Mature Grains Research Articles

De novo Expression of β-amylase2 (Bmy2) in Barley Grains During Micromalting

β-Amylase is important to the malting and brewing industry because it is one of four main enzymes involved in fermentable sugar production during mashing. There are two functional barley β-amylases encoded by the Bmy1 and Bmy2 genes. Mashing is commonly performed at high temperatures and β-amylase1 (Bmy1) is vulnerable to thermal inactivation at these temperatures. Unlike Bmy1, Bmy2 is not stored at useful levels in the mature grain but Bmy2 encodes a more thermostable β-amylase. Expression of β-amylase is not thought to occur during malting but, interestingly, de novo expression of Bmy2 is seen in other Triticeae tribe members during germination. Therefore, this research was conducted to determine if barley Bmy2 is de novo expressed during micromalting. De novo expression of Bmy2 is observed in both a two- and six-row malting cultivar (Conrad and Legacy, respectively). Legacy Bmy2 transcript levels significantly increased (40-fold) between 0 and 4 Days of Germination (DoG) and Conrad Bmy2 transcript levels significantly increased (20-fold) between 0 and 3 DoG. Legacy had significantly (1.9-fold) more Bmy2 transcript levels than Conrad by the end of micromalting. The β-amylase activity and protein immunoblots corroborated the gene expression data thus reliably demonstrating the de novo expression of Bmy2 during micromalting.

Introgression of chromosomal segments conferring early heading date from wheat diploid progenitor, Aegilops tauschii Coss., into Japanese elite wheat cultivars.

The breeding of agriculturally useful genes from wild crop relatives must take into account recent and future climate change. In Japan, the development of early heading wheat cultivars without the use of any major gene controlling the heading date is desired to avoid overlap of the harvesting time before the rainy season. Here, we backcrossed two early heading lines of a synthetic hexaploid wheat, derived from a crossing between durum wheat and the wild wheat progenitor Aegilops tauschii, with four Japanese elite cultivars to develop early heading lines of bread wheat. In total, nine early heading lines that showed a heading date two to eight days earlier than their parental cultivars in field conditions were selected and established from the selfed progenies of the two- or three-times backcrossed populations. The whole appearance and spike shape of the selected early heading lines looked like their parental wheat cultivars. The mature grains of the selected lines had the parental cultivars' characteristics, although the grains exhibited longer and narrower shapes. RNA sequencing-based genotyping was performed to detect single nucleotide polymorphisms between the selected lines and their parental wheat cultivars, which revealed the chromosomal regions transmitted from the parental synthetic wheat to the selected lines. The introgression regions could shorten wheat heading date, and their chromosomal positions were dependent on the backcrossed wheat cultivars. Therefore, early heading synthetic hexaploid wheat is useful for fine-tuning of the heading date through introgression of Ae. tauschii chromosomal regions.

Late-maturity α-amylase expression in wheat is influenced by genotype, temperature and stage of grain development.

Late-maturity α-amylase (LMA) expression in wheat grains can be induced by either a cool temperature shock close to physiological maturity or continuous cool maximum temperatures during grain development. Late-maturity α-amylase (LMA) is a genetic trait in wheat (Triticum aestivum L.) involving the production of α-amylase during grain development, which can result in an unacceptably low Falling Number (FN) in mature grain and consequent grain downgrading. Comparison of the FN test, an α-amylase activity assay and a high pI α-amylase-specific ELISA on the same meal samples gave equivalent results; ELISA was used for further experiments because of its isoform specificity. A cool temperature shock during the middle stages of grain development is known to induce LMA and is used for phenotypic screening. It was determined that a cool temperature treatment of seven days was required to reliably induce LMA. Glasshouse studies performed in summer and winter demonstrated that temperature affected the timing of sensitivity to cool-shock by altering the rate and duration of grain development, but that the sensitive grain developmental stage was unchanged at 35-45% moisture content. Wheat varieties with Rht-B1b or Rht-D1b dwarfing genes responded to a cool-shock only from mid grain filling until physiological maturity, whilst genotypes with Rht8c or without a dwarfing gene expressed LMA in response to a cool-shock during a wider developmental range. A continuous cool maximum temperature regimen (23°C/15°Cday/night) during grain development also resulted in LMA expression and showed a stronger association with field expression than the cool-shock treatment. These results clarify how genotype, temperature and grain developmental stage determine LMA expression, and allow for the improvement of LMA phenotypic screening methods.

Cadmium distribution in mature durum wheat grains using dissection, laser ablation-ICP-MS and synchrotron techniques

Understanding how essential and toxic elements are distributed in cereal grains is a key to improving the nutritional quality of cereal-based products. The main objective of this work was to characterize the distribution of Cd and of nutrients (notably Cu, Fe, Mn, P, S and Zn) in the durum wheat grain. Laser ablation inductively coupled mass spectrometry and synchrotron micro X-ray fluorescence were used for micro-scale mapping of Cd and nutrients. A dissection approach was used to quantitatively assess the distribution of Cd and nutrients among grain tissues. Micro X-ray absorption near-edge spectroscopy was used to identify the Cd chemical environment in the crease. Cadmium distribution was characterized by strong accumulation in the crease and by non-negligible dissemination in the endosperm. Inside the crease, Cd accumulated most in the pigment strand where it was mainly associated with sulfur ligands. High-resolution maps highlighted very specific accumulation areas of some nutrients in the germ, for instance Mo in the root cortex primordia and Cu in the scutellum. Cadmium loading into the grain appears to be highly restricted. In the grain, Cd co-localized with several nutrients, notably Mn and Zn, which challenges the idea of selectively removing Cd-enriched fractions by dedicated milling process.

Characterization of the development of cowpea cultivars and of the quantity and quality of proteins in their grains

Abstract: The objective of this work was to evaluate cowpea (Vigna unguiculata) cultivars regarding plant development and the quantity and quality of soluble proteins in their grains, for breeding purposes. The experiment was conducted in a greenhouse, in a completely randomized experimental design, with the Paulistinha, BRS Novaera, Epace 10, and BR 17-Gurguéia cultivars. Leaf area, shoot fresh and dry matter, leaf protein content, number of nodules, and nodule and root dry matter were evaluated. In mature grains, soluble fractions and soluble amino acids were also quantified, and the electrophoretic analysis was performed with protein denaturation. There were no differences between cultivars for the plant development variables. However, protein quantity and quality in the grain differed between cultivars. 'BRS Novaera' and 'BR 17-Gurguéia' showed a higher soluble protein content in their grains. 'BRS Novaera' exhibited higher contents of two soluble sulfur amino acids - methionine and cysteine - , not differing from 'BR 17-Gurguéia' regarding methionine content. Both cultivars presented protein band polymorphism, but BRS Novaera had an extra band for albumins. The BRS Novaera and BR 17-Gurguéia cultivars have the highest content of soluble proteins in their grains and the greatest protein polymorphism, which makes them suitable for improving the nutritional quality of cowpea.

Kvalita zrna genotypov jarného jačmeňa pestovaných v agroekologických podmienkach Slovenskej a Bulharskej republiky

On two locations (Borovce, Slovak Republic and Karnobat, Republic of Bulgaria) 21 barley genotypes (Hordeum vulgare L.) were grown for two consecutive years (2017, 2018). Selected malting qualitative parameters were analysed in mature grains; the content of total starch, crude proteins, and β-D-glucan. The aim of the work was to analyse agro-ecological conditions affecting the content of selected quality parameters in the barley grain and to evaluate, select and exchange barley genotypes created with an added value in order to obtain suitable biological material usable in the changing environmental conditions of a country. The content of total starch in analysed samples was in the range 53.62% and 63.30%, crude proteins were between 11.50% and 15.46% and β-D-glucan was from 3.26% to 5.87%. Year, locality, genotype, and their interactions were factors affecting the content of all analysed parameters in the barley grain, however the content of proteins and β-D-glucan was relatively stable. In Slovak barley genotypes, higher levels of starch and lower levels of proteins and β-D-glucan were observed compared to Bulgarian genotypes. Higher amounts of starch were detected in the conditions of the Slovak Republic. In warmer conditions of the Republic of Bulgaria, higher amounts of proteins and β-D-glucan were observed. Statistically significant correlations (P≤0.05) were observed between total starch and crude proteins (r=-0.59) and between total starch and β-D-glucan (r=-0.40). The correlation between the content of proteins and β-D-glucan was positive (r=0.05), but in present experiment not statistically significant.

Lysine metabolism and amino acid profile in maize grains from plants subjected to cadmium exposure

In general, the effects of Cadmium (Cd) on crop quality are evaluated solely by Cd accumulation in the edible plant parts; thus, the potential effects on several nutritional features are not often taken into account. This study evaluated Cd effects on the enzymatic activities of lysine (Lys) metabolism, storage protein and amino acid profile in maize. Stress parameters were also assessed. In vegetative organs, Cd was accumulated in the following decreasing order: roots > stems > leaves. Cadmium accumulation in grains decreased at grain maturity (from 0.25 to 0.07 µg g–1 DW). In leaves, neither hydrogen peroxide content nor superoxide dismutase, catalase, ascorbate peroxide and guaiacol peroxidase activities did not change in Cd-treated plants compared to control plants. Lipid peroxidation was not detected in immature grains and leaves of plants under Cd exposure, indicating that Cd accumulation mainly in the roots is a mechanism to avoid oxidative stress in aboveground parts of the plant. However, Lys metabolism in immature grains was modified, showing increases in the specific activities of aspartate kinase (AK) and dihydrodipicolinate synthase (DHDPS) after Cd exposure. AK sensitivity to Lys feedback inhibition increased, but decreased in DHDPS in Cd-treated plants, suggesting differential regulation for these enzymes. In mature grains, the Lys content did not change, while the proline content increased by 54 % in Cd-treated plants. This is the first report on Cd effects on amino acid profile, storage protein contents and enzymes from Lys metabolism in grains of a cereal plant species.

Performance Evaluation and Adaptation of Food Barley (<i>Hordeum Vulgare</i> L.) Varieties in the Highlands of North Gondar Ethiopia

In Ethiopia, barley is also one of the oldest cultivated crops and currently it is the fifth most important cereal crop next to maize, tef, sorghum, and wheat and the study was conducted at Debark, Dabat and Wogera in 2014/15 main season with the objectives of identify high yielder food barley varieties using seven improved food barley varieties including local check in Randomized Complete Block Design with three replications. At Debark, the analysis of variance revealed highly significant difference (p≤0.01) among treatment means for days to heading, plant height and thousand seed weight. Significant difference at (p≤0.05) also observed among treatments for Maturity days, spike length, biomass and grain yield. The mean grain yield ranged from 3403kg/ha-5143kg/ha. Highest mean grain yield was recorded from variety HB-1307 (5143kg/ha), EH1493 (4636kg/ha) CROSS41/98 (4184kg/ha) and lowest mean grain yield was recorded from variety AGEGNEHU (3403kg/ha). At Dabat, the analysis of variance showed that significant difference (p≤0.05) for days to maturity, seeds per spike and thousand seed weight. The rest parameters exhibited non-significant difference among varieties. At Wogera, the analysis of variance showed highly significant difference at (p≤0.01) among tested varieties for days to maturity, spike length, seeds per spike, thousand seed weight and grain yield. Longest maturity days were recorded from variety CROSS-41/98 (124 days), while shortest maturity days were recorded from variety AGEGNEHU (112 days). The mean grain yield ranged from 2015kg/ha-5008kg/ha. At Wogera highest mean grain yield was recorded from variety HB-1307 (5008kg/ha) followed by CROSS41/98 (4416kg/ha). Over locations combined analysis of variances showed highly significant difference at (p≤0.01) among varieties for all yield and yield components except days to heading. The interaction of location by variety indicated that significant effect on biomass and grain yield. The rest yield components not affected by the interaction of genotype by location. Over location grain yield results ranged from 3641-4680 kg/ha. Lowest and highest grain yield were recorded on Local check (3641kg/ha) and HB-1307 (4680kg/ha), respectively. Therefore, HB-1307 and CROSS 41/98 recommended for seed production at highland areas of north Gondar and similar agro ecologies.

Effect of antimicrobial activity from fermented mature coconut water to sheath brown rot of rice disease

Rotting of grains or sheaths caused by Pseudomonas fuscovaginae is common for mature plants and grains of seedlings. This study explored the effect of antimicrobial activity from fermented mature coconut water to understand better a certain kind of rotting in sheaths of rice plants screened against the pathogen. Fermented matured coconut water was extracted with methanol solvent demonstrated the highest activity with 20.02 mm of inhibition followed by water solvent with 10.10 mm of inhibition. Both negative controls for methanol and water-based extracts showed no inhibition activities towards the pathogen. Methanol extraction was then determined for minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). The finding indicated that 20% (v/v) concentration was recorded as MIC and 30% (v/v) concentration as MBC for this pathogen to reduce the disease lesion length significantly (P < 0.05). The findings from this study will be useful for agriculture related agencies in controlling the disease for a higher productivity of rice production.

Identification of globulins in aleurone layers of wheat species in mature grain

Subject description: The aleurone layer is a living tissue that contains many bioactive compounds. This layer is rich up mostly of proteins, minerals and vitamins. Objective: this work makes it possible to search for sites carrying post-tradictional modifications on the sequences of three types of globulins identified that allow us to predict virtual reality. Results: The proteomic approach allowed us to identify numerous reserve proteins including three types of globulins (Glo3, Glo-3C, Glo3B) belonging to carbohydrate metabolism., 78% homology between Glo-3 and Glo-3 3B was found and 93% homology between Glo-3 and Glo-3C. Type 3B globulins are potentially three times more methylated, hydroxylated and much more ribosylated ADP than type 3 globulins. Type 3C globulins could be completely phosphorylated and five times more than type 3 and 3B globulins. They will then agree to confirm by chemical analysis and mass spectrometry this work.

Development of a Drink Type Infusion From Coffee Pulp (Arabia coffea) Lempira Variety of Honduras

This work aimed to develop an infusion type beverage from Lempira coffee pulp for human consumption. Samples from the Honduran Coffee Institute IHCAFE were used. According to the results obtained from the sensory analysis, it was determined that 70.75% of the evaluators prefer the beverage made with mature grains, given that a balance in taste and acidity is obtained. As for the mass concentration of the packaged content, 60% of the universe of tasters prefer a concentration of 1.6 g of dried pulp per cup. Regarding the type of grinding of the grain, it was determined that 80% of the tasters prefer coarse grinding (701 to 900 &amp;micro;m), describing it as an extremely pleasant product in its flavor and color, with shades of Jamaica, tamarind and nuts. Checking that with this particle size there is a greater release of flavors and maintains a balance in terms of aromas, however in fine particles (350 to 500 &amp;micro;m), their fragrances stand out, but negatively affects their taste and the high sedimentation rate. Therefore, it was concluded that the quality of the infusion drink from coffee pulp is influenced by the type of grinding used for its preparation.

Genetic dissection of zinc, iron, copper, manganese and phosphorus in wheat (Triticum aestivum L.) grain and rachis at two developmental stages

The development of high-yielding wheat genotypes containing micronutrient-dense grains are the main priorities of biofortification programs. At the International Maize and Wheat Improvement Center, breeders have successfully crossed high zinc progenitors including synthetic hexaploid wheat, T. dicoccum, T. spelta and landraces to generate high-zinc varieties. In this study, we report a genome-wide association using a wheat diversity panel to dissect the genetics controlling zinc, iron, copper, manganese and phosphorus concentrations in the grain and rachis during grain development and at physiological maturity.Significant marker-trait associations (MTAs) were identified for each nutrient using multi-locus mixed model methodologies. For mature grain, markers that showed significant pleiotropic effects were found on chromosomes 1A, 3B and 5B, of which those on chromosome 5B at ∼95.5 cM were consistent over two growing seasons. Co-located MTAs were identified for the nutrient concentrations in developing grain, rachis and mature grain on multiple chromosomes. The identified genomic regions included putative candidate genes involved in metal uptake and transport and storage protein processing. These findings add to our understanding of the genetics of the five important nutrients in wheat grain and provide information on genetic markers for selecting high micronutrient genotypes.

Exogenous application of zinc (Zn) at the heading stage regulates 2-acetyl-1-pyrroline (2-AP) biosynthesis in different fragrant rice genotypes

Zinc (Zn) is an important microelement for rice and plays a key role in many physiological processes. This study assessed the physio-biochemical responses involved in biosynthesis of 2-acety-1-pyrroline (2-AP), which is a key compound in the aroma of fragrant rice, in four different fragrant rice varieties, i.e., Meixiangzhan-2, Xiangyaxiangzhan, Ruanhuayou-134, and Yunjingyou. Four concentrations (0, 0.50, 1.00 and 2.00 g L−1) of zinc chloride were applied to fragrant rice foliage at the heading stage and named CK, Zn1, Zn2 and Zn3, respectively. Our results showed that compared with CK, the Zn1, Zn2 and Zn3 treatments all significantly increased the 2-AP concentration in mature grains of the four fragrant rice genotypes. Furthermore, exogenous application of Zn not only enhanced the activities of enzymes, including proline dehydrogenase (PDH), △1-pyrroline-5-carboxylic acid synthetase (P5CS), and diamine oxidase (DAO), which are involved in 2-AP biosynthesis, but also improved the contents of the related precursors, such as Δ1-pyrroline, proline and pyrroline-5-carboxylic acid (P5C). In addition, compared to the CK treatment, the Zn2 treatment markedly increased the net photosynthetic rate of fragrant rice during the grain filling stage and increased the seed-setting rate, 1000-grain weight and grain yield in all fragrant rice genotypes. Foliar application of Zn also markedly increased the grain Zn content. In general, 1.00 g L−1 seemed to be the most suitable application concentration because the highest 2-AP content and grain weight were recorded with this treatment.

Evaluation of early maturing promiscuous soybean varieties in the irrigated and the rain-fed areas of Sudan

Soybean (Glycine max (L.) Merr.) is relatively a new crop in Sudan. Limited number of improved varieties for commercial use requires the development of early maturing and high-yielding soybean varieties suiting the diverse agro-climatic zones of the country. Eight promising soybean varieties introduced from the International Institute of Tropical Agriculture (IITA) were evaluated at eight irrigated and rain fed environments at Wad Medani, Kenana, and Damazin from 2014 to 2016. The improved late maturing varieties Sudan1 and Sudan2 were used as checks. Trials were arranged in a randomized complete block design with four replicates. The highest grain yields were obtained for the checks Sudan1 (2400 kg ha−1) and Sudan2 (2330 kg ha−1); followed by the introduced varieties TGx 1972-11F (2160 kg ha−1) and TGx 1977-2F (2040 kg ha−1). However, TGx 1987-10F and TGx 1972-11F were earlier than the checks, at least 2-week differences in the 50% flowering and days to maturity. Comparing these two varieties with the checks, TGx 1972-11F and TGx 1977-2F had 1.00 and 0.99, 95% confidence interval, indicating that these two varieties had a good yield stability over environments. Grain yield was also positively correlated with fodder yield, plant height, pods plant−1, and harvest index. The high average grain yields and yield stability of TGx 1972-11F across environments, coupled with its early maturity and good grain quality, makes the TGx 1972-11F an excellent choice to be released for commercial use. This prompted the National Variety Release Committee of the country to release it under the name of “Soya4.”

Rapid identification and characterization of genetic loci for defective kernel in bread wheat

BackgroundWheat is a momentous crop and feeds billions of people in the world. The improvement of wheat yield is very important to ensure world food security. Normal development of grain is the essential guarantee for wheat yield formation. The genetic study of grain phenotype and identification of key genes for grain filling are of great significance upon dissecting the molecular mechanism of wheat grain morphogenesis and yield potential.ResultsHere we identified a pair of defective kernel (Dek) isogenic lines, BL31 and BL33, with plump and shrunken mature grains, respectively, and constructed a genetic population from the BL31/BL33 cross. Ten chromosomes had higher frequency of polymorphic single nucleotide polymorphism (SNP) markers between BL31 and BL33 using Wheat660K chip. Totally 783 simple sequence repeat (SSR) markers were chosen from the above chromosomes and 15 of these were integrated into two linkage groups using the genetic population. Genetic mapping identified three QTL, QDek.caas-3BS.1, QDek.caas-3BS.2 and QDek.caas-4AL, explaining 14.78–18.17%, 16.61–21.83% and 19.08–28.19% of phenotypic variances, respectively. Additionally, five polymorphic SNPs from Wheat660K were successfully converted into cleaved amplified polymorphic sequence (CAPS) markers and enriched the target regions of the above QTL. Biochemical analyses revealed that BL33 has significantly higher grain sucrose contents at filling stages and lower mature grain starch contents than BL31, indicating that the Dek QTL may be involved in carbohydrate metabolism. As such, the candidate genes for each QTL were predicated according to International Wheat Genome Sequence Consortium (IWGSC) RefSeq v1.0.ConclusionsThree major QTL for Dek were identified and their causal genes were predicted, laying a foundation to conduct fine mapping and dissect the regulatory mechanism underlying Dek trait in wheat.

Phenolic compounds and biological activities of rye (Secale cereale L.) grains

AbstractThe rye flour is, together with the wheat flour, the basic ingredient used in traditional bread baking. The rye grain contains many compounds with significant impacts on the consumer. Considering that, various biologically active phytochemicals were determined in extracts from mature grains of 19 rye genotypes (Secale cereale L.). The content of total phenols, flavonoids, phenolic acids and thiols, as well as antioxidant activities and inhibitory activities against trypsin, thrombin, and urokinase were analyzed by spectrophotometric methods. The vanillic acid, vanillin, p-coumaric acid, and t-ferulic acid were analyzed in particular by high performance liquid chromatography (HPLC). The observed differences in the amounts and activities between rye genotypes reflected variations in their genetic background. Rye grain is a remarkable source of specific phytochemicals. Genetic diversity in rye makes it possible to identify individual genotypes that have a unique content and biological activity of compounds deposited in mature grains. One subgroup of rye genotypes had higher values of antioxidant properties and concentrations of polyphenols. Other sub-group had higher proteinase inhibitory activities and contents of polyphenols. The third sub-group contained as though the universal genotypes, i.e. genotypes with average values in nearly all the measured parameters.

Probing the effect of a plus 1bp frameshift mutation in protein-DNA interface of domestication gene, NAMB1, in wheat

Transcription factor NAM-B1 has a major role in the process of senescence, which results in higher Fe and Zn concentrations in grains of wild wheat (T. durum; Td). The absence of the wild type NAMB1 in T. aestivum (Ta), one of the cardinal crops essential for more than 1/3rd of the global population, affects Fe and Zn remobilisation to the maturing grain from the flag leaf resulting in lesser micronutrient bioavailability. The cardinal difference in the NAMB1 gene between the two species is the absence of +1 bp allele in Ta. Insilico studies using NAMB1 from Td and Ta was performed to explore the variation in the interaction with the conserved cis-element DNA motif (CATGTG) as both the proteins share the same domain, but there are no in silico studies reported of these proteins. The secondary structure, 3D-modelling of the proteins, DNA-protein docking and dynamics have computed by Schrodinger Prime Suite. Predicted secondary structures were energy minimised using Macromodel and docking was performed based on binding energy and hydrogen bonds. Molecular dynamics simulation of NAMB1-Ta and NAMB1-Td individually and with the cis-element motif, performed for 100 ns, revealed significant variations in the protein-DNA interaction in Ta. This work provides the modelled 3D-interaction profile caused by a single bp frameshift mutation in understanding the difference in function between NAMB1 orthologs due to lack of NAC domain. The overall computational analysis reveals that NAMB1-Ta and NAMB1-Td proteins display a good amount of dissimilarity in their structure, dynamics and DNA-binding characteristics.Communicated by Ramaswamy H. Sarma

Sucrose Synthase Enhances Hull Size and Grain Weight by Regulating Cell Division and Starch Accumulation in Transgenic Rice.

Grain size and weight are two important determinants of grain yield in rice. Although overexpression of sucrose synthase (SUS) genes has led to several improvements on cellulose and starch-based traits in transgenic crops, little is reported about SUS enhancement of hull size and grain weight in rice. In this study, we selected transgenic rice plants that overexpressed OsSUS1-6 genes driven with the maize Ubi promoter. Compared to the controls (wild type and empty vector line), all independent OsSUS homozygous transgenic lines exhibited considerably increased grain yield and grain weights. Using the representative OsSUS3 overexpressed transgenic plants, four independent homozygous lines showed much raised cell numbers for larger hull sizes, consistent with their enhanced primary cell wall cellulose biosynthesis and postponed secondary wall synthesis. Accordingly, the OsSUS3 transgenic lines contained much larger endosperm volume and higher starch levels than those of the controls in the mature grains, leading to increased brown grain weights by 15–19%. Hence, the results have demonstrated that OsSUS overexpression could significantly improve hull size and grain weight by dynamically regulating cell division and starch accumulation in the transgenic rice.

Nitrogen applications made close to silking: Implications for yield formation in maize

Given the growing interest in late N applications made at vegetative stages just prior to silking (R1), there is a need to characterize how yield formation in maize responds when a small amount of N is applied early in the season, and the bulk of N fertilizer is delayed to vegetative stages close to R1. To understand how the development of kernel number (KN) and weight (KW) are affected by this shift in fertilizer N availability, a two-year split-plot experiment was conducted. The main plot factor consisted of five pre-plant N rates (in kg N ha−1: 0, 80, 140, 200, 260) and a split-plot factor consisted of an N application at V13, 9 or 11 days before R1. Split-plots either received no in-season N or a non-limiting N rate such that the total N applied equaled 260 kg N ha−1. At 0 kg N ha−1 pre-plant, N stress significantly reduced radiation use efficiency and crop growth rate during the critical period around R1, which in turn reduced potential kernel number (pKN) and potential kernel sink capacity (pKW) by the start of the linear phase of grain-fill. When 80 or 140 kg N ha-1 was applied pre-plant, N stress was not detected at or prior to the start of the linear phase of grain-fill, but reductions in KN and/or KW occurred later, within 30–40 days of R1. The V13 N application increased grain yield at the lower pre-plant N rates by either: i) preventing reductions in pKN and pKW at the start of the linear grain-fill period or by ii) better maintaining KN and KW during the linear phase of grain-fill. At maturity grain yield in the split-N treatments receiving 260 kg N ha−1 at V13 was statistically similar to 260 kg N ha−1 applied pre-plant, but maize N uptake increased in response to the V13 N application only once the crop became N deficient. Overall, these results provide a physiological understanding of the impact of late N applications on yield formation in maize and can assist in the further development of N management strategies that better synchronize fertilizer N supply with crop N demand.

Remote sensing techniques and stable isotopes as phenotyping tools to assess wheat yield performance: Effects of growing temperature and vernalization

This study compares distinct phenotypic approaches to assess wheat performance under different growing temperatures and vernalization needs. A set of 38 (winter and facultative) wheat cultivars were planted in Valladolid (Spain) under irrigation and two contrasting planting dates: normal (late autumn), and late (late winter). The late plating trial exhibited a 1.5 °C increase in average crop temperature. Measurements with different remote sensing techniques were performed at heading and grain filling, as well as carbon isotope composition (δ13C) and nitrogen content analysis. Multispectral and RGB vegetation indices and canopy temperature related better to grain yield (GY) across the whole set of genotypes in the normal compared with the late planting, with indices (such as the RGB indices Hue, a* and the spectral indices NDVI, EVI and CCI) measured at grain filling performing the best. Aerially assessed remote sensing indices only performed better than ground-acquired ones at heading. Nitrogen content and δ13C correlated with GY at both planting dates. Correlations within winter and facultative genotypes were much weaker, particularly in the facultative subset. For both planting dates, the best GY prediction models were achieved when combining remote sensing indices with δ13C and nitrogen of mature grains. Implications for phenotyping in the context of increasing temperatures are further discussed.