Growth Of Durum Wheat Research Articles

Potential subterranean interference of Solanum elaeagnifolium, commonly known as silverleaf nightshade, on durum wheat

Aim of study: Silverleaf nightshade (Solanum elaeagnifolium) has evolved as an invasive weed in Greece, affecting many farmers’ fields. The potential subterranean interference of silverleaf nightshade on durum wheat growth and yield, as well as its aqueous extracts phytotoxic activity on four winter cereals were investigated. Area of study: Northern Greece. Material and methods: The phytotoxic activity of silverleaf nightshade was determined in the laboratory using a perlite-based bioassay. The interference of silverleaf nightshade on durum wheat yield components was investigated by a 3-year field experiment. Main results: The silverleaf nightshade leaves/stems or the flowers/fruits extracts were in most cases more phytotoxic than those of roots. Durum wheat and oats were more sensitive than winter wheat and barley. In the field, the incorporated summer biomass of 14-18 plants m-2 (about 4.5-4.8 t ha-1) of silver nightshade caused 14.5, 23.1, 23.3, 15.9, 17.3 and 16.9% reduction (averaged across years) in durum wheat plant number, tiller number, total fresh weight, total dry weight, ear number and seed yield, respectively, compared with the silver nightshade-free plots (control). The corresponding reductions caused by 30-34 plants m-2 (about 8.3-8.6 t ha-1) were 28.5, 41.2, 45.9, 31.5, 27.0 and 31.2%. Research highlights: The presence of aboveground silver nightshade biomass, incorporated by tillage before seeding significantly reduced the emergence, growth and yield of durum wheat. This fact could be attributed to the allelopathic effect of the weed and demonstrates the need for its control before wheat establishment to enhance wheat productivity.

Evaluation of the suitability of biological and chemical seed dressing formulations for the protection of durum wheat against the pathogen causing sharp eyespot

The aim of this study, conducted in 2020–2023, was to analyze the incidence of sharp eyespot on the stem bases of durum wheat in two Polish regions, and to evaluate the effectiveness of chemical and biological seed treatments in reducing seedling infection by Rhizoctonia cerealis in vitro and in vivo. During the four-year experiment, sharp eyespot was sporadically observed on several durum wheat cultivars only in north-eastern Poland. Seed dressing products containing triticonazole and prochloraz as a copper complex (KintoDuo 080 FS), fludioxonil (Omnix 025 FS), prothioconazole, tebuconazole, and fluoxastrobin (Scenic 080 FS), and yeast strains reducedR. cerealis colony growth in vitro. All tested chemical and biological seed dressing formulations reduced seedling infection by R. cerealis, andScenic 080 FS was most effective. The formulations containing triazoles as active substances inhibited the growth of durum wheat seed¬lings. In contrast, seed treatment with a suspension of selected strains of Rhodotorula glutinis 418 and Debaryomyces hansenii J1 yeasts significantly stimulated seedling growth, compared with control seedlings.

Fusarium foot rot: Monitoring and characterization of soil-rhizosphere populations in durum wheat

A complex of Fusarium species is commonly isolated from soil rhizosphere of durum wheat plants affected by Fusarium foot rot (FFR), but information on their distribution and relative abundance as well as their role in the pathogenic process has yet to be clarified. To this end, two aspects were analyzed in our investigation. On the one hand we examined Fusarium populations from soil rhizosphere of affected durum wheat plants harvested at tillering growth phase (29 BBCH - scale) in 8 cereal farms (sites A-H) in the most representative areas of durum wheat production in Sicily. Regarding this first aspect, 17 Fusarium species were identified based on their morphological characteristics and molecular traits. F. acuminatum, F. compactum, F. equiseti, F. oxysporum, and F. solani were isolated from soil rhizosphere samples of all sites and their inoculum densities averaged 483, 864, 649, 1629 and 1543 colony forming units per gram of soil (CFU/g-1), respectively. F. culmorum (1158 CFUs) was found in 7 of the 8 sites. The other Fusarium species were isolated from 5 (F. lateritium and F. semitectumi), 4 (F. merismoides), 2 (F. avenaceum and F. sporotrichioides) and 1 (F. crookwellense, F. dimerum, F. graminearum, F. verticillioides, F. subglutinans and Microdochium nivale) of the 8 cereal sites respectively. On the other hand, 30 pure cultures of the most frequent Fusarium spp. (Fusarium acuminatum, F. compactum, F. equiseti and F. culmorum), chosen to represent all four species of each of the sites, were assayed in vitro to evaluate their effect on seed germination and seedling development. In comparison to the (uninoculated) control, F. acuminatum significantly decreased seed germination, shoot height, root length and vegetative vigour by 80.2, 79.6, 90.8 and 97.4 % respectively. F. culmorum showed the greatest inhibition of all vegetative parameters. F. compactum and F. equiseti resulted in increased, albeit not statistically significant, seed germination. Moreover, F. compactum significantly increased root length (+ 39.0 %) and vegetative vigour (+ 17.0 %), while F. equiseti improved both coleoptile growth (+ 34.0 %) and vegetative vigour (+ 18.0 %). These results corroborate the pathogenicity of F. acuminatum and F. culmorum identified in this study, in terms of reduced seed germination and seedling growth of durum wheat. On the contrary, F. compactum and F. equiseti seem uninfluential on seed germination. In particular, F. equiseti increased shoot growth while both species (F. compactum and F. equiseti) increased root development and vegetative vigour, prompting speculation as to actual role of these two species in the soil rhizosphere of durum wheat plants affected by FFR complex.

Control of Resistant False Cleavers (Galium spurium L.) Population to ALS-Inhibiting Herbicides and Its Impact on the Growth and Yield of Durum Wheat

False cleavers (Galium spurium L.) is an annual broadleaf weed, commonly found in cereal crops around the world. It reduces crop yields mainly by the competition for nutrients and plant lodging, which decreases the photosynthetic rate of cultivated plants. Two field experiments were carried out in different locations to examine the efficacy of post-emergence herbicides against false cleavers in durum wheat (Triticum durum Desf.). Herbicides that belong to sulfonylureas, triazolopyrimidines, and other groups (e.g., nitriles and synthetic auxins) were applied. The results revealed that the herbicide florasulam + aminopyralid provided low efficacy (57%) against this weed species, while the most effective herbicides were bromoxynil + 2,4-D and halauxifen-methyl + florasulam. Bromoxynil + 2,4-D efficacy against false cleavers was 73% and 97% at Domokos and Velestino, respectively, while halauxifen-methyl + florasulam efficacy ranged between 89% and 97%. Moreover, the herbicides metsulfuron-methyl + bensulfuron-methyl and pyroxsulam/florasulam + 2,4-D provided low efficacy (<11%) against false cleavers, revealing resistance to ALS-inhibiting herbicides. Regarding the impact of false cleavers and other weed species on the growth of durum wheat, the results showed that the greatest dry biomass (8508.3–8922.7 kg ha−1 and 13,041.4–13,523 kg ha−1 at Domokos and Velestino, respectively) was found in the bromoxynil + 2,4-D, halauxifen-methyl + florasulam, and weed-free treatments. Similar results were also recorded for 1000-seed weights and crop yields, while there were no statistically significant differences among the treatments for spike length. Finally, our results revealed that the herbicides bromoxynil + 2,4-D and halauxifen-methyl + florasulam effectively controlled the resistant false cleavers population. However, it is important to note that halauxifen-methyl + florasulam was recently registered in Greece and other countries and, thus, should be used sensibly by farmers in a rotation with other herbicides to prevent the development of resistant populations.

Comparative effectiveness of exogenous organic amendments on soil fertility, growth, photosynthesis and heavy metal accumulation in cereal crops

With soil fertility loss reached a critical state in arid and semi-arid regions, farmers are constrained to use mineral fertilizers, which are costly, non-eco-friendly and less effective in improving soil fertility than organic fertilizers such as dewatered sewage sludge (SS) and poultry manure (PM). In this regard, the current study aimed to highlight through experiments the positive effect of SS and PM applications on soil fertility and durum wheat growth. It targeted to demonstrate the safe and wise use of organic fertilization while assessing heavy metals in both soil and plant. The experiment was carried out in two batches of thirty-two pots, one for each treatment (SS and PM), in addition to the control with no fertilization. SS and PM were applied separately in three doses (D1 = 50 g, D2 = 100 g, and D3 = 200 g DM fertilizer/pot). The applications of both SS and PM induced a significant increase in plant-available phosphorus, organic matter, nitrates, moisture and electrical conductivity in soil, where these improvements were higher in PM compared to SS treatment. A significant accumulation of proline associated with an increase in biomass that were both proportional with fertilizer dose levels. Our findings revealed a loss in relative water content and leaf area of the plant. Correlations showed several significant relationships between soil parameters studied. The dose D2 of each fertilizer was the most efficient to improving both soil properties and plant components. Plant zinc concentration increased significantly with increase in soil zinc in PM amendments, however it decreased in SS. These relationships were not significant in copper for the two fertilizers. Both SS and PM improved soil fertility and plant growth compared to the control, thus this practice is a promising solution to tackle soil fertility loss and low production in drylands.

Durum Wheat Production as Affected by Soil Tillage and Fertilization Management in a Mediterranean Environment

Several strategies have been proposed recently to reduce the accumulated harmful circumstances of intensive conventional farming practices. The adoption of conservation soil tillage and organic fertilization techniques could contribute to achieving this goal. The study was conducted over a three-year trial to assess the effects of soil tillage practices (plough; subsoil; spading) and fertilization management (inorganic vs. organic) on durum wheat growth dynamics and productivity in a Mediterranean environment. The chlorophyll concentration (CC) was evaluated using an MC-100 chlorophyll meter, and Green Area (GA) was extracted from red-green-blue (RGB) digital images acquired with a commercially available digital camera. These non-destructive low-cost methods were used to examine crop status and its reactions to climate conditions over three consecutive growing seasons in the field. A positive strong linear relationship between both CC and GA against grain yield in each growing season was identified. The study highlights that CC and GA methods are valuable tools to assess crop development under Mediterranean conditions. The results indicated that the applied conservation tillage systems, such as subsoil tillage and using the spading machine, along with organic fertilization with compost, are valuable choices in the Mediterranean basin for sustainable and higher crop production (13%) compared to the conventional traditional system.

Nitrogen Availability Drives Mycorrhizal Effects on Wheat Growth, Nitrogen Uptake and Recovery under Salt Stress

The arbuscular mycorrhizal (AM) symbiosis is generally considered effective in improving salt tolerance in plants; however, the advantages it offers can vary greatly depending on the context in which it occurs; furthermore, the mechanisms underlying these responses are still unclear. A study was conducted to investigate the role of nitrogen (N) availability on the effectiveness of AM symbiosis in durum wheat (Triticum durum Desf.) plants grown under salt stress. Plants were grown in pots in the absence or in presence of salt stress (soil electrical conductivity of 1.50 and 13.00 dS m−1, respectively), with or without AM fungi inoculation (Rhizophagus irregularis and Funneliformis mosseae), varying the N dose supplied (0 or 80 mg N per pot). Results indicate that AM symbiosis can alleviate the detrimental effects of salt stress on the growth of durum wheat only when plants are grown under sufficient N availability in soil; in such conditions mycorrhizal symbiosis determined an improvement of leaf traits (leaf area, SLA, stability of plasma membranes and SPAD), N uptake, N fertilizer recovery and water use efficiency. On the contrary, when wheat plants were grown in conditions of N deficiency, the mycorrhizal symbiosis had no effect (under salt stress) or even depressive effect (under unstressed condition) on plant growth and N uptake, highlighting how, in some cases, competition for nutrients between plants and AM can arise. This study suggests that N availability in the soil can drive the effects of AM symbiosis in assisting the plant with containing saline stress.

Semi-Arid-Habitat-Adapted Plant-Growth-Promoting Rhizobacteria Allows Efficient Wheat Growth Promotion

Plant-growth-promoting rhizobacteria (PGPR) introduced into agricultural ecosystems positively affect agricultural production and constitute an ecological method for sustainable agriculture. The present study demonstrated the effects of two PGPR, Pantoea agglomerans strain Pa and Bacillus thuringiensis strain B25, on seed germination, on the plant growth of two durum wheat varieties, Bousselam and Boutaleb, and on the frequency of the cultivable beneficial bacterial community. The bacterial strains were used as seed primers (individually or in consortia) by coating them with carboxymethyl cellulose (CMC 1%). The effect of PGPR was negligible on germinative ability but improved seed vigor in the Boutaleb variety after inoculation with the Pa strain alone or in combination with the B25 strain. The results showed that the germination capacity depends on the wheat variety. It seemed to be better in the Bousselam variety. Analysis of the results of morphological plant parameters in sterile compost after 75 days under controlled conditions (16 h light, 26/16 °C day/night) showed a significant improvement in plant growth in both wheat varieties with the Pa strain alone or in combination. Chlorophyll (a, and total), carotenoid, and total soluble sugars were significantly increased, while proline and MDA were strongly reduced by inoculation of the Bousselam variety. Bacterial survival of the Pa and B25 strains in the rhizosphere of sterile compost was appreciable (105–107 CFU/g) for both the Pa and B25 strains. Only the Pa strain was endophytic and able to colonize roots. Contrary to sterile compost, the different inoculation treatments in natural soil (after 114 days) significantly improved all morphological parameters and chlorophyll pigments in both wheat varieties. The reduction of proline contents at the leaf level was observed with Pa, mainly in Bousselam. Bacterial densities of the rhizosphere and endophyte cultivable communities did not differ significantly. However, the number of cultivable beneficial bacteria isolated from roots and rhizosphere with multiple PGP traits was significantly increased. Bacterial survival of CMC-coated seed inoculum was appreciable and remained constant, especially for the Pa strain, during 21 months at room temperature. Based on these results, the PGPR used after seed priming would be a feasible and sustainable strategy to improve soil fertility and promote growth of durum wheat in stressful and non-stressful environments.

Phytotoxicity effect concentrations (ECx) for Ce, Nd and Eu added to soil relative to total and bioaccessible soil REE concentrations, and tissue REE accumulations

Toxicity thresholds (ECx) for radish, tomato, and durum wheat growth endpoints (shoot length, shoot mass, root length) to Ce, Nd or Eu added to a black organic soil were determined from 14-day dose-response growth assays. EC10 expressed as total soil [REE] had a more than twenty-fold range, from 337 mg/kg to more than >8000 mg/kg. Averaged over all REEs and endpoints, durum wheat was more tolerant than radish and tomato; and averaged over all endpoints, Eu appeared to be the most phytotoxic of the three REEs. Bioaccessibility of each REE was determined by extraction with 0.01 M CaCl2, which for all three REEs in this soil was quite low, <0.10% of total. However, bioaccessibility of Eu was five or six times greater than that for Ce and Nd, and thus could explain its apparently greater toxicity, namely that Eu was more likely to be accumulated at the site of toxic action in the plant. To discern inherent toxicity from enhanced bioaccumulation, concentration of each REE in root and shoot tissues was determined, for a tissue-residue approach to toxicity assessment. The EC10 expressed as tissue concentration was lower for Nd than for Ce and Eu, thus the most toxic of the three REEs. As for many cationic inorganic elements, toxicity varies with the chemistry of the exposure medium due to its effects on bioaccessibility. Simple methods to harmonize toxicity thresholds from different media enables greater integration into regulatory standards. When EC25 from this and other studies were normalized to CaCl2-extractable REE in their respective media, the range in Ce EC25 was reduced from 20-fold to 2.5-fold, and the range for Eu EC25 was reduced from 25-fold to 3-fold. This novel and low-input approach to meta-analysis of toxicity thresholds demonstrates the value of considering soil physico-chemical properties as modifiers of soil REE toxicity.

Polyphosphate application influences morpho-physiological root traits involved in P acquisition and durum wheat growth performance

BackgroundAmong phosphate (P) fertilizers, polyphosphates (PolyPs) have shown promising results in terms of crop yield and plant P nutrition. However, compared to conventional P inputs, very little is known on the impact of PolyPs fertilizers on below- and above-ground plant functional traits involved in P acquisition. This study aims to evaluate agro-physiological responses of durum wheat variety ´Karim´ under different PolyPs applications. Three PolyPs fertilizers (PolyA, PolyB, and PolyC) versus one orthophosphate (OrthoP) were applied at three doses; 30 (D30), 60 (D60), and 90 (D90) kg P/ha under controlled conditions.The PolyPs (especially PolyB and PolyC) application at D60 significantly increased morphophysiological root traits (e.g., RL: 42 and 130%; RSA:40 and 60%), shoot inorganic P (Pi) content (159 and 88%), and root P acquisition efficiency (471 and 296%) under PolyB and PolyC, respectively compared to unfertilized plants. Above-ground physiological parameters, mainly nutrient acquisition, chlorophyll content and chlorophyll fluorescence parameters were also improved under PolyB and PolyA application at D60. A significant and positive correlation between shoot Pi content and rhizosphere soil acid phosphatase activity was observed, which reveal the key role of these enzymes in PolyPs (A and B) use efficiency. Furthermore, increased P uptake/RL ratio along with shoot Pi indicates more efficient P allocation to shoots with less investment in root biomass production under PolyPs (especially A and B).ConclusionsUnder our experimental conditions, these findings report positive impacts of PolyPs on wheat growth performance, particularly on photosynthesis and nutrient acquisition at D60, along with modulation of root morpho-physiological traits likely responsible of P acquisition efficiency.

Effect of endophytic bacteria from Algerian prickly pear roots on wheat under drought stress

Cactus are among the most drought tolerant plants. As Opuntia is able to grow under the stress of drought, this study aims to check if endophytic bacteria isolated from cactus roots have beneficial potential for crops such as wheat during drought. Two endophytic bacterial isolates were isolated from the roots of the cactus and screened for their plant growth promoting characteristics, such as N-free growth and auxin production. These bacteria have demonstrated their potential to promote the growth of durum wheat under in-vitro conditions and have been identified as Pseudomonas putida and P.brassicacearum, following the sequencing of the 16S rRNA gene and phylogenetic analysis, and significantly improved growth parameters such as seeding length compared to the unobstructed control. After 05 days of contact of the two bacteria, P.putida and P.brassicacearum, with sprouted wheat seeds, a root growth rate of (39.88% and 62.14%, respectively) was recorded. The same effect on the growth of wheat roots is caused by the volatile substances of these bacteria deposited separately, with a rate of (53.30% and 24.18%) respectively. Symptoms of drought stress were visibly reduced on seedlings inoculated with P.putida and P.brassicacearum bacteria, a result supported by a growth rate of root parameters in length (260.83% and 179.60%), surface (21.98% and 60.17%) and scope (59.46% and 62.67%), respectively. This work opens up many perspectives for the characterization and selection of endophyte bacteria of under-used drought-tolerant species such as cacti for the improvement of the growth of field crops. These results promote the deployment of Pseudomonas sp as an effective biofertilizer in wheat.

Impacts of Nano-Ferric Oxide on Morpho-Physiological Traits of Durum Wheat

Nanotechnology has shown a promising potential to encourage sustainable agriculture in the recent years. Iron (Fe) is an essential element for plant growth and development which absence in the soil negatively effects the plant health. We proposed that the application of nano-ferric oxide at certain level would promote the overall performance of durum wheat. Thus, in the recent study, we evaluated the two durum wheat genotypes (Preco and Kronos) under three levels of nano-ferric oxide (0 ppm, 20 ppm and 50 ppm). The experiment was conducted in the Botany Laboratory of University of Lahore, Sargodha campus during 2017-2018 with a completely randomized block design. Nano-Ferric oxide particles were synthesized by the chemical reduction of ferric chloride hexahydrate (FeCl3.6H2O) using onion extract. The size of nanoparticles was determined by Zeta Particle Analyzer. The results of the observed traits revealed highly significant differences among treatments and genotypes. The results shown that observed traits improved under 20 ppm concentration of nano-ferric oxide but decreased under 50 ppm concentration. At 20 ppm treatment, variety Preco showed the highest plant height (109.56 cm), root length (19.42 cm), spike length (12.48 cm), awns length (19.83 cm), internode length (19.12 cm), number of leaves (14.55), number of spikelets (23.77), number of awns (55.88), thousand-grain weight (49.49 g), relative water contents (94.81), glaucousness (9.52) and pubescence (8.88). Overall, results suggested that ferric oxide nanoparticles improve the growth of durum wheat and can be used for crops improvement in future.

Biopriming of Durum Wheat Seeds with Endophytic Diazotrophic Bacteria Enhances Tolerance to Fusarium Head Blight and Salinity.

There is growing interest in the use of bio inoculants based on plant growth-promoting bacteria (PGPB) to promote plant growth under biotic and abiotic stresses. Here, we provided a detailed account of the effectiveness of a number of endophytic PGPB strains, isolated from the roots of the halophyte Salicornia brachiata in promoting durum wheat growth and enhancing its tolerance to salinity and fusarium head blight (FHB) disease. Bacillus spp. strains MA9, MA14, MA17, and MA19 were found to have PGPB characteristics as they produced indole-3-acetic acid, siderophores, and lytic enzymes, fixed free atmospheric nitrogen, and solubilized inorganic phosphate in vitro. Additionally, the in vivo study that involved in planta inoculation assays under control and stress conditions indicated that all PGPB strains significantly (p < 0.05) increased the total plant length, dry weight, root area, seed weight, and nitrogen, protein, and mineral contents. Particularly, the MA17 strain showed a superior performance since it was the most efficient in reducing disease incidence in wheat explants by 64.5%, in addition to having the strongest plant growth promotion activity under salt stress. Both in vitro and in vivo assays showed that MA9, MA14, MA17, and MA19 strains were able to play significant PGPB roles. However, biopriming with Bacillus subtilis MA17 offered the highest plant growth promotion and salinity tolerance, and bioprotection against FHB. Hence, it would be worth testing the MA17 strain under field conditions as a step towards its commercial production. Moreover, the strain could be further assessed for its plausible role in bioprotection and growth promotion in other crop plants. Thus, it was believed that the strain has the potential to significantly contribute to wheat production in arid and semi-arid regions, especially the salt-affected Middle Eastern Region, in addition to its potential role in improving wheat production under biotic and abiotic stresses in other parts of the world.

Durum wheat salt stress tolerance is modulated by the interaction between plant genotypes, soil microbial biomass, and enzyme activity

Understanding the relationship between durum wheat genotypes and soil biochemistry under salt stress plays a key role in breeding for yield superior genotypes. Thus, microbial biomass carbon (MBC) and nitrogen (MBN), the activity of three selected enzymes including dehydrogenase (D-ase), alkaline phosphatase (Alk-ase), and protease (P-ase), and available phosphorus (available P) and nitrogen (available N) were assessed. Two landraces and two improved varieties were tested under two salinity levels of water irrigation (0.3 and 12 dS m–1). Soil sampling was carried out at five durum wheat growth stages. The soil biota-genotype interaction seems to affect the biological (MBC, MBN, and enzymatic activities) and chemical (available P and N) traits. The microbial activity of rhizospheric soil was higher at the tillering and flowering stages. Under saline conditions, ‘Maali’ (improved variety) and ‘Agili Glabre’ (landrace) showed the best belowground inputs (e.g., MBC, MBN, enzymatic activities, available P and N) and grain yield (GY) performance. Under the same conditions, four soil biochemical indicators of GY of tolerant genotypes (i.e., ‘Maali’ and ‘Agili Glabre’) were determined as available N, P-ase, available P, Alkase, and D-ase. Stepwise analysis revealed that predictive variables depended on growth stages. Overall, MBC, available N, Alk-ase, and P-ase were the variables that mainly contributed to predicting GY in saline environments. In conclusion, the results suggested a specific interaction between plant genotype roots and soil microbes to overcome salt stress. Thus, soil biological components should acquire more importance in plant salinity tolerance studies. Highlights- Salt-tolerant durum wheat genotypes showed greater microbial activities in the rhizosphere.- Microbial enzymatic changes depended on the interaction plant genotype x soil salinity.- The MBC/MBN ratio and dehydrogenase strongly correlated with grain yield under salinity.- MBC, available N, and alkaline phosphatase as predictors of grain yield at 12 dS m–1.- Tillering and flowering could be key stages of durum wheat salinity tolerance.

Co-inoculation of Trichoderma gamsii A5MH and Trichoderma harzianum Tr906 in wheat suppresses in planta abundance of the crown rot pathogen Fusarium pseudograminearum and impacts the rhizosphere soil fungal microbiome

Wheat root endophytic strains Trichoderma gamsii A5MH and T. harzianum Tr906 were assessed for their abilities to suppress in planta abundance of the crown rot pathogen Fusarium pseudograminearum and increase growth of durum wheat. Fusarium crown rot suppressive assays were conducted in natural Kandosol and Chromosol wheat cropping soils with greater disease expression observed in the Chromosol. Rhizosphere abundance of T. gamsii A5MH, T. harzianum Tr906 and F. pseudograminearum were quantified by species-specific qPCR at plant maturity. Strains A5MH and Tr906 actively colonized the wheat rhizosphere and suppressed in planta pathogen abundance in both soil types, with both inoculants persisting in roots and soil to 84 days postemergence. Strain A5MH increased wheat biomass in both soils, whereas strain Tr906 only increased biomass of Chromosol-grown wheat. Metabolites of strains A5MH and Tr906 decreased in vitro growth of wheat pathogenic F. pseudograminearum, Rhizoctonia solani and Pythium irregulare, but did not inhibit either inoculant. Compared with individually inoculated strains, co-inoculation of A5MH and Tr906 did not affect rhizosphere niche abundance, in planta pathogen suppressive efficacies or wheat growth-benefits of either inoculant in Chromosol-grown wheat. Fusarium crown rot symptoms however, only decreased in the A5MH and co-inoculated treatments. Each Trichoderma treatment had distinct impacts on the structure (beta diversity) of the indigenous rhizosphere soil fungal community of Chromosol-grown wheat. Strain A5MH and co-inoculated treatments had the greatest overall effects on soil fungal community (alpha) diversity and structure. Community differentiation was primarily attributed to increased abundance of Trichoderma spp. in the inoculated treatments and associated decreases in plant pathogenic and predominantly saprophytic fungal genera.

Global loss of climatically suitable areas for durum wheat growth in the future

Durum wheat (Triticum durum Desf.) is a minor cereal crop of key importance for making pasta, couscous, burghul, puddings, bread and many other traditional foods, due to its physical and chemical characteristics. The global demand for high-quality food made of durum wheat has been increasing, which poses a challenge in the face of climate change. Major share of durum wheat production is currently located in semi-arid climates, where the risk of climate extremes such as drought and heat stress will likely substantially increase in the future. To provide a first estimate of future global arable land climatically suitable for growing durum wheat, we develop a suitability model based on support vector machines. The current total share of global arable land climatically suitable to grow rainfed durum wheat is around 13%. Climate change may decrease the suitable area by 19% at mid-century and by 48% at the end of the century. Widespread loss of suitable areas is foreseen in the Mediterranean regions and northern America. On the other hand, climate may become suitable to grow durum wheat in many regions of central and western Europe, while the largest gain in suitability is estimated in some parts of Russia. The overall net loss of suitable areas requires the development and the future adoption of effective and sustainable strategies to stabilize production and adapt the entire food supply chain. Our study also clearly demonstrates the importance of limiting global warming to levels well below 2 °C at the end of the century, which would substantially limit the loss of climatically suitable areas.

Effects of Osmotic Stress Induced by Polyethylene Glycol (Peg) 6000 and Mannitol on Seed Germination and Seedling Growth of Durum Wheat

Seed germination is generally the critical step in seed establishment and thus the determination of successful crop production. This study was focused at examination of the biochemical and germination parameters effected by low water potential which was generated by polyethylene glycol (PEG) 6000 and mannitol, related to drought stress and growth of Waha durum wheat genotype. Two tests were carried out in a growth chamber; the first comprises seed germination into Petri dishes in the presence of different concentrations of the two osmoticums (0, 5, 10, 15 and 20 % of PEG6000 and mannitol). The second test was carried out in nutrient solution BD medium. Our results shows that Both PEG -6000 and mannitol reduced germination. Therefore, a rapid increase was observed in the rate of germination both for the control plants and the plants subjected to a concentration of 5 g/L and 10 g/L and changes in proportion to the time. For the concentration of 15 g/L and 20 g/L, this phase is very short, which explains the reduced germination rate due to the inhibitory effect of the two osmoticums on germination. In this study, PEG-6000 treatments resulted in an increase of some proteins and a decrease of others. Waha displayed 12 bands for control plants, 40 bands for PEG-6000 stressed plants (all treatments) and 35 bands for mannitol treatments.

Chitosan-Induced Activation of the Antioxidant Defense System Counteracts the Adverse Effects of Salinity in Durum Wheat.

The present study was carried out with the aim of (i) evaluating the effect of chitosan (CTS) on the growth of durum wheat under salinity and (ii) examining CTS-regulated mechanisms of salinity tolerance associated with the antioxidant defense system. To achieve these goals, durum wheat seedlings were treated with CTS at different molecular weight, low (L-CTS, 50–190 kDa), medium (M-CTS, 190–310 kDa) and high (H-CTS, 310–375 kDa). The results obtained show that exposure to 200 mM NaCl reduced the shoot and the root dried biomass by 38% and 59%, respectively. The growth impairment induced by salinity was strongly correlated with an increase in the superoxide anion production (5-fold), hydrogen peroxide content (2-fold) and malondialdehyde (MDA) content (4-fold). Seedlings responded to the oxidative stress triggered by salinity with an increase in the total phenolic content (TPC), total flavonoid content (TFC) and total antioxidant activity (TAA) by 67%, 51% and 32%, respectively. A salt-induced increase in the activity of the antioxidant enzymes superoxide dismutase and catalase (CAT) of 89% and 86%, respectively, was also observed. Treatment of salt-stressed seedlings with exogenous CTS significantly promoted seedling growth, with the strongest effects observed for L-CTS and M-CTS, which increased the shoot biomass of stressed seedlings by 32% and 44%, respectively, whereas the root dried biomass increased by 87% and 64%, respectively. L-CTS and M-CTS treatments also decreased the superoxide anion production (57% and 59%, respectively), the hydrogen peroxide content (35% and 38%, respectively) and the MDA content (48% and 56%, respectively) and increased the TPC (23% and 14%, respectively), the TFC (19% and 10%, respectively), the TAA (up to 10% and 7%, respectively) and the CAT activity (29% and 20%, respectively). Overall, our findings indicate that CTS exerts its protective role against the oxidative damages induced by salinity by enhancing the antioxidant defense system. L-CTS and M-CTS were the most effective in alleviating the adverse effect of NaCl, thus demonstrating that the CTS action is strictly related to its molecular weight.

Short-Term Effects of Biosolid Application on Two Mediterranean Agricultural Soils and Durum Wheat Yield

This study evaluated the effects of de-inking paper sludge (DPS) and sewage sludge (SS) application on soil properties, and durum wheat growth and yield. A pot experiment was performed on Calcaric cambisol (clCM) and Cromic Luvisol (coLV) soils. Three DPS rates (0, 30, and 60 Mg ha−1) were studied with and without nitrogen fertilizer (280 kg NH4NO3 ha−1). DPS was also mixed with SS at two rates (5 and 10 Mg ha−1) to highlight the benefits of organic nitrogen compared to mineral nitrogen. DPS improved total organic carbon and nitrogen, mineral nitrogen, and soils cation exchange capacity, the 30% rate provided the greatest improvement in both soils. DPS increased grain and root P, K, Ca, and Mg contents in both soils. It also increased wheat straw N, P, Mg, and Ca for the same soil compared to the control. Mixed DPS treatments with nitrogen fertilizer enhanced grain yield by up to 38% and increased root biomass in the studied soils. Thus, DPS is a potential source of organic matter and a liming agent for acid soils when appropriate supplemental fertilizer is provided.

Effects of intercropping on field-scale phosphorus acquisition processes in a calcareous soil

Calcium uptake by plants and the ratio of calcium to phosphorus (Ca/P) in the uptake have been recently identified as important drivers of P acquisition in neutral to alkaline soils. However, this has rarely been studied under field conditions and no data are available for the effects of intercropping. Durum wheat and faba beans were cultivated, both as sole crops and as intercrops, in a P-deficient, calcareous soil over three consecutive growing seasons. We measured a range of plant, soil, and rhizosphere properties at the flowering stage and grain yield at harvest. Root dry weight, N fixation, rhizosphere acidification, the ratio of Ca/P in the uptake, and available P in the soil were all higher for faba beans intercropped with durum wheat. However, its growth was limited by other factors, probably including water availability. However, durum wheat growth and nutrient acquisition were markedly facilitated by intercropping with faba beans. The facilitation of P acquisition by durum wheat was caused by the acidification of its rhizosphere, the subsequently higher solubility of Ca-P minerals, and the lack of competition by faba beans for P. The results confirm the importance of Ca uptake and the ratio of Ca/P in the uptake for P acquisition by plants in calcareous soils and, more specifically, for a cereal intercropped with faba beans.