Yield Gain Research Articles

Convenient Access to a N,N’‐bis(2,6‐terphenyl) Substituted N‐Heterocyclic Carbene

AbstractThe efficient synthesis of a N,N’‐bis(2,6‐terphenyl) substituted N‐heterocyclic carbene (NHC) is reported. The gain in efficiency and total yield, compared to traditional synthesis, is the result of a high yielding and scalable double Suzuki coupling step, affording a 2,6‐terphenyl aniline, catalyzed by a Pd β‐diketiminate complex. A stereoelectronic study revealed the new NHC to be very similar to the only other N,N’‐bis(2,6‐terphenyl) substituted NHC. Application to the stabilization of Group 13 trihydrides gives acceptable outcomes but inferior to those observed when the bulky IPr* NHC is deployed.

Exploring the Role of Farmer-Led Jumpstarting Project on Adoption of Orange-Fleshed Sweet Potato in Nigeria: Implications on Productivity and Poverty

To promote the adoption of the orange-fleshed sweet potato (OFSP) among the farmers, OFSP was introduced to the farmers through a program tagged “Jumpstarting Project” (JP), a West African project initiative of Harvestplus and its partners, which was implemented in Osun and Kwara States, in Nigeria. Using household-level data in Nigeria, this paper examined how the intervention of a farmer-led multiplication–dissemination Jumpstarting Project has sustained the adoption of OFSP after years of its implementation and the consequent impact of adoption on productivity and welfare of the farmers. Our main empirical findings are as follows. First, the implementation of the Jumpstarting Project in project communities of Osun and Kwara States shows that the adoption of OFSP has increased and has been sustained over the years. Furthermore, the result of the propensity score matching confirms possible spillover between project communities and control groups. Second, estimation from the endogenous treatment effect indicates that the estimated average treatment effects on the treated indicates a yield gain for the adopters of OFSP. Third, the result of the average treatment effects on the treated from the endogenous switching probit model shows that the probability of being poor in the households that adopted OFSP would be 5.3% more if these households did not adopt OFSP. Our results suggest that immediate replication and scaling up of the Jumpstarting Project in other states in Nigeria should be implemented. This study demonstrates that to ensure the diffusion and adoption of improved technologies such as OFSP, intervention projects that promote the adoption of these technologies have a greater role to play.

Assessment of dry matter yield, nutritional value, and calf weight gain in Mombaza-Kudzu pasture associations.

O Objective: To evaluate the biomass production, nutritional value and animal production of an association with fabaceae species and grasses with grazing calves. Design/Methodology/Approach: The study compared Mombaza (Megathyrsus maximus) – Kudzu (Pueraria phaseoloides) association pasture against a Mombaza in monoculture control. Ten calves, five in each pasture type, were grazed in rotation for seven months. Dry matter yield, proportion of Kudzu in the association, protein, neutral detergent fiber (NDF), acid detergent fiber (ADF), ash, and daily weight gain were evaluated every 36 days. Results: Dry matter yield did not differ between pasture types, but varied by sampling dates, being higher at the onset of the rainy season (May 20th). The proportion of Kudzu in the association was low, decreasing from 8.42% to 1.71% over the study period. Lignin content increased in the association during the driest month (April). Daily weight gain was 978 g in the monoculture pasture and 678 g/day in the association, with no significant difference. Study Limitations/Implications: The low persistence of the fabaceae in the association limits the nutritional value of the pasture, consequently, the improvement of grazing animal production. Findings/Conclusions: During the drought season, both pastures exhibited the highest protein concentration and the greatest weight gain at the beginning of this period. However, the association did not result in greater weight gains due to the low persistence of the fabaceae.

The CIMMYT Australia ICARDA Germplasm Evaluation concept: a model for international cooperation and impact.

Bread wheat germplasm is accessed from the International Maize and Wheat Improvement Centre (CIMMYT) and the International Centre for Agricultural Research in the Dry Areas (ICARDA) by Australian wheat breeders and researchers through the CIMMYT Australia ICARDA Germplasm Evaluation (CAIGE) program. The CAIGE program coordinates the selection, importation, quarantine, dissemination, and evaluation of the imported bread wheat germplasm and the management of associated data and information. This paper describes the CAIGE model and assesses both the genetic and economic impacts of these materials on the Australian wheat industry after commercialisation of wheat breeding in the early 21st century and the establishment of CAIGE. The CAIGE concept was validated using data collected and analysed from multi-environment trials between 2017 and 2020. The impact of cultivars with and without CAIGE contribution to pedigree on yield was estimated using production-by-variety statistics. Net gain in yield, estimated as the yield difference between CAIGE and Non-CAIGE varieties, was multiplied by the percentage contribution to pedigree to estimate the additional yield. The CAIGE bread wheat program identified diverse, high-yielding, and disease-resistant germplasm and significantly improved the capture and dissemination of information. The benefit-cost ratio, calculated as the sum of benefits divided by investments, indicated that, for every dollar invested in CAIGE, a further $20 was generated in benefits. The internal rate of return was estimated at 163% and the modified rate at 18%. The benefits of these international materials to Australian wheat breeding remained significant.

Maize breeding effects on grain yield genetic progress and its contribution to global yield gain in Argentina

Context or problemMaize production in Argentina has increased in recent years, following the global gain (GG) in grain yield (GY). The GG in GY depends on genetic progress (GP), which requires frequent quantification to detect potential plateaus and variations in its contribution to the GG. In this sense, hybrid adoption in Argentina shifted from double- and three-way to single cross (F1) hybrids in the 1990s, thereby increasing the level of heterosis of released hybrids. Since heterosis increase may have had a greater impact on estimates of maize GG than those based on a single cross type, GP based exclusively on F1 hybrids and its contribution to GG could be lower than that including different types of crosses. Objective or research questionThe main objectives of this work were to (i) analyze grain yield GP, (ii) dissect grain yield GP into the corresponding trends in its physiological determinants and numerical components, and (iii) estimate the relative contribution of GP to GG in the main maize producing region of Argentina for the period marked by significant changes in heterosis level (i.e. from 1960s to 1990s) and the period of massive adoption of F1 hybrids (from 1990s onwards). MethodsWe used a dataset obtained at the core of the mentioned region (INTA Pergamino; 33°56’S, 60°34’W) from era-decade experiments (ERA) including 24 hybrids released between 1965 and 2016 and grown with no abiotic or biotic restrictions. We quantified GY, its numeric components (KN: kernel number m−2, KW: individual kernel weight) and its physiological determinants (BT: total shoot biomass at maturity, HI: harvest index). ResultsA GP of 0.84 % y−1 was computed for GY from 1965 to 1993, and of 0.51 % y−1 thereafter. We also detected genetic progress for KN (0.53 % y−1) and BT (0.26 % y−1) but not for KW. A GP of 0.66 % y−1 was computed for HI up to 1993, which plateaued thereafter. A 40 % contribution of GP to GG was estimated for the Pergamino site from 1965 to 1993, predominantly driven by changes in heterosis level. The contribution dropped to 32 % from 1993 onwards, when F1 hybrids were massively adopted by the farmers. This contribution was much smaller (e.g. 19 %) in areas less representative of the target population of environments of dominant breeding programs. ConclusionsOur findings underline that the relative contribution of GP to GY improvement at the regional level varies markedly depending upon the period included in the analysis and the environment used for evaluation. The decline observed at less representative locations of the main target population of environments may guide breeders in their decision for developing new programs.

Revealing the three-dimensional structure of microbunched plasma-wakefield-accelerated electron beams

Plasma wakefield accelerators use tabletop equipment to produce relativistic femtosecond electron bunches. Optical and X-ray diagnostics have established that their charge concentrates within a micrometre-sized volume, but its sub-micrometre internal distribution, which critically influences gain in free-electron lasers or particle yield in colliders, has proven elusive to characterize. Here, by simultaneously imaging different wavelengths of coherent optical transition radiation that a laser-wakefield-accelerated electron bunch generates when exiting a metal foil, we reveal the structure of the coherently radiating component of bunch charge. The key features of the images are shown to uniquely correlate with how plasma electrons injected into the wake: by a plasma-density discontinuity, by ionizing high-Z gas-target dopants or by uncontrolled laser–plasma dynamics. With additional input from the electron spectra, spatially averaged coherent optical transition radiation spectra and particle-in-cell simulations, we reconstruct coherent three-dimensional charge structures. The results demonstrate an essential metrology for next-generation compact X-ray free-electron lasers driven by plasma-based accelerators.

Yield Trait and Stability of Chickpea Genotypes for Intensification of Drought‐Prone Rice Fallows of South Asia

ABSTRACTThere is a need for increasing cropping intensity in South Asia including India to ensure food security of burgeoning population. Accordingly, increasing cropping intensity in rainfed rice fallows can be a futuristic strategy. Identification of suitable cultivar and exploration of genetic variability of specific crops/traits are imperative for genetic improvement, drought resistance and yield gain in rice fallows. We evaluated the morphophysiological, yield traits and stability of 15 chickpea genotypes in randomised complete block design for three consecutive years on a drought‐prone rainfed condition of Fluvisol in Kanpur, India. Among genotypes, ‘IPC 2014‐55’, ‘IPC 2015‐44’ and ‘IPC 2011‐92’ had 2%–10% higher relative water content (RWC) over ‘ICC‐92944’ (check cultivar). These genotypes did not differ for total chlorophyll content, root dry weight and nodule dry weight with ‘ICC‐92944’ and ‘KWR 108’ (wider adaptable cultivar of the region). The nitrogen balance index was higher in ‘IPC 2011‐92’, ‘IPC 2014‐88’ and ‘IPC 2014‐55’ by 5%–44% over check cultivar (p < 0.05). The membrane stability index was higher for ‘IPC 2014‐55’ (30%, p < 0.05) and ‘IPC 2011‐92’ (17%, p < 0.05) than ‘ICC‐92944’. ‘IPC 2011‐92’, ‘IPC 2014‐88’ and ‘IPC 2014‐55’ (3 years mean) had 3%–24% higher plant dry weight than ‘ICC‐92944’. Notably, ‘IPC 2014‐55’, ‘IPC 2015‐44’, ‘IPC 2014‐88’ and ‘IPC 2011‐92’ had higher yield attributes such as pods plant−1 by 9%, grain weight plant−1 by 13% and 100‐seed weight by 3% than ‘ICC‐92944’ and ‘KWR 108’ (mean of years). These genotypes had higher mean seed yield than ‘ICC‐92944’ by 23%–42% and ‘KWR 108’ by 7%–23% (p < 0.05). The yield of ‘IPC 2014‐55’, ‘IPC 2015‐44’, ‘IPC 2014‐88’ and ‘IPC 2011‐92’ were stable over years across variable soil and environmental condition as indicated by the genotype × year biplot. Membrane stability index, pods plant−1 and 100‐seed weight were the determinants for increased seed yield of chickpea under drought‐prone condition. Evidently, genotype ‘IPC 2014‐55’, ‘IPC 2015‐44’, ‘IPC 2014‐88’ and ‘IPC 2011‐92’ were better under rainfed rice fallows. These genotypes could be tested under specific drought condition for developing varieties and promoted in rice fallows of South Asia for yield advantage and drought resistance.

Wheat dwarfing reshapes plant and fungal development in arbuscular mycorrhizal symbiosis.

The introduction of Reduced height (Rht) dwarfing genes into elite wheat varieties has contributed to enhanced yield gain in high input agrosystems by preventing lodging. Yet, how modern selection for dwarfing has affected symbiosis remains poorly documented. In this study, we evaluated the response of both the plant and the arbuscular mycorrhizal fungus to plant genetic variation at a major Quantitative Trait Locus called QTL 4B2, known to harbor a Rht dwarfing gene, when forming the symbiosis. We used twelve inbred genotypes derived from a diversity base broadened durum wheat Evolutionary Pre-breeding Population and genotyped with a high-throughput Single Nucleotide Polymorphism (SNP) genotyping array. In a microcosm setup segregating roots and the extra-radical mycelium, each wheat genotype was grown with or without the presence of Rhizophagus irregularis. To characterize arbuscular mycorrhizal symbiosis, we assessed hyphal density, root colonization, spore production, and plant biomass. Additionally, we split the variation of these variables due either to genotypes or to the Rht dwarfing genes alone. The fungus exhibited greater development in the roots of Dwarf plants compared to non-Dwarf plants, showing increases of 27%, 37% and 51% in root colonization, arbuscules, and vesicles, respectively. In addition, the biomass of the extra-radical fungal structures increased by around 31% in Dwarf plants. The biomass of plant roots decreased by about 43% in mycorrhizal Dwarf plants. Interestingly, extraradical hyphal production was found to be partly genetically determined with no significant effect of Rht, as for plant biomasses. In contrast, variations in root colonization, arbuscules and extraradical spore production were explained by Rht dwarfing genes. Finally, when mycorrhizal, Dwarf plants had significantly lower total P content, pointing towards a less beneficial symbiosis for the plant and increased profit for the fungus. These results highlight the effect of Rht dwarfing genes on both root and fungal development. This calls for further research into the molecular mechanisms governing these effects, as well as changes in plant physiology, and their implications for fostering arbuscular mycorrhizal symbiosis in sustainable agrosystems.

Selection index for enhanced yield in rice genotypes

Plant breeding heavily relies on artificial selection to enhance grain yield through various contributing traits. The challenge in selecting complex quantitative traits, such as rice grain yield, lies in low heritability and a significant influence of environmental factors. This study involved 42 rice genotypes with the aim of identifying yield-contributing traits and establishing simultaneous selection models based on discriminant functions. The anticipated genetic gain for grain yield, when all the studied traits were considered in simultaneous selection, was notably higher (445.69%) compared to selecting grain yield alone (13.35%). The discriminant function comprised five traits: plant height (X1), number of filled grains per panicle (X4), number of grains per panicle (X5), seedling vigour index (X6), and grain yield per plant (X7). This combination exhibited a substantial genetic advance of 435.87% and a remarkable relative efficiency of 3264.05%. The relative efficiency of selection, considering grain yield alone, was set at 100%. However, when six ((X1, X3, X4, X5, X6, and X7) and seven traits were simultaneously considered, the efficiency increased to 3044.338 and 3337.606, respectively. Based on the ideal discriminant function, MTU3626 emerged as the best genotype with the highest selection score of 1706.046, followed by SM227 (1669.16) and NDP3 (1555.33). Conversely, MTU1010 ranked last with a selection score of 765.076.

Positive effects of intercrop yields in farms from across Europe depend on rainfall, crop composition, and management

Modern “intensive” agriculture drives the biodiversity-climate crisis but is also central to global food security. Future farming needs management approaches that maintain (or even enhance) food production while reducing negative climate and biodiversity impacts. Intercrops could provide part of the solution, increasing biodiversity and boosting production with fewer inputs. However, barriers remain to their wide-scale uptake, in particular tailoring intercrops to local equipment, management practice, and environment. We analyze data from multiple trials of cereal-legume intercrops conducted on farms across Europe between 2018 and 2021. Our study is the first attempt, to our knowledge, to quantify the yield benefits of cereal-legume intercropping undertaken at commercially relevant scales for farms across Europe. We used crop performance ratio (CPR)—the ratio of the observed intercrop yield compared to the expected yield based on monoculture yields—as our metric of intercrop performance. Using CPR, we found a roughly 30% yield gain across all sites. However, CPR was modulated by a number of factors. CPR was not strongly affected by management except for the negative effects of direct drilling and the positive effects of organic fertilizer addition. CPR also depended on intercrop composition (number and identity of components), background yields (being highest where yields were lower), and rainfall (being higher with higher rainfall). Our findings allow us to reduce uncertainty about how intercrops will perform in realistic local farm conditions, give guidance for tailoring intercrops to local farming conditions, and provide key goals for further work to integrate intercrops into sustainable farming systems.

Synergetic light and cytokinin treatments mitigate the recombinant protein yield depression induced by high-density cultivation of hydroponically-grown Nicotiana benthamiana.

Plant molecular farming is currently operating a transition from soil-based cultures towardhydroponic systems. In this study, we designed a whole-plant NFT (nutrient film technique) platform for the transient expression of influenza virus-like particles harboring hemagglutinin H1 proteins in Nicotiana benthamiana. In particular, we examined the effects of plant density during the post-infiltration expression phase on plant growth and H1 yield in relation to the daily light integral (DLI) received by the crop and the exogenous application of 6-BAP cytokinin (CK). We expected from previous work that high DLI and CK treatments would stimulate the development of highly productive leaves on axillary (secondary) stems and thereby improve the H1 yield at the whole-plant scale. Increasing plant density from 35.7 to 61 plants m-2 during the post-infiltration phase significantly decreased the proportion of axillary leaf biomass by 30% and H1 yield per plant by 39%, resulting in no additional yield gain on a whole-crop area basis. Adding CK to the recirculated nutrient solution decreased the harvested leaf biomass by 31% and did not enhance the relative proportion of S leaves of the plants as previously reported with foliar CK application. There was a 36% increase in H1 yield when doubling the DLI from 14 to 28 mol m-2 s-1, and up to 71% yield gain when combining such an increase in DLI with the hydroponic CK treatment. Contrary to our expectations, leaves located on the main stem, particularly those from the upper half of the plant (i.e.,eighth leaf and above), contributed about 80% of total H1 yield. Our study highlights the significantly different phenotype (~30% less secondary leaf biomass) and divergent responses to light and CK treatments of NFT-grown N. benthamiana plants compared to previous studies conducted on potted plants.

Trends in genetic gain for yam in the IITA breeding program

AbstractMonitoring genetic gain is crucial to ensure breeding programs' effectiveness and identify potential challenges and areas for their improvement. Our study provides a first overview of the trends in genetic gain for tuber yield and disease resistance traits in the IITA's (International Institute of Tropical Agriculture) yam breeding program. We used historical data (2010–2022) from multiple generations of past breeding cycles evaluated at 31 sites in the white Guinea yam (Dioscorea rotundata Poir) breeding pipeline and 28 sites in the water yam (Dioscorea alata L.) breeding pipeline of IITA and its national partners in West Africa. Our result shows positive genetic trends in fresh tuber yield while recording a gain of 1.38% or 99.17 kg ha−1 per year in the white Guinea yam and 2.18% or 252.41 kg ha−1 per year in the water yam breeding pipelines. Genetic trends for virus and anthracnose resistance were in the desired direction but negligible in white Guinea yam, while significant for virus and nonsignificant for anthracnose resistance in water yam. Our findings indicate that while the breeding program has succeeded in enhancing tuber yield, post‐harvest tuber dry matter content and disease resistance (yam mosaic virus and anthracnose) did not follow a similar trend in the material being developed. This implies that the yam breeding program needs to strike a balance between various traits, ensuring that increased yield does not come at a cost to food quality or disease resistance. Our results highlight the importance of continually monitoring and assessing the performance of a breeding program and making informed decisions about which traits to focus on for future improvement.

The use of fixed shelling percentage biases genotype selection in hybrid maize multi-environment yield trials

Context or problemPhenotyping is an integral part of plant breeding operations. In many cases the trait measured is not identical to the target trait for reasons of speed and or cost. This is a form of indirect selection, where correlation between the trait measured and the target phenotype influences the rate of genetic gain. Low correlations lead to slow rates of genetic gain. In sub-Saharan African maize breeding programs, maize grain yield in breeding experimental plots is measured as a field weight (FW), which includes the grain and cob. The weight of grain from each plot is estimated as a standard proportion of grain to total ear weight using a shelling percentage of 80 %. This approach assumes that there is no genetic, environment or genetic by environment interaction in shelling percentage which, if present, would contribute to slower rates of genetic gain for grain yield. Objective or research questionThis study investigated the magnitude of genetic and environmental variation in shelling percentage and its impact on selection in six hybrid maize multi-environment yield trials in Ethiopia over two seasons. MethodsThe data of shelled grain weight (SW) and cob weight (CW) from the trials were analyzed using a bivariate linear mixed model. ResultsGenetic variances for both traits varied across the six testing sites ranging from 0.199 to 2.975 for SW and from 0.029 to 0.245 for CW. The genetic correlations between pairs of sites for SW and CW also varied, indicating the existence of genotype by environment interaction for these traits. Additionally, the bivariate regressions between FW and SW indicated there was substantial genetic deviation around the 80 % shelling response, and this relationship was impacted by environmental influences. ConclusionThe use of a constant relationship of 80 % shelling biases grain yield prediction in multi-environment hybrid maize yield trials and thus reduces the rate of genetic gain in maize breeding programs. Implications or significanceTaking into account the variations in the shelling percentage of the genotypes across sites in predicting grain yield from field weight improves the accuracy of genotype selection and the rate of genetic gain in maize breeding programs.

Enhanced Wind Farm Maintenance Scheduling Including Wake Effects

With the expansion and dissemination of offshore wind farms, the costs associated with asset maintenance and operation become ever more relevant. Among maintenance activities, preventive interventions represent a significant share of the costs and, as opposed to corrective interventions, may be calendarized according to the farm operator’s strategy. In an offshore wind farm there is often aerodynamic interaction between different machines, namely as a given upstream turbine extracts energy from the wind, it will necessarily reduce the energy available for a turbine that is downstream in the farm. This is broadly referred to as wake effects. The relative proximity of turbines within a farm means such an interaction results in lower energy yield for downstream turbines. Maintenance activities require the shutdown of the turbine, hence the turbine under maintenance effectively produces no wake effect. It follows that, depending on weather conditions, the sequence of wind turbines to be deactivated for large preventive maintenance campaigns may impact the total energy production of an offshore wind farm, especially when the wind direction is considered. The present study investigates the potential of incorporating wake effects in the scheduling of offshore wind farm maintenance activities, considering a reference farm layout and using historical climate data for a real offshore site. Different maintenance scenarios are considered, including distinct maintenance vessels and different intervention criteria. Results show there is a small but relevant potential gain in energy yield when the maintenance scheduling is determined including wake effects, with annual energy production increase of up to 0.18% for the parametric values considered.

Selection of high yielding stable forage sorghum genotypes using WAASB and MGIDI methods

Forage sorghum is a versatile and sustainable crop that is less demanding on inputs, produces significant biomass, and is tolerant of drought. In the present study, a set of 30 forage sorghum genotypes, including 21 B–lines and 9 varieties or restorer lines were evaluated under five different environments in Assam and Hyderabad during kharif, rabi and summer 2020–2021 for 12 forage yield related traits. Phenotypic stability was analyzed using multivariate techniques, including the weighted average absolute scores of BLUPs (WAASB) stability index and the multi-trait genotype ideotype distance index (MGIDI). A WAASBY, Y x WAASB bi-plot analysis revealed that genotypes G24 (348B), G25 (424B), and G30 (SSG-59-3) exhibited excellent stability with higher mean performance. MGIDI identified four genotypes, viz., G30 (SSG-59-3), G7 (NSS11B), G19 (327B) and G24 (348B) with higher mean performance and stability for all the 12 studied traits. These selected genotypes exhibited high heritability and genetic gain for green forage yield, indicating their stability and desirability. The strength-weakness plot showed that all selected genotypes were weak contributors to the MGIDI for all traits. This indicates that these genotypes are stable and closer to the ideotype, making them ideal candidates for breeding programs aimed at improving these traits.

Advancements in Genetic Enhancement: CRISPR/Cas-Mediated Genome Editing in Leguminous Crops

Legumes play a crucial role in human nutrition and sustainable agriculture due to their high protein content and health-promoting phytochemicals. To accelerate genetic gain in yield, stress resilience, and nutritional quality, extensive efforts are underway. Recent advancements in genomic resources have paved the way for the application of cutting-edge breeding technologies like genomic selection and genome editing in legume crops. This review focuses on the latest advancements in CRISPR/Cas9-based gene editing technology, specifically tailored for improving traits in legume crops. While successful gene-editing methods have been established for crops like soybean, cowpea, and chickpea, challenges remain, particularly in overcoming the recalcitrance of certain legumes to gene transfer and regeneration in vitro. Strategies to enhance transformation and regeneration rates through modifications in culture methods and DNA delivery are discussed. Despite the potential benefits of gene editing in legume breeding, regulatory barriers pose significant challenges. A comparison of regulatory environments in different regions sheds light on the importance of favourable regulations and public acceptance for realizing CRISPR's potential in enhancing global food security. Additionally, leguminous crops are vital for their nutritional properties, nitrogen-fixing abilities, and contribution to sustainable agriculture. Traditional breeding methods focused on increasing yield, while recent advancements in genome editing techniques, notably CRISPR-Cas technology, have revolutionized the improvement of agronomic traits in legumes. This chapter provides insights into the application of genome editing tools for enhancing traits such as stress tolerance, yield, and seed content in grain legumes. Furthermore, it discusses the challenges and prospects associated with enhancing grain legumes using molecular breeding techniques. Genome editing has been successfully employed in diverse legumes, including model species like Medicago and widely cultivated crops such as soybean and chickpea, offering exciting opportunities for enhancing agronomic characteristics.

Defining the target population of environments for wheat (Triticum aestivum L.) breeding in Italy based on historical data

AbstractGrain yield plateau is a serious concern in many countries, including Italy. A specific‐adaptative strategy might apply to contrast this unfavourable condition. This study aimed to investigate the gain in grain yield and yield‐related traits of bread wheat in Italy over a 16‐year period. A historical dataset concerning 105 sites across Italy and observations on grain yield, heading date, plant height and thousand kernel weight was used. The target population of environments (TPEs) were defined using several environmental parameters. The results showed that while there was a general increase in thousand kernel weight over the 16 years, there was no significant improvement in grain yield and heading date. By contrast, plant height showed a slight decrease over the years. The study also identified five TPEs presenting different climate scenarios in Italy. The TPEs showed varying levels of performance for the traits of interest, with the Po valley (TPE4) showing the highest values for grain yield and thousand kernel weight. The study also identified the best‐performing genotypes for each TPE, providing valuable insights for future wheat breeding programmes in Italy.

Comparing the effects of contact duration on cow and calf performance beyond separation - a prospective cohort study

BackgroundConsumers, the industry, and many farmers have shown increased interest in alternative management systems that allow for cow-calf contact (CCC) and this topic has become an important focus of research for a sustainable dairy industry. Among the many knowledge gaps still existing in this novel research field, there is a need for further research to investigate effects of CCC beyond the nursing period (i.e., after cow-calf separation). Moreover, multi-herd observational studies are scarce. Therefore, the aim of this study was to investigate the within-herd effect of CCC on machine milk yield and calf growth beyond separation. In this prospective cohort study, we studied all cows and their calves (Norwegian Red breed) born between September 1st 2021 and January 31th 2022 at three Norwegian dairy farms, investigating the impact of CCC on machine milk yield and calf average daily gain (ADG) after separation of the cow-calf pair. The follow-up period was 305 d for cows and six months for calves. Machine milk yield was automatically registered at each milking and calf heart girth was measured once a month. As various contact durations emerged, they were categorized into three groups: no contact (NC 0–3 d), short duration (4–30 d) and long duration (> 30 d). Data were analyzed with linear mixed models with the individual animal as the unit of interest. For cows, days in milk (DIM) from date of separation up to 305 DIM were included in the analysis as a continuous variable. For calves, age up to 195 d was used in the statistical analysis.ResultsWe found no differences in machine milk yield after separation across the different contact groups: cows with no contact (n = 28), short duration (n = 51) and long duration (n = 27) of contact, all exhibited comparable milk yields from the time of separation until the end of lactation. Furthermore, in the case of calves, no disparities in average daily gain (ADG) were identified for any of the contact groups: calves with no contact (n = 39), short duration (n = 61) and long duration (n = 38) of contact, displayed comparable growth during the first six months of life.ConclusionsOur findings indicate no negative effects of CCC on machine milk yield after separation, nor any sustained effects on calf growth under the conditions of this study. More multi-herd observational studies conducted on-farm is needed to expand the understanding of effects of CCC on cow and calf performance after separation.

Genetic progress in cowpea [Vigna unguiculata (L.) Walp.] stemming from breeding modernization efforts at the International Institute of Tropical Agriculture.

Genetic gain has been proposed as a quantifiable key performance indicator that can be used to monitor breeding programs' effectiveness. The cowpea breeding program at the International Institute of Tropical Agriculture (IITA) has developed and released improved varieties in 70 countries globally. To quantify the genetic changes to grain yield and related traits, we exploited IITA cowpea historical multi-environment trials (METs) advanced yield trial (AYT) data from 2010 to 2022. The genetic gain assessment targeted short duration (SD), medium duration (MD), and late duration (LD) breeding pipelines. A linear mixed model was used to calculate the best linear unbiased estimates (BLUE). Regressed BLUE of grain yield by year of genotype origin depicted realized genetic gain of 22.75 kg/ha/year (2.65%), 7.91 kg/ha/year (0.85%), and 22.82 kg/ha/year (2.51%) for SD, MD, and LD, respectively. No significant gain was realized in 100-seed weight (Hsdwt). We predicted, based on 2022 MET data, that recycling the best genotypes at AYT stage would result in grain yield gain of 37.28 kg/ha/year (SD), 28.00 kg/ha/year (MD), and 34.85 kg/ha/year (LD), and Hsdwt gain of 0.48g/year (SD), 0.68g/year (MD), and 0.55g/year (LD). These results demonstrated a positive genetic gain trend for cowpea, indicating that a yield plateau has not yet been reached and that accelerated gain is expected with the recent integration of genomics in the breeding program. Advances in genomics include the development of the reference genome, genotyping platforms, quantitative trait loci mapping of key traits, and active implementation of molecular breeding.

Enhanced radiation use efficiency and grain filling rate as the main drivers of grain yield genetic gains in the CIMMYT elite spring wheat yield trial

Common wheat (Triticum aestivum L.) is a major staple food crop, providing a fifth of food calories and proteins to the world’s human population. Despite the impressive growth in global wheat production in recent decades, further increases in grain yield are required to meet future demands. Here we estimated genetic gain and genotype stability for grain yield (GY) and determined the trait associations that contributed uniquely or in combination to increased GY, through a retrospective analysis of top-performing genotypes selected from the elite spring wheat yield trial (ESWYT) evaluated internationally during a 14-year period (2003 to 2016). Fifty-six ESWYT genotypes and four checks were sown under optimally irrigated conditions in three phenotyping trials during three consecutive growing seasons (2018–2019 to 2020–2021) at Norman E. Borlaug Research Station, Ciudad Obregon, Mexico. The mean GY rose from 6.75 (24th ESWYT) to 7.87 t ha−1 (37th ESWYT), representing a cumulative increase of 1.12 t ha−1. The annual genetic gain for GY was estimated at 0.96% (65 kg ha−1 year−1) accompanied by a positive trend in genotype stability over time. The GY progress was mainly associated with increases in biomass (BM), grain filling rate (GFR), total radiation use efficiency (RUE_total), grain weight per spike (GWS), and reduction in days to heading (DTH), which together explained 95.5% of the GY variation. Regression lines over the years showed significant increases of 0.015 kg m−2 year−1 (p < 0.01), 0.074 g m−2 year−1 (p < 0.05), and 0.017 g MJ−1 year−1 (p < 0.001) for BM, GFR, and RUE_total, respectively. Grain weight per spike exhibited a positive but no significant trend (0.014 g year−1, p = 0.07), whereas a negative tendency for DTH was observed (− 0.43 days year−1, p < 0.001). Analysis of the top ten highest-yielding genotypes revealed differential GY-associated trait contributions, demonstrating that improved GY can be attained through different mechanisms and indicating that no single trait criterion is adopted by CIMMYT breeders for developing new superior lines. We conclude that CIMMYT’s Bread Wheat Breeding Program has continued to deliver adapted and more productive wheat genotypes to National partners worldwide, mainly driven by enhancing RUE_total and GFR and that future yield increases could be achieved by intercrossing genetically diverse top performer genotypes.