A Combination of Leaf Rust Resistance Genes, Including Lr34 and Lr46, Is the Key to the Durable Resistance of the Canadian Wheat Cultivar, Carberry

The hexaploid spring wheat cultivar, Carberry, was registered in Canada in 2009, and has since been grown over an extensive area on the Canadian Prairies. Carberry has maintained a very high level of leaf rust (Puccinia triticina Eriks.) resistance since its release. To understand the genetic basis of Carberry’s leaf rust resistance, Carberry was crossed with the susceptible cultivar, Thatcher, and a doubled haploid (DH) population of 297 lines was generated. The DH population was evaluated for leaf rust in seven field environments at the adult plant stage. Seedling and adult plant resistance (APR) to multiple virulence phenotypes of P. triticina was evaluated on the parents and the progeny population in controlled greenhouse studies. The population was genotyped with the wheat 90 K iSelect single nucleotide polymorphism (SNP) array, and quantitative trait loci (QTL) analysis was performed. The analysis using field leaf rust response indicated that Carberry contributed nine QTL located on chromosomes 1B, 2B (2 loci), 2D, 4A, 4B, 5A, 5B, and 7D. The QTL located on 1B, 2B, 5B, and 7D chromosomes were observed in two or more environments, whereas the remainder were detected in single environments. The resistance on 1B, detected in five environments, was attributed to Lr46 and on 7D, detected in seven environments to Lr34. The first 2B QTL corresponded with the adult plant gene, Lr13, while the second QTL corresponded with Lr16. The seedling analysis showed that Carberry carries Lr2a, Lr16, and Lr23. Five epistatic effects were identified in the population, with synergistic interactions being observed for Lr34 with Lr46, Lr16, and Lr2a. The durable rust resistance of Carberry is attributed to Lr34 and Lr46 in combination with these other resistance genes, because the resistance has remained effective even though the P. triticina population has evolved virulent to Lr2a, Lr13, Lr16, and Lr23.

Combination of yeast antagonists and Acibenzolar-S-Methyl reduced the severity of Fusarium head blight of wheat incited by Fusarium graminearum sensu stricto

The combination of yeast antagonists and Acibenzolar-S-Methyl (ASM) was tested against Fusarium graminearum on a spring wheat cultivar PAN3471. Two strains of Papiliotrema flavescens (Strains WL3 and WL6) and a strain of Pseudozyma sp. (MGO1) were combined with full strength ASM at anthesis, half strength ASM at anthesis and quarter strength ASM at late boot stages. The yeast and ASM treatments were applied prior to F. graminearum inoculation and disease progress was assessed over time. The combination of yeast and ASM treatments effectively reduced Fusarium Head Blight (FHB) severity and deoxynivalenol (DON) concentration compared to when the treatments were used alone. A positive correlation was observed between the Area Under Disease Progress Curve (AUDPC) and Percentage Seed Infection (PSI) (r = 0.44) whereas a negative correlation was observed between AUDPC and Hundred Seed Weight (HSW) (r = -0.77) and PSI and HSW (r = -0.44). The best combination treatment providing the highest reduction in final disease severity (41.83%), high HSW and moderate PSI was 0.075 g/l ASM at anthesis plus P. flavescens strain WL3. The highest DON reduction (19.35%) was by the treatment 0.075 g/l ASM at anthesis plus P. flavescens strain WL6. The best treatment was P. flavescens combined with 0.075 g/l ASM at anthesis. Although Pseudozyma sp. strain MGO1 did not provide the best FHB and DON reduction, its combination with ASM application improved disease control efficacy. To the best of our knowledge, this study presents the first report of the combination of P. flavescens and ASM in the management of FHB caused by F. graminearum in wheat plants.

Water Stress Affects the Some Morpho-Physiological Traits of Twenty Wheat (Triticum aestivum L.) Genotypes under Field Condition

Water stress has become one of the foremost constraints to agricultural development, mostly in areas that are deficient in water. A field trial has been conducted to evaluate the performance of different twenty wheat genotypes under three stress treatments viz., control (T0) = normal watering, stress-1 (T1) = water stress from tillering up to maturity, and stress-2 (T2) = water stress from anthesis to maturity were used as treatments. The results revealed that a highly significant (p < 0.01) difference was observed among twenty wheat cultivars for morpho-physiological traits except for several tillers plant−1, spikeletspike−1, and relative water content. In the early days, 50% flowering was noted in Anmole-91 (64.33 days) under (T0), while Anmol-91 showed a relative decrease (RD-1) (−2.34 days) at days 50% flowering in (T1). The TJ-83 genotype showed an early response (−8.34 day) at days to 50% flowering under stress-2 (T2), but TD-I (−3.34) was observed to be relatively tolerant. Underwater stress from tillering to maturity (T1) SKD-1 was found more susceptible (−36.7 days) than other cultivars. Wheat cultivar Soghat-90 showed maximum RD-1 (−24.7) for grain yield plant−1 in stress-1 (T1) from tillering to maturity. Anmole-91, NIA-Sarang, and TD-I observed minimum was (−6) in the same water stress for various traits. Therefore, the findings of present work revealed that the best performing genotypes can be recommended for effective cultivation in future breeding programs.

Identification and Mapping of QTL for Stripe Rust Resistance in the Chinese Wheat Cultivar Shumai126

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is a damaging disease of wheat globally, and breeding resistant cultivars is the best control strategy. The Chinese winter wheat cultivar Shumai126 (SM126) exhibited strong resistance to P. striiformis f. sp. tritici in the field for more than ten years. The objective of this study was to identify and map quantitative trait loci (QTL) for resistance to stripe rust in a population of 154 recombinant inbred lines (RILs) derived from a cross between cultivars Taichang29 (TC29) and SM126. The RILs were tested in six field environments with a mixture of the Chinese prevalent races (CYR32, CYR33, CYR34, Zhong4, and HY46) of P. striiformis f. sp. tritici and in growth chamber with race CYR34 and genotyped using the Wheat55K SNP (single nucleotide polymorphism) array. Six QTL were mapped on chromosomes 1BL, 2AS, 2AL, 6AS, 6BS, and 7BL, respectively. All these QTL were contributed by SM126 except QYr.sicau-2AL. The QYr.sicau-1BL and QYr.sicau-2AS had major effects, explaining 27.00-39.91% and 11.89-17.11% of phenotypic variances, which may correspond to known resistance genes Yr29 and Yr69, respectively. The QYr.sicau-2AL, QYr.sicau-6AS, and QYr.sicau-6BS with minor effects are likely novel. QYr.sicau-7BL was only detected based on growth chamber seedling data. Additive effects were detected for the combination of QYr.sicau-1BL, QYr.sicau-2AS, and QYr.sicau-2AL. SNP markers linked to QYr.sicau-1BL (AX-111056129 and AX-108839316) and QYr.sicau-2AS (AX-111557864 and AX-110433540) were converted to breeder-friendly KASP (Kompetitive allele-specific PCR) markers that would facilitate the deployment of stripe rust resistance genes in wheat breeding.

Adoption of Durum Wheat Cultivar ‘Salim’ with a Technical Package and Its Resilience to Climate Change Impacts in Smallholders: Case of Nebeur/Kef Region, Tunisia

In recent years, there has been an urgent need for local strategies to ensure food sustainability in Tunisia, recognized as a climate change hotspot region. In this context, adaptation measures, including the adoption of high-yielding durum wheat cultivars with adequate agronomical practices, are an important avenue to improving the productivity of the smallholders that represent 80% of Tunisian farmers. Thus, this study highlights the impact of (i) the adoption of the recently marketed durum wheat cultivar ‘Salim’ as compared to the common cultivar ‘Karim’ and the transfer of a technical package to 11 farmers in the Nebeur delegation/Kef-Tunisia (semi-arid region) during the 2013/2014 and 2014/2015 cropping seasons, and (ii) climate change on the expected mean grain yield and biomass by 2070, using the CropSyst agronomic cultivation model based on multi-year crop simulations run with a daily weather series (2020–2070). The adoption of ‘Salim’ with the recommended package, compared to ‘Karim’ with the farmer practices, significantly increased the grain yield (37.84%) and biomass (55.43%). Otherwise, the impact of the 0.8 °C temperature rise on the potential yields and biomass over the next 51 years was positive. Contrary to expectations, the yield increases for the two cultivars were very close, but the yield of ‘Salim’ (36.02 q ha−1) remains much higher than that of ‘Karim’ (23.34 q ha−1). On other hand, ‘Salim’ experienced a higher increase for biomass compared to that of ‘Karim’. These results indicate that the adoption of the ‘Salim’ cultivar with its technical package might be considered as a strategy of adaptation to Nebeur conditions and to future climate change events.

Development of wheat plants coinoculated with rhizobium strains

ABSTRACT This study aimed to evaluate the efficiency of diaztrophic bacteria coinoculation in wheat cultivars grown in Cerrado Oxisol. A randomized block design was used, with a 13 x 3 factorial scheme and four replicates. The treatments consisted of inoculation with Azospirillum brasilense (strains AbV5 and AbV6 strains combined) and coinoculation with Bradyrhizobium japonicum (strains SEMIA 5079 and SEMIA 5080 combined, and strain BR3267), as well as Rhizobium tropici (strains MT08 and MT15) and R. leguminosarum (strain MT16) combined or in isolation, tested in wheat cultivars BRS 394, BRS 264 and BRS 254. The variables analyzed were grain nitrogen concentration and accumulation and crude protein content, 100-grain weight and total grain mass. The treatment containing the commercial cowpea inoculant showed a higher total grain mass (5.8766 g). Interaction was observed for grain nitrogen concentration, particularly for A. brasilense + MT 15 (R. tropici) and MT 15 in wheat cultivar BRS 264. Coinoculation with diazotrophic bacteria isolated from leguminous plants shows potential for use in wheat cultivars.

Effect of Some Planting Depths on Wheat Characteristics for Two Varieties (Iba'a 99 and Alnoor)

The impact of sowing depth in planting machine (Nordsten type) on wheat varieties (VW-Iba’a 99 and VW-Alnoor ) were tested during planting machine at three sowing depths of SD-5.4, 7, and 8.6 cm. The experiments were conducted in a factorial experiment under a complete randomized design with three replications. The wheat cultivar (VW-Iba’a 99) was meaningfully better than (VW-Alnoor ) in all studied parameters. For (VW-Iba’a 99), the germination ratio, length plant, plant vigor index, root length, root fresh weight, root plant dry, and grain yield, were 90.369%, 68.04cm, 57.14%, 17.09 cm, 1.42 g, 0.54g, and 4.441 tha-1, respectively. The sowing depth (SD -5.4cm) was significantly better than (SD-7 and 8.6cm ) in all studied parameters. The greatest assessments have come from the overlap among the SD -5.4cm, and VW_Iba’a 99.

Cultivar Grain Yield in Durum Wheat-Grain Legume Intercrops Could Be Estimated From Sole Crop Yields and Interspecific Interaction Index

Ensuring food security for a world population projected to reach over nine billion by 2050 while mitigating the environmental impacts and climate change represent the major agricultural challenges. Diversification of the cropping systems using notably cereal–legume mixtures is one key pathway for such agroecological intensification. Indeed, intercropping is recognised as a practice having the potential to increase and stabilise the yields in comparison with sole crops while limiting the use of inputs notably when species exploit resources in a complementary way. However, predicting intercropped species grain yield remains a challenge because the species respond to competition through complex genotype x cropping mode interactions. Here, we hypothesised that the grain yield achieved by a cultivar in low nitrogen input durum wheat–grain legume intercrops (ICs) could be estimated using a few simple variables. The present work is based on a 2-year field experiment carried out in southwestern France using two durum wheat (Triticum turgidum L.), four winter pea (Pisum sativum L.), and four winter faba bean (Vicia faba L.) genotypes with contrasting characteristics, notably in terms of height and precocity, to explore a wide range of durum wheat–grain legume phenotypes combinations to generate variability in terms of yield and species proportion. The major result is that the yield of durum wheat–grain legume IC component in low nitrogen input conditions could be correctly estimated from only three variables: (i) wheat cultivar full density sole crop (SC) yield, (ii) legume cultivar half density sole crop (SC½) yield, and (iii) an indicator of legume cultivar response to interspecific competition. The latter variable, the interspecific interaction index (IE), reveals cultivars' competitive abilities and tolerance to competition. However, to propose generic IC design and management procedures, further mechanistic understanding is required to better understand the links between tolerance to interspecific competition and cultivar phenotype characteristics. In particular, a special emphasis on the grain legume is needed as their response to interspecific competition appears less predictable than that of durum wheat. Cultivar choice is a key element to optimise the functional complementarity and subsequent IC advantages. This work proposes a simple tool to assist the design of specific breeding programs for cultivars ideotypes adapted to intercropping.