Basal Grain Research Articles

Near-α titanium alloy dwell load-induced deformation twinning to coordinate the deformation mechanism associated with crack initiation

In this study, we identified a specific phenomenon of coordinated deformation of twins in near-α titanium alloys during dwell fatigue (DF). The main crack source regions and internal cracks in the micro-texture region (MTR) and no-MTR samples with inconsistent orientation characteristics were characterized. The results demonstrate that the main cracks in all specimens are aligned with the (0001) basal plane, which is associated with basal slip. Notably, twins are found and confirmed to be involved in the DF crack initiation process in high Al content near-α Ti60 alloys where deformation twins are rare, and tend to nucleate at the DF basal cracks. Further in-situ dwell investigation reveals and proposes that the dislocation pile-up and prismatic-basal (PB) interfacial features between soft/hard grains lead to deformation twin nucleation and growth from hard grain boundaries. Concurrently, the pyramidal 〈c+a〉 dislocation slip is observed to be in concurrent operation with the induced twins. These findings suggest that deformation twins not only coordinate basal grain deformation but also hinder the initiation and propagation of basal cracks caused by basal 〈a〉 slip. Moreover, a high density of pyramidal 〈c+a〉 dislocations within the twin and their dissociation to form basal stacking faults (SFTs) with a specific nanometric spacing make the twinning process accompanied by significant lattice distortions inside the twin. These newly formed nanotwin boundaries and SFTs act as barriers to dislocation motion, enhancing the strength and DF lifetime of near-α Ti60 alloys and effectively reducing the dwell sensitivity of no-MTR alloys. Our findings extend the understanding of the coordinated roles of dislocation slip, twin nucleation and formation of basal SFTs in near-α titanium alloys in dwell fatigue.

Application of Open Panicle Traits in Improving the Filling Characteristics at the Base of Indica Rice Panicles.

Panicle-type structure is an important factor affecting rice yield, and an excellent panicle type has become a key indicator in rice breeding. In this study, the indica rice variety R766, which has an open panicle type, was obtained through natural mutation and hybrid selection. Through analyzing differences in panicle structure, panicle yield, and chemical composition between open panicle rice R766 and conventional panicle rice R2928, we found that the angles of the middle and lower branches in R766 were 186.99% and 135.93% greater than those in R2928, respectively. By comparing the grain-filling characteristics of different panicle positions in the two rice varieties, we found that the grain filling at the middle and lower panicle positions of R2928 was significantly lower, accompanied by an increase in the percentage of empty spikelets. However, in R766, the grain-filling rates in the middle and lower panicle positions were consistent with those in the upper panicle position, with significantly higher rates of grain filling and grain plumpness in the middle and lower panicle positions than in R2928. The empty grain rate at the lower panicle position of R766 was 15.25% lower than that of R2928, and the grain filling was 24.75% higher than that of R2928. Additionally, the variation in the 1000-grain weight of grains at different panicle positions in R766 was relatively small, with decreases of 1.55% and 0.38% in the middle and lower panicle positions, respectively, compared with the upper position, whereas R2928 showed decreases of 5.99% and 7.12% in the 1000-grain weight of grains at the middle and lower panicle positions, respectively, compared with the upper position. The cellulose content in the stems of R766 was 7.51% higher than that of R2928, with no significant difference in the cellulose content in the panicle axis and primary branches compared to R2928. The lignin content of the panicle axis in R766 was 8.03% higher than that in R2928, whereas there was no significant difference between the lignin content of the stems and primary branches. This preliminary study revealed the open panicle characteristics of R766 and the reasons for its high basal grain setting rate. This study provides a reference for promoting this open panicle-type indica rice variety to improve yield and disease resistance in environments with high humidity and low sunlight levels.

Condensed tannin-induced variations in the rumen metabolome and the correlation with fermentation characteristics in goats.

In this study, we characterized the effects of CT dietary inclusion at 2% (wt/wt) dry matter on the goat rumen metabolome and fermentation characteristics. Barley (BA) and corn (CN) were separately used as basal grain for the control rations, and rations supplemented with CT were BACT and CNCT, respectively. The rations were tested using eight Japanese Shiba × Saanen goats in a replicated 4 × 4 Latin square arrangement (28 days for each period). Ruminal fluid was obtained on day 25 of each period, and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) analysis was performed. Metabolites from BACT against BA and CNCT against CN were mostly associated with purine metabolism. Moreover, BACT against BA showed intensified biosynthesis of unsaturated fatty acids, and CNCT against CN resulted in strengthened amino acid metabolism. Furthermore, strong correlations were observed between rumen NH3 -N and the copy number of total bacteria with most of the differential metabolites. The present paper provides a better understanding of the relationship between the rumen metabolome and fermentation characteristics and supports a shift in concern about using CT as a strategy to manipulate rumen metabolism.

Long-period stacking ordered phase kinking, twinning behavior and dynamic recrystallization of Mg-Gd-Y-Zn-Zr alloy under severe shear deformation

A novel severe shear specimen with a maximum shear strain of 3 was designed to further clarify kinking and fragment behavior of long period stacking ordered (LPSO) phases, as well as their interaction with twinning behavior and dynamic recrystallization (DRX) behavior under severe shear deformation (SSD). The results indicate that promoted kinking and fragment behavior for LPSO phases is obseved for hihger activation of basal <a> dislocations induced by shear deformation. Besides the known crack causd by LPSO kinking, a new fragment process without kink bands formation is found for block-shaped LPSO phases under SSD, which follows three stages of micro-crack at the interface of LPSO/α-Mg matrix, crack and crush. Moreover, the actvition of tension twinning detected at kinked boundaries is reveled to be controlled by the combined effect of LPSO kinking and shear stress state. Specifically, crystal rotation related to LPSO kinking reorient grains to be possbile for twinning, and then high effective Schmid factor (ESF) under shear stress furter prioritise the twining acivaiton. Additionally, orientation dependence of DRX behaviors was weakened due to the particle-stimulated nucleation (PSN) mechanism caused by interdendritic block-shaped LPSO phases, which can accelerate the formation of low angle grain boundaries and DRX grains by activated pyramidal <c+a> slip systems even at basal grains.

High-temperature fracture behaviour of layered alumina ceramics with textured microstructure

Mimicking the damage tolerance of biological materials such as nacre has been realised in textured layered alumina ceramics, showing improved reliability as well as fracture resistance at room temperature. In this work, the fracture behaviour of alumina ceramics with textured microstructure and laminates with embedded textured layers are investigated under uniaxial bending tests at elevated temperatures (up to 1200°C). At temperatures higher than 800°C monolithic textured alumina favours crack deflection along the basal grain boundaries, corresponding to the transition from brittle to more ductile behaviour. In the case of laminates, the loss of compressive residual stresses is counterbalanced by the textured microstructure, effective up to 1200°C. This study demonstrates the potential of tailoring microstructure and architecture in ceramics to enhance damage tolerance within a wide range of temperatures.

Investigating the Microstructure, Crystallographic Texture and Mechanical Behavior of Hot-Rolled Pure Mg and Mg-2Al-1Zn-1Ca Alloy

In this study, the microstructure, crystallographic texture and the mechanical performance of hot-rolled pure Mg and Mg-2Al-1Zn-1Ca (herein inferred as AZX211) were thoroughly investigated. The results showed that the designed AZX211 alloy exhibited an exceptional strength/ductility synergy where an almost 40% increase in ductility was received for AZX211. The microstructural characterization revealed the grain refinement in the AZX211, where the grain size was reduced by more than 50% (24.5 µm, 10 µm for the pure Mg and the AZX211, respectively). Moreover, a discernible number of precipitates were dispersed in the AZX211, which were confirmed to be (Mg, Al)2Ca. The pure Mg showed a conventional strong basal texture while a significantly weakened split basal texture was received for the AZX211. The fraction of basal-oriented grains was 21% for the pure Mg and 5% for the AZX211. The significant texture weakening for the AZX211 can be attributed to the precipitation and co-segregation that triggered the preferential evolution of the non-basal grains while impeding the growth of the basal grains. This was also confirmed by the crystal orientation and the pseudo-rocking curves. The higher ductility of the AZX211 was explained based on the texture softening and Schmid factor for the basal and non-basal slip systems.

Mechanisms of Submarine Debris Flow Growth

AbstractSubmarine debris flows are among the largest types of landslide on planet Earth. They occur under the cloak of the sea so little is known about how they reach such large volumes. Field evidence suggests that the entrainment from the sediment‐rich sea floor enables the growth of submarine debris flows. However, there is a dearth of understanding of the dynamic processes of entrainment. In this study, a new entrainment model is proposed for submarine debris flows with different clay contents. The entrainment model considers the relative contributions from basal grain friction and fluid viscous stresses that drive the entrainment process, and the effects of hydroplaning. To evaluate the new model, a new experimental setup is developed to simulate submarine debris flows, with clay contents from 4% to 12%, overriding and entraining a loose sand bed. The clay content is found to have profound effects on the entrainment dynamics. Flows with high clay contents (i.e., ≥10%) hydroplane, which enhances the mobility of the flow but reduces its entrainment potential. The predicted entrainment depths from the proposed model are consistent with the measured ones from the experiments. The proposed theoretical model and unique experimental evidence can be used as guiding tools to progress toward the inclusion of entrainment in vulnerability assessments of offshore infrastructure.

Effect of water and mercury quenching on microstructure and mechanical behavior of room temperature rolled Zircaloy-2

The present study investigates the effect of water and mercury quenching on the microstructural and mechanical behavior of room temperature rolled Zircaloy-2. Solution treatment of zircaloy-2 at 1073 K followed by quenching in mercury and water has been performed prior to rolling. Different reduction from 25% to 85% of the quenched alloy and further characterization has been performed by tensile testing, Electron back scattered diffraction (EBSD) and Transmission Electron Microscopy (TEM). Enhanced tensile strength (745 MPa) after 85% rolling reduction was obtained compared to 389 MPa after water quenching. Rolling reduction results an increase in the dislocation density, thereby enhancing the mechanical strength. Initial deformation has been observed by the activation of extension twinning from EBSD microstructure. Twinning results the inclination of ‘c’ axis towards the normal direction which makes near basal grains orientation along the deformation direction. Due to hard orientation i.e. ‘c’ axis aligned along the loading direction, the grain fragmentation is heterogeneous. Grain fragmentation leads to improvement in the ductility with minimal loss in strength owing to rearrangement of dislocations after annealing at 400 o C for 30 minutes. By optimizing the annealing temperature (400 o C for 30 minutes) bulk ultrafine grained zircaloy-2 have been produced in 85% room temperature rolled zircaloy-2.

The evolution of coarse grains and its effects on weakened basal texture during annealing of a cold-rolled magnesium AZ31B alloy

The nucleation, grain growth of 34 coarse grains during annealing were tracked using a quasi-in-situ EBSD method. These 34 coarse grains had different orientations and most grains were non-basal orientated. No preferable grain growth or special types of grain boundaries were identified. Only 9 coarse grains nucleated from deformed grain boundaries due to initial large grain size and limited grain boundary volume fraction. The main nucleation site of 34 coarse grains was dislocation cells or subgrains in deformed grain interiors. Their recrystallisation behaviour can be illustrated by abnormal subgrain growth (AsGG) rarely reported in Mg alloys. The coarse basal grains showed no growth advantage in terms of grain size or number over other non-basal grains, leading to a weak basal texture in AZ31B alloy.

Diurnal Ruminal pH and Temperature Patterns of Steers Fed Corn or Barley-Based Finishing Diets.

Simple SummaryCattle in feedlots are typically fed diets with a high proportion of cereal grains. While feeding high-energy grain-based diets is advantageous for growth and performance, it can also contribute to an increased likelihood of metabolic issues. Different feedstuffs have unique digestive utilization, which may lead to different cattle performance outcomes. Barley is fermented to a greater extent in the rumen, compared to corn, and can lead to an increased likelihood of digestive disorders. To further our understanding of the use of barley and corn in cattle feedlot diets, we evaluated the effect of diets on ruminal pH, temperature and feed intake events using continuous rumen monitoring technology. While mean ruminal pH was not different between corn or barley-fed steers, barley-fed steers had greater ruminal pH change throughout a 24 h period. Barley-fed steers also exhibited greater variation in ruminal pH. Additionally, intake patterns were different between corn- and barley-fed steers in which corn-fed steers consumed more feed the first 6 h directly after feeding while barley-fed steers consumed more feed later in the day. Presumably these intake patterns could be influenced by differences in the diurnal patterns of ruminal pH between corn and barley. By evaluating ruminal dynamics on a diurnal scale, we will enhance our understanding of utilization of different feedstuffs in beef feedlot diets.This study evaluated the effects of corn or barley finishing diets on ruminal pH and temperature and their relationship to feed intake events using continuous reticulorumen monitoring of feedlot steers. Average daily ruminal pH and temperature were not impacted (p ≥ 0.17) by diet. However, diet did affect daily variation of ruminal pH and temperature (p < 0.01). Average hourly ruminal pH displayed a diet by hour post-feeding interaction (p < 0.01), where barley-fed steers had greater (p < 0.01) ruminal pH than corn-fed steers at 0, 1, 18, 19, 20, 21, 22 and 23 h post feeding, but had lower (p ≤ 0.05) ruminal pH than corn-fed steers at 6, 7, and 8 h post-feeding. Variation in ruminal pH hour post-feeding also displayed a diet by hour post-feeding interaction (p < 0.01), where barley-fed steers had greater (p ≤ 0.03) variation in ruminal pH at hours 1–17 post-feeding but did not differ (p ≥ 0.16) at 0, 18, 19, 20, 21, 22 and 23 h post-feeding. Additionally, average hourly ruminal temperature exhibited a diet by hour post-feeding interaction (p < 0.01). In summary, basal grain interacted with time post-feeding influencing ruminal pH and temperature in feedlot steers.

The role of Ga in the microstructure, corrosion behavior and mechanical properties of as-extruded Mg–5Sn–xGa alloys

The effect of Ga element on microstructure, corrosion behavior and tensile mechanical properties of as-extruded Mg–5Sn–xGa (x = 0, 1, 2, 3, all in wt%) alloys was investigated using immersion test, electrochemical test and tensile test. The results show that the Mg2Sn and Mg5Ga2 particles are dynamically precipitated during extrusion process, and the volume fraction of Mg5Ga2 precipitates increases with increasing Ga content. The corrosion resistance of Mg–5Sn alloy in the immersion test is increased approximately by four times after adding 2 wt% Ga, due to the fact that the Ga element weakens the cathodic reaction, and more stable corrosion products are formed in the Ga-containing alloys in the inner corrosion layer. The tensile strength of investigated alloys is improved monotonously with increasing Ga content. The maximum elongation to fracture reaches up to 21.7% for Mg–5Sn–1Ga alloy due to the modified basal grain texture.

Effect of Grain Orientation on Indentation Induced Creep in Pure Zinc

Abstract The study presents the anisotropy in the indentation creep response of zinc. Indentation creep tests were conducted on grains with three different orientations, namely, 〈0001〉, ⟨112¯0⟩, and ⟨101¯0⟩. Indentation creep along the 〈c〉 axis showed a pronounced creep exhibiting a 25% higher creep displacement as compared with indentation perpendicular to the 〈c〉 axis. However, the recovery observed was the highest for basal-oriented grains wherein a recovery of 50% to its indented depth was observed, whereas for ⟨112¯0⟩ the recovery observed was 30%. The stress exponent, n, was obtained by employing two different approaches for each of the orientations and a difference in the stress exponent value was also observed, highlighting the anisotropic creep response. Basal and non-basal oriented grains showed a lower (n ≅ 1.6) and higher stress exponent (n ≅ 5), respectively, highlighting the different operable creep mechanism. Surface topography using atomic force microscope (AFM) revealed twinning and sink-in for ⟨112¯0⟩ and ⟨101¯0⟩, whereas uniform pile up was observed for basal grain.

Irradiation damage in nuclear graphite at the atomic scale

Microstructures of nuclear graphite have been investigated based on the analysis of both X-ray diffraction patterns and High Resolution Transmission Electron Microscopy images (HRTEM) from experiments and from molecular dynamics simulations. One filler particle – composed of almost aligned crystallites separated by Mrozowski cracks – and the whole sequence of single crystal graphite irradiated from its virgin state up to highly damaged (64.5% of defects) have been simulated. Simulations are assessed against experiments based on the analysis of its microstructures extracted with Bragg's law and Scherrer's equation applied to simulated X-ray diffraction patterns. In particular, the evolution of cell parameters with defect concentration generated by irradiation agrees well with experimental observations. Simulated HRTEM images show many features observed in experimental images in both virgin and irradiated French nuclear graphite. Some of these features can be linked unequivocally to defined atomistic configurations. Basal grain boundaries (GBs), Mrozowski cracks, graphene sheets and their folding belong to this category. Conversely, some patterns in simulated HRTEM cannot be related to a unique atomistic configuration and might eventually give rise to misleading interpretation. This is evidenced for edge dislocations in virgin nuclear graphite as well as for residues of graphene layers in highly damaged graphite.

Experimental Investigation on the Effects of the Fixed Boundaries in Channelized Dry Granular Flows

The dynamics of granular mixtures, involved in several geophysical phenomena like rock avalanches and debris flows, is far from being completely understood. Several features of their motion, such as non-local and boundary effects, still represent open problems. An extensive experimental study on free-surface channelized granular flows is here presented, where the effects of the fixed boundaries are systematically investigated. The entire experimental data set is obtained by using a homogenous acetal-polymeric granular material and three different basal surfaces, allowing different kinematic boundary conditions. Velocity profiles at both the sidewall and the free surface are obtained by using high-speed cameras and the open-source particle image velocimetry code, PIVlab. Significantly, different sidewall velocity profiles are observed by varying the basal roughness and the flow depth. Owing to sidewall friction and non-local effects, such profiles exhibit a clear rheological stratification for high enough flow depths and they can be well described by recurring to composite functions, variously formed of linear, Bagnold and exponential scalings. Moreover, it has been discovered that transitions from one velocity profile to another are also possible on the same basal surface by merely varying the flow depth. This shape transition is due partly to the sidewall resistances, the basal boundary condition and, in particular, the occurrence/inhibition of basal grain rolling. In most of the experiments, the normal-to-bed velocity profiles and the velocity measurements at the free surface strongly suggest the occurrence of a secondary circulating flow, made possible by a chiefly collisional regime beneath the free surface.

Microstructure Stability of a Fine-Grained AZ31 Magnesium Alloy Processed by Constrained Groove Pressing During Isothermal Annealing

In this study, an AZ31 magnesium alloy plate was processed by constrained groove pressing (CGP) under three deformation cycles at temperatures from 503 to 448 K. The process resulted in a homogeneous fine grain microstructure with an average grain size of 1.8 μm. The as-processed microstructure contained a high fraction of low-angle grain boundaries (LAGB) of subgrains and dislocation boundaries that remained in the structure due to incomplete dynamic recovery and recrystallization. The material's yield strength was found to have increased from 175 to 242 MPa and with a significant weakening of its initial basal texture. The microstructure stability of the CGP-processed material was further investigated by isothermal annealing at temperature from 473 to 623 K and for different time. Abnormal grain growth was observed at 623 K, and this was associated with an increased in nonbasal grains at the expense of basal grains. The effect of annealing temperature and time on the grain growth kinetics was interpreted by using the grain growth equation, Dn+D0n=kt, and Arrhenius equation, k=k0 exp (−(Q/RT)). The activation energy (Q) was estimated to be 27.8 kJ/mol which was significantly lower than the activation energy for lattice self-diffusion (QL = 135 kJ/mol) and grain boundary diffusion (Qgb = 92 kJ/mol) in pure magnesium. The result shows that grain growth is rapid but average grain size still remained smaller than the as-received material, especially at the shorter annealing time.

Instability of the expression of morphological and phenological descriptors to environmental variation in white oat

Morphological and phenological characters are used in the selection, breeding, and description of plant varieties with varying genotypes. The stability of these descriptors in the face of environmental changes can determine their usefulness in situations where plant varieties must be reliably identified. The objective of this study was to verify the expression of morphological and phenological descriptors and use them to distinguish between white oat cultivars (Avena sativa L.) in two growing periods. For this, five cultivars, protected and belonging to four breeders, referred to as G1, G2, G3, G4, and G5, were sown in the typical growing season in southern Brazil (autumn-winter) and outside that period (winter-spring), and grown for forty days. The experiment was established in the field, in a randomized block design replicated three times. The cultivars were evaluated for 42 descriptors (15 quantitative and 27 qualitative). Quantitative data were analyzed by analysis of variance, the comparison of averages, and multivariate analysis by generating average euclidean distances. Qualitative data were analyzed by mode determination, followed by obtaining the similarity index. The relationship between cultivars was illustrated by dendrograms. The stability index for each descriptor was calculated. A genotype x environment interaction was observed for 28 descriptors. The stability of descriptor appearance and persistence over the growing season was higher in qualitative (44%) than in quantitative (7%) descriptors. The most stable qualitative descriptors were lemma color, hairiness of the upper node, flag leaf position, hairiness of the base of the grain, basal grain length, and rachilla length. The most stable quantitative descriptor was flag leaf length. Shifting the white oat growing season from autumn-winter to winter-spring reduced the cycle and modified the expression of most descriptors by changing the phenotypic distinctness between cultivars.

Strain hardening of Titanium alloy Ti6Al4V sheets with prior heat treatment and cold working

Strain hardening of Titanium alloy Ti6Al4V has been studied at four different strain rates (10−4 to 10−1s−1) under tensile loading at four different heat treatment conditions viz. mill annealing (MA), recrystallization annealing (RA), solution treatment (ST) and solution treatment and aging (STA). Effect of prior cold working before tensile testing has also been studied. Strain hardening exponent (n) is found to be decreasing with increasing strain rates for samples in all the four heat treatment conditions, whereas trend is found to be opposite in case, of cold worked (~15%) samples prior to tensile testing. This is due to rearrangement of dislocations generated during the prior cold working. Strength coefficient (K) is also found to follow similar trend.Optical microstructure clearly showed two phase (α+β) structure in all the samples and completely fragmented grain boundaries in cold worked condition. Non-basal oriented grains in as-annealed samples and higher volume fraction of basal (0001) grains in annealed and cold worked samples were observed along with fragmented grain boundaries/regions of void coalescence. Low angle misorientation was found to be lower in sample subjected to STA heat treatment as compared to other heat treated conditions. Twinning was observed in ST as well as in STA conditions, which was absent in annealed as well as annealed and cold worked samples.Image quality maps revealed regions of low image quality in deformed samples indicating presence of high dislocation density. Regions of void coalescence were confirmed by KAM (Kernel average misorientation) maps, GOS (grain orientation spread) maps and unique grain colour maps. Analysis of fractographs showed ductile mode of fracture in all heat treated conditions and mixed mode of fracture with fragmented grain boundaries in all samples subjected to heat treatment followed by tensile testing with prior cold working.

Quantitative analysis of orientation and near neighbor interaction effects during deformation of polycrystalline Ti6Al4V

The effect of orientation and interaction with neighboring grains in polycrystalline Ti6Al4V deformation are quantified using interrupted deformation coupled with microstructure analysis. It is shown that softer grains accommodate more strain compared to hard basal grains, which can be explained in terms of their resolved shear stress and critical resolved shear stress. Grains with similar orientations follow different orientation trajectories during deformation depending on their misorientation with respect to neighboring grains. The influence of near neighbor interaction is quantified using a new parameter, average nearest neighbor misorientation (NNM). The NNM accurately predicts similarities and differences in the evolution of grain orientations during deformation.

Subsequent growth performance and digestive physiology of broilers fed on starter diets containing spray-dried porcine plasma as a substitute for meat meal

A 4 × 2 factorial experiment was conducted to investigate the effect of inclusion of spray-dried porcine plasma (SDPP), in lieu of meat meal, in the starter diet on performance and digestive physiology of broiler chickens between hatch and 35 d of age. Four levels of SDPP (0, 5, 10 or 20 g/kg) were included in the starter diets in lieu of meat meal on either wheat- or maize-based diets.Over the first 10 d, and throughout the 35-d experimental period, birds gained more body weight with increasing concentrations of SDPP regardless to the type of grain used. Inclusion of SDPP in the starter diet markedly improved feed per gain in the starter phase and across the 35-d study. There was no significant effect of the type of grain and its interaction with SDPP on the body weight gain and feed per gain for the two assessed periods.At d 10, the relative weight of the gizzard+proventriculus, spleen and liver increased with increasing concentrations of SDPP.At 24 d of age, the grain and SDPP inclusion significantly interacted, depressing the weight of bursa and spleen in birds that received the highest concentration of SDPP in the maize-based diet. Birds fed on the maize-based diets had higher relative weight of pancreas than those on the wheat-based diets.Increasing concentrations of SDPP in the starter diet improved the activities of maltase, sucrase and alkaline phosphatase at 24 d of age. The interaction of grain and SDPP concentration was significant for sucrase activity in birds on the wheat-based diets. Chickens on maize-based diets had higher alkaline phosphatase and maltase activities than those on wheat-based diets.Chicks that were offered SDPP-containing starter diets had longer villi, deeper crypts and lower villi/crypt than the control at 24 d of age regardless of the grain type used. Furthermore, longer villi and larger villi/crypt were found in chicken groups fed on wheat-based diets than those on maize-based diets.Chickens on maize-based diets had higher dressing percentage and relative breast weight than those on wheat-based diets at 35 d of age.It can be concluded that supplementation of starter diets with SDPP would be beneficial to the long-term growth of broiler chickens. The effect of the basal grain used in the diet is minimal.

Carpel size, grain filling, and morphology determine individual grain weight in wheat.

Individual grain weight is a major yield component in wheat. To provide a comprehensive understanding of grain weight determination, the carpel size at anthesis, grain dry matter accumulation, grain water uptake and loss, grain morphological expansion, and final grain weight at different positions within spikelets were investigated in a recombinant inbred line mapping population of bread wheat (Triticum aestivum L.)×spelt (Triticum spelta L.). Carpel size, grain dry matter and water accumulation, and grain dimensions interacted strongly with each other. Furthermore, larger carpels, a faster grain filling rate, earlier and longer grain filling, more grain water, faster grain water absorption and loss rates, and larger grain dimensions were associated with higher grain weight. Frequent quantitative trait locus (QTL) coincidences between these traits were observed, particularly those on chromosomes 2A, 3B, 4A, 5A, 5DL, and 7B, each of which harboured 16-49 QTLs associated with >12 traits. Analysis of the allelic effects of coincident QTLs confirmed their physiological relationships, indicating that the complex but orderly grain filling processes result mainly from pleiotropy or the tight linkages of functionally related genes. After grain filling, distal grains within spikelets were smaller than basal grains, primarily due to later grain filling and a slower initial grain filling rate, followed by synchronous maturation among different grains. Distal grain weight was improved by increased assimilate availability from anthesis. These findings provide deeper insight into grain weight determination in wheat, and the high level of QTL coincidences allows simultaneous improvement of multiple grain filling traits in breeding.