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This article belongs to the Special Issue Crop Tolerance under Biotic and Abiotic Stresses [Abstract] Drought is a major abiotic stress that greatly affects canola growth, production, and quality. Moreover, water scarcity is projected to be more severe and frequent as a result of climate change, in particular in arid environments. Thereupon, developing drought-tolerant and high-yielding canola genotypes has become more critical to sustaining its production and ensuring global food security with the continuing population growth. In the present study, ten canola genotypes comprising six developed tissue-cultured canola genotypes, two exotic genotypes, and two commercial cultivars were evaluated under four irrigation regimes. The applied irrigation regimes were well-watered (100% crop evapotranspiration, ETc), mild drought (80% ETc), moderate drought (60% ETc), and severe drought (40% ETc) conditions. Drought-stress treatments (80, 60, and 40% ETc) gradually reduced the chlorophyll content, relative water content, flowering time, days to maturity, plant height, number of pods, number of branches, seed yield, and oil percentage, and increased proline, phenolic, anthocyanin, and glycine betaine contents. The evaluated genotypes exhibited varied responses to drought-stress conditions. The developed tissue-cultured genotypes T2, T3, and T1, as well as exotic genotype Torpe, possessed the highest performance in all evaluated parameters and surpassed the other tested genotypes under water-deficit conditions. Overall, our findings elicited the superiority of certain newly developed tissue-cultured genotypes and exotic ones compared with commercial cultivars, which could be exploited in canola breeding under water-deficit conditions. This research was funded by the Researchers Supporting Project number (RSPD-2023R730), King Saud University, Riyadh, Saudi Arabia King Saud University (Riad, Arabia Saudí); RSPD-2023R730

Wheat landraces are valuable genetic resource for diversity and specific adaptation to local environmental conditions as well as increasing agronomic traits in breeding programs. Admittedly, this type of genotypes has become more crucial to face the challenges of recent climate change. The aim of this study was to investigate the genetic diversity among Egyptian bread wheat landraces and commercial cultivars based on morpho-phenological and agronomic characters. Thirty-two wheat landraces were collected from eleven Egyptian provinces through collecting trips during 1987 to 1999 and, in addition, three commercial cultivars were evaluated all for fifteen qualitative and quantitative characters. Wide genetic diversity was detected based on evaluated morphological characters was observed among the landraces compared to commercial cultivars. Various landraces exhibited strong glaucosity on flag leaf, culm and ear, which is crucial character especially under dry and hot cultivation conditions as Mediterranean region. Furthermore, considerable variation among tested genotypes was demonstrated on the basis of yield-related traits and they were classified into four groups (A–D) from very high-yielding to low-yielding genotypes. Wheat landraces number 3, 8, 14, 27, 29, 33 and 35 exhibited superiority for earliness, grain yield/plant and its components compared to commercial cultivars (number 18, 19 and 20). The association among morpho-phenological and agronomic characters was studied according to principal component analysis. The evaluated characters were divided into four groups. Certain morphological characters (coleoptiles anthocyanin coloration and awns or scurs at tip of ear length) alongside the phenological characters (days to heading and maturity) and certain agronomic characters (plant height and 1000-grain weight) displayed strong association with grain yield/plant. Furthermore, estimated broad sense heritability was high for plant height, number of grains/spike, 1000-grain weight, days to heading, moderate for days to maturity and grain yield/plant presented and low for number of spikes/plant.

Polyamines (PAs) are plant growth regulators that attenuate the destructive impacts of water deficit on sesame plants, particularly in arid regions under abrupt climate change. Limited information is available on the physiological, biochemical, anatomical, and agronomic responses of sesame to exogenous application of PAs under water deficit under field conditions. Thus, a two-season field trial was carried out to assess the impact of exogenously sprayed spermine (Spm), spermidine (Spd), and putrescine (Put) on physio-biochemical and anatomical parameters and their influences on agronomic performance and crop water productivity of sesame plants. The sesame plants were assessed under three irrigation regimes; full irrigation (100% ETc), mild drought (75% ETc), and severe drought (50% ETc) conditions. Drought stress displayed negative impacts on all evaluated parameters. However, exogenously applied Pas, especially Put, restricted the destructive effects of water deficit. The application of PAs exhibited highly significant enhancement in photosynthetic pigments (chlorophyll a, b, and carotenoids), gas exchange (net photosynthetic rate, stomatal conductance, and rate of transpiration), water relations (relative water content, membrane stability index, excised leaf water retention), and plant nutrient content (N, P, and K) compared to untreated plants, particularly under severe drought stress. Moreover, PA application displayed highly significant amelioration in osmoprotectants (free proline, soluble sugars, α-Tocopherol, ascorbate, and glutathione), and antioxidant enzyme activities (catalase, peroxidase, superoxide dismutase, ascorbate peroxidase, and glutathione reductase). In addition, foliar nourishing with PAs exhibited a highly significant reduction in oxidative stress markers (malondialdehyde, electrolyte leakage, superoxide, and hydrogen peroxide). These positive impacts of PA application under drought stress were reflected in highly significant improvement in anatomical characteristics (midrib length and width, vascular bundle length and width, thickness of phloem, xylem and collenchyma, vessel diameter, and number of xylem rows in midvein bundle), and yield-related traits (plant height, leaf area, number of capsules per plant, 1000-seed weight, seed yield, and oil content). Consequently, exogenous application of PAs (in particular, Put) could be exploited to enhance the crop water productivity and yield traits of sesame plants under low water availability in arid regions.

11 Pags.- 7 Figs.- 4 Tabls., Salinity is one of the most widespread abiotic stresses affecting crop growth and productivity, particularly when soil and irrigation water are salty. Field experiments were performed in an arid Mediterranean climate to investigate agronomic responses of twenty-one diverse barley genotypes to naturally occurring salinity. Three saline fields (7.72 dS/m) were irrigated with well water of three incremental salinity levels, low (5.25 dS/m), intermediate (8.35 dS/m), and high (11.12 dS/m). The results revealed considerable genotypic variability at the three salinity levels and significant genotype by salinity interaction that could be traced to specific yield components. Increasing salinity level decreased performance of all agronomic traits, but with different patterns, with yield components determined earlier being more affected than traits determined later. Days to heading exhibited a strong and negative relationship with grain yield across all salinity levels, while 1000-grain weight demonstrated the highest association with grain yield, followed by number of grains per spike, plant height, and harvest index, consistently at the three salinity levels. The genotypes were classified based on their yield indices at the three salinity levels into six groups varying from highly salt-tolerant (group A) to highly salt-sensitive genotypes (group F). Genotype-by-salinity interaction was studied based on rankings of performance across salinity levels. Close examination of yield component trends across levels allowed the identification of genotypes with different behaviors, indicating the presence of variation in potentially different mechanisms of response to salinity. This diversity of responses could be used in breeding to improve tolerance over the whole crop cycle, from plant establishment and tillering to grain filling.

Hybrid rice seed production predominantly relies on the pollen ability of restorer lines and the stigma properties of the cytoplasmic male sterile (CMS) lines. Improving the pollen ability and agronomic performance of restorer lines could be achieved using mutation to reinforce the outcrossing rate and seed set percentage of CMS lines. Two commercial restorer cultivars (Giza-178 and Giza-179) were treated with three different doses of gamma-ray; 200, 300, and 400 Gy. The derived mutant restorer lines were selfed and constantly evaluated with their corresponding parental cultivars until the M6 generation. Six promising mutant lines were chosen based on their performance to be evaluated with their parents for their pollen and agronomic characteristics. The novel-induced mutant restorer lines exhibited significant differences in all studied pollen and agronomic characteristics. The mutant restorer lines R4 and R7 exhibited superior desirable anther length (2.36 and 2.38 mm, in the same order), anther width (0.47 and 0.45 mm), pollen fertility (97.50 and 97.31%), basal pore length (218.8 and 299.5 mm), apical length (103.6 and 108.1), number of pollen grains per anther (1810 and 1832), plant height (121.8 and 115.9 cm), fertile tillers (23.50 and 18.89), number of spikelets per panicle (203.2 and 202.5), panicle length (25.34 and 24.26 cm), number of filled grains per panicle (195.5 and 191.8), seed set percentage (95.56 and 96.63%), and grain yield (11.01 and 11.36 t/ha). Based on the results of the first two seasons, the two novel promising restorers and their parental cultivars were crossed with four diverse CMS lines. The seed set percentage and hybrid seed production of the crossed CMS lines were evaluated for further two seasons. The results exposed that the combinations derived from restorer lines R4 and R7 with most of the evaluated CMS lines produced the uppermost seed set percentage outcrossing rate. Particularly in combination with CMS2, the restorer lines R4 and R7 displayed the highest seed set percentage (39.57 and 34.80%), number of tillers fertile per hill (25.31 and 23.32), seed yield (2.02 and 1.81 t/ha), and harvest index (23.88 and 22.66%). Conclusively, the derived gamma-ray-induced mutant restorer lines R4 and R7 could be exploited as a new source for ensuring desirable pollen and anther characteristics in order to improve the outcrossing rate of CMS lines and hybrid rice seed production.

High temperature is a major environmental stress that devastatingly affects wheat production. Thenceforth, developing heat-tolerant and high-yielding wheat genotypes has become more critical to sustaining wheat production particularly under abrupt climate change and fast-growing global population. The present study aimed to evaluate parental genotypes and their cross combinations under normal and heat stress conditions, exploring their diversity based on dehydration-responsive element-binding 2 gene (DREB, stress tolerance gene in response to abiotic stress) in parental genotypes, and determining gene action controlling yield traits through half-diallel analysis. Six diverse bread wheat genotypes (local and exotic) and their 15 F1 hybrids were evaluated at two different locations under timely and late sowing dates. Sowing date, location, genotype, and their interactions significantly impacted the studied traits, days to heading, chlorophyll content, plant height, grain yield, and its attributes. Cluster analysis classified the parents and their crosses into four groups varying from heat-tolerant to heat-sensitive based on heat tolerance indices. The parental genotypes P2 and P4 were identified as an excellent source of beneficial alleles for earliness and high yielding under heat stress. This was corroborated by DNA sequence analysis of DREB transcription factors. They were the highest homologies for dehydrin gene sequence with heat-tolerant wheat species. The hybrid combinations of P1 × P5, P1 × P6, P2 × P4, and P3 × P5 were detected to be good specific combiners for grain yield and its attributes under heat stress conditions. These designated genotypes could be used in wheat breeding for developing heat-tolerant and climate-resilient cultivars. The non-additive genetic variances were preponderant over additive genetic variances for grain yield and most traits under both sowing dates. The narrow-sense heritability ranged from low to moderate for most traits. Strong positive associations were detected between grain yield and each of chlorophyll content, plant height, number of grains/spike, and thousand-grain weights, which suggest their importance for indirect selection under heat stress, especially in early generations, due to the effortlessness of their measurement.

Salinity is a major abiotic stress that poses great obstacles to wheat production, especially in arid regions. The application of exogenous substances can enhance plant salt tolerance and increase its productivity under salinity stress. This work aimed to assess the mechanisms of selenium (Se) at different concentrations (2, 4 and 8 μM SeCl2) to mitigate hazardous impacts of salt toxicity at physiological, biochemical and agronomic levels in bread wheat. The results displayed that Se foliar application increased chlorophyll content, net photosynthetic rate, transpiration rate, stomatal conductance, relative water content, membrane stability index, excised leaf water retention, proline, total soluble sugars, Ca content, K content, antioxidant enzyme activities and non-enzymatic antioxidant compounds compared to untreated plants. On the other hand, Se application decreased the content of Na, hydrogen peroxide and superoxide contents. Accordingly, our findings recommend exogenous Se application (in particular 8 μM) to alleviate the deleterious effects induced by salinity stress and improve wheat yield attributes through enhancing antioxidant defense systems and photosynthetic capacity.

Salinity in soil or irrigation water requires developing genetically salt-tolerant genotypes, especially in arid regions. Developing salt-tolerant and high-yielding wheat genotypes has become more urgent in particular with continuing global population growth and abrupt climate changes. The current study aimed at investigating the genetic variability of new breeding lines in three advanced generations F6–F8 under salinity stress. The evaluated advanced lines were derived through accurate pedigree selection under actual saline field conditions (7.74 dS/m) and using saline water in irrigation (8.35 dS/m). Ninety-four F6 lines were evaluated in 2017–2018 and reduced by selection to thirty-seven F7 lines in 2018–2019 and afterward to thirty-four F8 lines in 2019–2020 based on grain yield and related traits compared with adopted check cultivars. Significant genetic variability was detected for all evaluated agronomic traits across generations in the salt-stressed field. The elite F8 breeding lines displayed higher performance than the adopted check cultivars. These lines were classified based on yield index into four groups using hierarchical clustering ranging from highly salt-tolerant to slightly salt-tolerant genotypes, which efficiently enhance the narrow genetic pool of salt-tolerance. The detected response to selection and high to intermediate broad-sense heritability for measured traits displayed their potentiality to be utilized through advanced generations under salinity stress for identifying salt-tolerant breeding lines.

Improved water use efficiency (WUE) for barley (Hordeum vulgare L.) production in the arid and semiarid regions is necessary to save the limited water resources available for irrigation. A field study was conducted in 2014–2015 and 2015–2016 growing seasons on sandy soil under drip irrigation system. Objectives were to identify drought-tolerant genotypes of barley that are less susceptible to water stress and determine the impact of various irrigation levels on yield attributes, grain yield, WUE of those genotypes compared with drought-sensitive genotypes in an arid Mediterranean latitude. Treatments included four irrigation levels (severely-low 120mm, low 240mm, medium 360mm, and high 480mm) and seventeen barley genotypes. Plants exposed to water stress showed significant plant height and yield attributes decrease compared with well-watered plants. The high irrigation level had the greatest grain yield of 4284kgha−1 and lowest WUE of 6.7kgha−1mm−1. The WUE of aboveground biomass was also decreased to 16.2kgha−1mm−1 for the high irrigation level compared with 28.3kgha−1mm−1 for the severely-low irrigation level. Drought-tolerant genotypes managed to produce more yield with higher WUE compared with drought-sensitive genotypes. Maximum grain yield of 4966kgha−1 was obtained at 482mm of irrigation water for drought-tolerant genotypes while drought-sensitive genotypes had maximum grain yield of 3513kgha−1 at 561mm of irrigation water. These results suggest that improved irrigation management using drip irrigation system and the use of drought-tolerant genotypes can increase water productivity to conserve the limited water resources in arid Mediterranean environments.

SUMMARYAgricultural practices are likely to lower nitrogen (N) fertilization inputs for economic and ecological limitation reasons. The objective of the current study was to assess genotypic variation in nitrogen use efficiency (NUE) and related parameters of spring wheat (Triticum aestivumL.) as well as the relative grain yield performance under sandy soil conditions. A sub-set of 16 spring wheat genotypes was studied over 2 years at five N levels (0, 70, 140, 210 and 280 kg N/ha). Results indicated significant differences among genotypes and N levels for grain yield and yield components as well as NUE. Genotypes with high NUE exhibited higher plant biomass, grain and straw N concentration and grain yield than those with medium and low NUE. Utilization efficiency (grain-NUtE) was more important than uptake efficiency (total NUpE) in association with grain yield. Nitrogen supply was found to have a substantial effect on genotype; Line 6052 as well as Shandawel 1, Gemmiza 10, Gemmiza 12, Line 6078 and Line 6083 showed higher net assimilation rate, more productive tillers, increased number of spikes per unit area and grains per spike, extensive N concentration in grain and straw, heavier grains, higher biological yield and consequently maximized grain yield. The relative importance of NUE-associated parameters such as nitrogen agronomic efficiency, nitrogen physiological efficiency and apparent nitrogen recovery as potential targets in breeding programmes for increased NUE genotypes is also mentioned.

Drought is one of the major threats to global food security. Biochar use in agriculture has received much attention and improving it through chemical modification offers a potential approach for enhancing crop productivity. There is still limited knowledge on how acidified biochar influences soil properties, and consequently its influences on the agricultural productivity of drought stressed plants. The water use efficiency (I-WUE) of drought stressed faba beans was investigated through the effects of acidified biochar (ACBio) (a 3:100 (w:w) combination of citric acid and biochar) on soil properties, growth, productivity, nutrient uptake, water productivity (WP), and irrigation. Two field experiments (2016/2017 and 2017/2018) were conducted in saline soil (ECe, 7.2 dS m−1) on faba been plants grown under three irrigation regimes (i.e., 100, 80, and 60% of crop evapotranspiration (ETc)) combined with three levels of ACBio (0, 5, and 10 t ha−1). Plants exposed to water stress presented a significant decrease in plant height, dry matter, leave area, chlorophyll content (SPAD), the quantum efficiency of photosystem II (Fv/Fm, Fv/F0, and PI), water status (membrane stability index and relative water content), and seed yield. Acidified biochar soil incorporation improved soil properties (chemical and physical), plant growth, physiological responses, WP, I-WUE, and contents of N, P, K, and Ca. Results revealed that the application of ACBio at 10 t ha−1 and 5 t ha−1 significantly increased seed yield by 38.7 and 25.8%, respectively, compared to the control. Therefore, ACBio incorporation may find application in the future as a potential soil amendment for improving growth and productivity of faba bean plants under deficit irrigation.

Late wilt disease (LWD) caused by the fungus Magnaporthiopsis maydis poses a major threat to maize production. Developing high-yielding and resistant hybrids is vital to cope with this destructive disease. The present study aimed at assessing general (GCA) and specific (SCA) combining abilities for agronomic traits and resistance to LWD, identifying high-yielding hybrids with high resistance to LWD, determining the parental genetic distance (GD) using SSR markers and investigating its relationship with hybrid performance and SCA effects. Ten diverse yellow maize inbred lines assembled from different origins and three high-yielding testers were crossed using line × tester mating design. The obtained 30 test-crosses plus the check hybrid TWC-368 were evaluated in two field trials. Earliness and agronomic traits were evaluated in two different locations. While resistance to LWD was tested under two nitrogen levels (low and high levels) in a disease nursery that was artificially infected by the pathogen Magnaporthiopsis maydis. Highly significant differences were detected among the evaluated lines, testers, and their corresponding hybrids for most measured traits. The non-additive gene action had more important role than the additive one in controlling the inheritance of earliness, grain yield, and resistance to LWD. The inbred lines L4 and L5 were identified as an excellent source of favorable alleles for high yielding and resistance to LWD. Four hybrids L5 × T1, L9 × T1, L4 × T2, and L5 × T2, exhibited earliness, high grain yield, and high resistance to LWD. Parental GD ranged from 0.60 to 0.97, with an average of 0.81. The dendrogram grouped the parental genotypes into three main clusters, which could help in reducing number of generated crosses that will be evaluated in field trials. SCA displayed significant association with the hybrid performance for grain yield and resistance to LWD, which suggests SCA is a good predictor for grain yield and resistance to LWD.

Water shortage is a major environmental stress that destructively impacts maize production, particularly in arid regions. Therefore, improving irrigation management and increasing productivity per unit of water applied are needed, especially under the rising temperature and precipitation fluctuations induced by climate change. Laboratory and field trials were carried out in the present study, which were aimed at assessing the possibility of promoting maize germination, growth, grain yield and crop water productivity (CWP) using seed priming under different irrigation regimes. Two seed priming treatments, i.e., hydro-priming and hardening versus unprimed seeds, were applied under four irrigation regimes, i.e., 120, 100, 80 and 60% of estimated crop evapotranspiration (ETc). The obtained results indicated that increasing irrigation water from 100% up to 120% ETc did not significantly increase grain yield or contributing traits, while it decreased CWP. Deficit irrigation of 80 and 60% ETc gradually decreased grain yield and all attributed traits. Seed priming significantly ameliorated seedlings’ vigor as indicated by earlier germination, higher germination percentage, longer roots and shoots, and heavier fresh and dry weight than unprimed seeds with the superiority of hardening treatment. Additionally, under field conditions, seed priming significantly increased grain yield, yield contributing traits and CWP compared with unprimed treatment. Interestingly, the results reflect the role of seed priming, particularly hardening, in mitigating negative impacts of drought stress and enhancing maize growth, grain yield and attributed traits as well as CWP under deficit irrigation conditions. This was demonstrated by a significant increase in grain yield and CWP under moderate drought and severe drought conditions compared with unprimed treatment. These results highlight that efficient irrigation management and seed priming can increase maize yield and water productivity in arid environments.

Dual-purpose barley is an alternative approach to producing high-quality forage yield plus an acceptable grain yield in marginal environments of arid regions that are characterized by lack of forage. Field experiment was performed in two consecutive growing seasons at an arid region affected by salinity in irrigation water and soil at Western Sinai Peninsula in Egypt. The study aimed to optimize sowing date and screen salt-tolerant barley genotypes that perform better in terms of forage yield and quality as well as grain and biomass yield production in salt-affected environment. Sowing dates, genotypes, and their interaction significantly impacted most of the studied variables such as forage yield, crude protein yield, and grain and biomass yields. The early sowing in late October yielded higher than intermediate sowing in mid-November and late sowing in early December. Some of the tested genotypes performed better than others as indicated by about 50% higher forage yield, 6% crude protein content, 39% grain and 21% biological yields (total aboveground dry matter), suggesting higher adaptation capacity. Interestingly, grain and biological yields did not differ significantly between dual-purpose approach and grain-only pattern. In conclusion, dual-purpose barley was found favorable for producing grain and forage production in similar environments under early sowing date.

Faba bean (Vicia faba L.), a major legume crop, helps in maintaining soil health by fixing atmospheric nitrogen (N2) and thus mostly used as a rotational crop. However, faba bean is sensitive to water stress, which limits its yield potential in water-limited environments. The objectives of the present study were to (i) characterize the agro-physiological performance of 14 faba bean genotypes with different genetic backgrounds to various levels of water stress in an arid environment and (ii) identify the most drought-tolerant genotypes that maximize the marginal use of unit water without significant yield loss. Field experiments were conducted for two consecutive growing seasons in an arid Mediterranean climate, and several agronomic and physiological measurements of different faba bean genotypes in response to water stress were recorded. A great variation among the tested genotypes, according to several drought-response indices, was observed as a result of water stress on the basis of which they were classified into five groups (A–E) ranging from drought-tolerant to highly sensitive genotypes. Yield and water productivity results indicated that drought-tolerant genotypes produced more yield with less water compared with drought-sensitive genotypes and thus are highly recommended for faba bean production in water-limited environments. Certain physiological parameters, such as photosynthetic pigment, net photosynthetic rate, transpiration rate, leaf nutrient status (N, P and K content), relative water content and membrane stability index, exhibited highly positive association with seed yield and yield contributing traits. It is valid to use these parameters as rapid indicators of drought tolerance in breeding programs aiming to screen and improve faba bean genotypes for drought tolerance in arid environments.

Crop models may potentially explore alternative ways to improve agroecosystem resilience in arid regions of Middle East and North Africa. Mapping the outputs behavior as a function of the inputs and quantifying the uncertainty contribution of inputs to the variability of outputs are crucial for understanding and applying complex mathematical models to a new environment. Objectives of present research are (i) to calibrate and evaluate the Decision Support System for Agrotechnology Transfer (DSSAT) cropping system model using detailed experimental datasets on maize production in arid sandy soils (Entisol) and (ii) to determine the model’s sensitivity to soil, genotype and crop management inputs under the currently explored conditions (low fertility and water holding capacity) based on multivariate analysis and variance decomposition methods. The goodness-of-fit statistics between observed and simulated data indicated that the calibrated model reasonably well simulates maize phenology, growth and yield, evapotranspiration, soil water content, grain N concentration, and postharvest soil NO3-N in eight year site field experiments. A global sensitivity analysis using the co-inertia method was carried out to link 14 output variables and 25 soil and genotype input parameters. Maize growth and yield variables were strongly correlated with soil hydrological and fertility input parameters such as soil water upper limit (SDUL) and soil organic carbon (SOC), whereas simulation of maize phenology was largely determined by phenological genotype-specific cultivar input parameters. A strong association was also observed between the output variables of yield and soil fertility. The effect of carbon (C) related soil input parameters of initial SOC and stable SOC and crop management factors of maize residue retention and compost application under no-till system on the long-term (10 years) simulation of yield and SOC dynamics was further explored using Sobolʹ method. Simulated grain yield, water productivity, active SOC, and cumulative soil CO2 efflux were most sensitive to initial stable SOC and compost application. Maize residue retention significantly affected the simulation of cumulative N mineralization, SOC % in 0.2 m depth, and cumulative soil CO2 efflux through interactions effect, i.e. total-order sensitivity index (STi) > 0.05, with other inputs. Compost application increased grain yield by 13 %, SOC stock by 5%, and cumulative soil CO2 efflux by 95 % compared with no application. However, compost application with maize residue retained significantly reduced cumulative soil CO2 efflux by 12 % compared with compost application with maize residue removed. Therefore, the application of compost with maize residue retained under no-till system is a plausible crop management option for agronomically improved and environmentally sound maize production in arid sandy soils.

Aim of study: To explore the role of ascorbic acid (AsA) or silicon (Si) in improving drought tolerance in five faba bean cultivars under irrigation water deficit (IWD).Area of study: The experimental farm; 30° 36′ N, 32° 16′ E, Egypt.Material and methods: Three drip irrigation regimes (WW, well-watered, 4000 m3 water ha-1; MD, moderate drought, 3000 m3 water ha-1; and SD, severe drought, 2000 m3 water ha-1) were applied to plants, which were sprayed 25, 40, and 55 days after sowing with 1.5 mM AsA or 2.0 mM Si vs distilled water as a control.Main results: Drought negatively affected physiological attributes (photosynthetic pigments, gas exchange parameters, relative water content, membrane stability index, electrolyte leakage (EL), and lipid peroxidation), which restricted plant growth and yields, and stimulated alterations in both enzymatic and non-enzymatic antioxidant activities. However, AsA or Si application mitigated drought effects on physiological attributes, improving growth, yields and water use efficiency by raising antioxidant activities and suppressing lipid peroxidation and EL in stressful cultivars. The mitigating effects of AsA and Si were more pronounced under MD.Research highlights: ‘Nubaria-2’, ‘Giza-843’, and ‘Sakha-3’ were more tolerant than ‘Giza-716’ and ‘Sakha-4’, suggesting the use of AsA or Si to ameliorate the IWD effects on stressful cultivars. Certain physiological traits exhibited positive association with growth and seed yield, demonstrating their importance in enhancing seed yield under irrigation treatments.

41 Pags.- 14 Tabls.- 5 Figs. The definitive version is available at: https://www.sciencedirect.com/science/journal/03784290, Climate change poses challenges to agricultural production in general and to plant breeders in particular. Adaptation of cereals to the new conditions and increasingly variable situations arising from this process is essential to reduce risks and limit potential threats associated with climate hazards. This study presents the first attempt to assess the response and resilience of barley genotypes, with different growth habits across Egypt. For this purpose, eight field trials were conducted from 2013 to 2016 at three experimental sites with different winter climate configurations. The trials were sown at the end of November, following recommendations for the region. Fourteen barley genotypes were evaluated, comprising seven commercial Egyptian cultivars and seven European genotypes. The European genotypes were selected from successful cultivars from Spain, encompassing a range of growth types: two spring, three intermediate and two winter types. The cultivars were genotyped for six major adaptation genes, Vrn-H1-2-3, Ppd-H1-2 and HvCEN. One interesting finding is that, while the Egyptian cultivars were assumed to be of spring growth type, our results demonstrate that two cultivars, namely Giza123 and Giza126, are actually intermediate types (needing just a short period of vernalization). They contain the winter allele at Vrn-H2 together with Vrn-H1-4, the same as the European genotypes Cierzo and Orria, they also have an active allele at PpdH2, such as Hispanic. Overall, these four genotypes showed very good performance in all trials with low genotype-by-environment interaction. Moreover, a foreign late spring genotype (Pewter) was highly productive and a winter genotype (Hispanic) flowered as early as some intermediate and spring genotypes with a yield similar to genotypes currently grown in Egypt. A possible explanation for this surprising occurrence, the influence of an active allele at PpdH2 in winter cultivars, is discussed. In relation to low temperature, a high frequency of cold nights during wintertime was observed at all experimental sites, which seemed sufficient to promote timely flowering for intermediate genotypes, although this was inadequate for promoting flowering and achieving good productivity in strictly winter genotypes (e.g. Barberousse). Our findings also highlight the potential of exotic germplasm for breeding better and more resilient cultivars for autumn and for achieving good yield levels in regions with warm winters like Egypt. The results also provide insights into the usefulness of genetic variation in growth habit for breeders seeking adaptation to climate change conditions., AMC and EI acknowledge funding from Spanish MINECO, grants AGL2013-48756-R and AGL2016-80967-R.

17 Pags.- 5 Tabls. The definitive version is available at: http://www.publish.csiro.au/cp, Identifying stable, high-yielding genotypes is essential for food security. This is particularly relevant in the current climate change scenario, which results in increasing occurrence of adverse conditions in the Mediterranean region. The objective of this study was to evaluate stability of barley (Hordeum vulgare L.) grain yield, and its relationship to the duration of the growth cycle and its stability under Mediterranean conditions in Egypt. Nineteen genotypes were evaluated during three growing seasons (2013–14 to 2015–16) at two locations (Elkhatara, Ghazala) and two growing seasons (2014–15 and 2015–16) at a third location (Ras-Sudr), i.e. eight environments (location–year combinations) in total. The linear regression explained a significant 48.2% and 22.8% of GEI variation for days to heading and grain yield, respectively, and the genotypic linear slopes were highly related to the first principal component of the AMMI model. Although all genotypes were well adapted to the region, there were different GEI responses, with changes in ranking across locations. Some stable and broadly adapted genotypes were identified, as well as unstable genotypes with specific adaptations. High yields across environments were attained by very stable (G4, G5), intermediate and stable (G1, G9) and highly responsive (G18, G19) genotypes. In general, responsiveness (b values) of yield and days to heading were negatively correlated, and high yielding genotypes showed different patterns of responses of days to heading. Genotypes G1, G4, G5 and G9 seemed best adapted overall, with longer season genotypes (e.g. G18 and G19) offering prospects to explore other formats of varieties in breeding, particularly for situations of climate instability.

29 Pags.- 4 Tabls.- 1 Fig. The definitive version is available at: http://link.springer.com/journal/11032, This study is a retrospective analysis of an elite cross from the Spanish National Barley Breeding Program. This was the most successful cross produced in the breeding program in the past 20 years. The progeny from this cross has been investigated at two points in the program, before and after selection, through the analysis of allelic frequencies at a number of genetic loci with molecular markers. Shifts in allelic frequencies after selection allowed the identification of genomic regions with selection footprints likely due to the breeding process. The cross was replicated in three different years, and therefore, the three progenies represent different selection histories but, in all cases, were preferentially selected compared to the lines from other crosses used in the program. The progenies were sampled at two generations, before conscious selection (F2) and after six generations of selection (F8). The F2 plants were genotyped with microsatellites, whereas 31 F8 lines were surveyed for SNP and presence/absence variation polymorphisms using a genotyping-by-sequencing system (DArTseq). The DArTseq markers were aligned to the barley physical map, and, after curation, over 3,000 were still available for the analysis. Overall, 15 genomic regions in the F8 lines had allele frequencies beyond chosen thresholds, indicating selection, eight toward parent Orria and seven toward Plaisant. These selection footprints partially validated QTLs detected through classical linkage mapping in a RIL population of the same cross. These validated selection footprints convey useful information for barley breeding, either through marker-assisted selection or through genomic selection., This work was supported by the Spanish Ministry of Science and Innovation (MICINN), who funded this work with the scholarship BES‐2008‐009623 (EM), and the projects AGL2010‐21929, RTA03‐028‐C4, RTA2006‐00020‐C04 and RTA2009‐00006‐C04, and by grant A06 from the Aragon Government. Genotype by sequencing was funded by DGA ‐ Obra Social La Caixa [grant number GA‐LC‐059‐2011]. WTBT acknowledges funding by the Scottish Government’s Rural and Environment Science and Analytical Services Division.

31 Pags., 4 Tabls., 1 Fig. Available online 15 September 2013. The definitive version is available at: http://link.springer.com/journal/11032, Advances in plant breeding through marker-assisted selection (MAS) are only possible when genes or quantitative trait loci (QTLs) can contribute to the improvement of elite germplasm. A population of recombinant inbred lines (RILs) was developed for one of the best crosses of the Spanish National Barley Breeding Program, between two six-row winter barley cultivars Orria and Plaisant. The objective of this study was to identify favourable QTLs for agronomic traits in this population, which may help to optimise breeding strategies for these and other elite materials for the Mediterranean region. A genetic linkage map was developed for 217 RILs, using 382 single nucleotide polymorphism markers, selected from the barley oligonucleotide pool assay BOPA1 and two genes. A subset of 112 RILs was evaluated for several agronomic traits over a period of 2 years at three locations, Lleida and Zaragoza (Spain) and Fiorenzuola d’Arda (Italy), for a total of five field trials. An important segregation distortion occurred during population development in the region surrounding the VrnH1 locus. A QTL for grain yield and length of growth cycle was also found at this locus, apparently linked to a differential response of the VrnH1 alleles to temperature. A total of 33 QTLs was detected, most of them for important breeding targets such as plant height and thousand-grain weight. QTL × environment interactions were prevalent for most of the QTLs detected, although most interactions were of a quantitative nature. Therefore, QTLs suitable for MAS for most traits were identified., This work was supported by the Spanish Ministry of Science and Innovation (MICINN), who funded this work with the scholarship BES-2008-009623 (EM), and the projects AGL2010-21929, GEN2006-28560- E and RTA2009-00006-C04. The James Hutton Institute receives grant in aid from the Scottish Government's Rural and Environment Science and Analytical Services Division.

11 Pags., 7 Tabls., 1 Fig., The Spanish Barley Breeding Program is carried out by four public research organizations, located at the most representative barley growing regions of Spain. The aim of this study is to evaluate the program retrospectively, attending to: i) the progress achieved in grain yield, and ii) the extent and impact of genotype-by-environment interaction of grain yield. Grain yields and flowering dates of 349 advanced lines in generations F8, F9 and F10, plus checks, tested at 163 trials over 11 years were analized. The locations are in the provinces of Albacete, Lleida, Valladolid and Zaragoza. The data are highly unbalanced because the lines stayed at the program for a maximum of three years. Progress was estimated using relative grain yield and mixed models (REML) to homogenize the results among years and locations. There was evident progress in the program over the period studied, with increasing relative yields in each generation, and with advanced lines surpassing the checks in the last two generations, although the rate of progress was uneven across locations. The genetic gain was greater from F8 to F9 than from F9 to F10. The largest non-purely environmental component of variance was genotype-by-location-by-year, meaning that the genotype-by-location pattern was highly unpredictable. The relationship between yield and flowering time overall was weak in the locations under study at this advanced stage of the program. The program can be continued with the same structure, although measures should be taken to explore the causes of slower progress at certain locations., This scientific work was supported by the Spanish Ministry of Science and Innovation (MICINN) for funding this work with the scholarship BES-2008- 009623 (EM) and the project AGL2007-63625. The Spanish National Barley Breeding Programme has been financed by successive grants from the Spanish Ministry of Science and Innovation (MICINN), the last one being the project RTA2009-00006-C04.