sowing to anthesis, and days from anthesis to maturity. Twenty-four cultivars released before 1945 (old), between 1950 and 1985 (intermediate), and between 1988 and 2000 (modern), and previously characterized by whether dwarfing genes were present (semidwarf) or absent (tall), were selected from germplasm obtained in Italy and Spain. Experiments were conducted in six environments with average yields ranging from to 2113 to 4827 kg ha -1 . The total absolute genetic gain in yield across countries from before 1945 to 2000 was 20 kg ha -1 yr -1 (51% of increase), which represents a relative genetic gain of 0.61% yr -1 . Yield gains led to a loss of stability. The mean increase in Δ 13 C was 6% (0.014%o yr -1 or 0.09% yr -1 ). Early heading and a long grain-filling period were correlated with high yields in the tall cultivars. Increased plant height and low Δ 13 C values were associated with high yields for the semidwarf cultivars, while a long grain-filling period was not advantageous for semidwarf cultivars.

The relationships between carbon isotope discrimination (∆) in mature kernels, canopy temperature depression (CTD) during anthesis and grain filling, 1000-kernel weight (TKW), total carbon content of mature kernels, and yield were studied in durum wheat (Triticum turgidum L. var. durum) grown in Spain (western Mediterranean basin). Twenty-five durum wheat genotypes were grown in 2 regions (NE and SE Spain) and under 2 water regimes (rainfed v. support irrigation) from 1997 to 1999 (i.e. a total of 12 trials). Principal component analysis placed yield and ∆ on the same axis. Pearson's correlation and stepwise analysis confirmed that ∆ was the trait that best assessed genotype differences in yield within trials, and was followed, at a considerable distance, by TKW. Our results also demonstrated the extremely poor performance of CTD throughout the wide range of growing conditions in this study. Additional keywords: drought, kernel weight, kernel carbon content. I imnper A

Grain yield of durum wheat (Triticum turgidum L. var. durum) under Mediterranean conditions is frequently limited by both high temperature and drought during grain growth. Path coefficient analyses, based on an ontogenetic diagram, were conducted to study grain yield formation under different temperature and moisture regimes across Spain. Six ICARDA-CIMMYT inbred lines and four Spanish commercial cultivars were grown during 1998 and 1999 at two temperature regimes (cool and warm) and under both rainfed and irrigated conditions. Path coefficient analysis revealed that grain yield under cooler conditions was mostly determined by kernel weight, whereas the number of spikes per square meter predominantly influenced grain production in the warmer environments. The number of kernels per spike had a significant contribution to grain yield, especially under drought stress conditions. These associations do not clearly appear in the simple correlation analysis. Compensatory effects among yield components were almost absent in the cooler environments, probably due to the relative availability of water and N during the critical phases of plant development. Contrarily, under warmer conditions, negative effects of the number of spikes per square meter were registered on both the number of kernels per spike and kernel weight. Path analysis appears to be a useful tool for understanding grain yield formation and provides valuable additional information for improving grain yield via selection for its yield components.

The effect of environment on the relationship between grain carbon isotope discrimination (Δ) and yield was studied for durum wheat (Triticum turgidum L. var. durum) under Mediterranean conditions. A group of 25 genotypes was grown under contrasting water regimes in two regions of Spain during three years. The first objective was to determine the environmental factors responsible for the strong positive relationship previously observed between Δ and yield across trials. Environmental factors tested were total water input (W i ), mean temperature, accumulated reference evapotranspiration (ET,), and the ratio W i /ET 0 during different periods of the crop cyde. Water input during grain filling was the variable most strongly correlated with grain A and yield across all the trials, as well as across the subset of trials in northeastern Spain. In southeastern Spain, the most drought prone of the two regions, W i from sowing to heading explained the most variation in grain Δ and yield. The second objective was to study the effect of environment on the relationship between A and yield across genotypes. No significant correlation was found for trials with a mean yield up to about 2000 kg ha -1 , but the strength of the relationship increased sharply and attained significance in trials yielding 2500 kg ha -1 . When yield above 2500 kg ha -1 the correlation between A and yield remained relatively steady and positive, with an r value around 0.5. It is concluded that breeding to raise durum wheat yield in Mediterranean conditions could take advantage of selecting for higher A only in relatively wet years or under supplementary irrigation.