Durum Wheat Grain Research Articles

Determination of genetic parameters for inheritance of grain protein content in durum wheat

The aim of the study is to determine the genetic architecture and heritability of a basic quantitative trait related to grain quality of durum wheat. For this purpose, a half diallel cross was made in the period 2014–2016. Five modern durum wheat varieties were crossed to produce hybrid combinations. The testing period allowed for the cultivation of three F1 and two F2 generations. Parents and hybrids were grown under field conditions in three replications using a randomized block method. Protein content in the grain was measured by the standard method for its determination. The mean values of the trait have been statistically processed, and this has provided useful information for improving the quality of durum wheat grain. The heritability of the trait is influenced by additive variance and the dominant parameters. The larger dominant parameters determine that dominance plays a major role in the trait expression. This is also evidenced by manifestations of dominance and overdominance. In our cases, the selected parents contain more dominant genes in their genotype. The values of the trait increase with the accumulation of recessive genes. The varieties Victoria and Predel have more recessive genes in most cases than other tested parents. The heritability of the trait is mainly influenced by simple additive-dominant genetic system, but under certain conditions the presence of complementary epistasis is possible. Heritability coefficients indicate that effective selection of a genotype by phenotype is possible, but it should start in later segregated generations.

Non-Starch Polysaccharides in Durum Wheat: A Review.

Durum wheat is one of most important cereal crops that serves as a staple dietary component for humans and domestic animals. It provides antioxidants, proteins, minerals and dietary fibre, which have beneficial properties for humans, especially as related to the health of gut microbiota. Dietary fibre is defined as carbohydrate polymers that are non-digestible in the small intestine. However, this dietary component can be digested by microorganisms in the large intestine and imparts physiological benefits at daily intake levels of 30–35 g. Dietary fibre in cereal grains largely comprises cell wall polymers and includes insoluble (cellulose, part of the hemicellulose component and lignin) and soluble (arabinoxylans and (1,3;1,4)-β-glucans) fibre. More specifically, certain components provide immunomodulatory and cholesterol lowering activity, faecal bulking effects, enhanced absorption of certain minerals, prebiotic effects and, through these effects, reduce the risk of type II diabetes, cardiovascular disease and colorectal cancer. Thus, dietary fibre is attracting increasing interest from cereal processors, producers and consumers. Compared with other components of the durum wheat grain, fibre components have not been studied extensively. Here, we have summarised the current status of knowledge on the genetic control of arabinoxylan and (1,3;1,4)-β-glucan synthesis and accumulation in durum wheat grain. Indeed, the recent results obtained in durum wheat open the way for the improvement of these important cereal quality parameters.

Cultivation Area Affects the Presence of Fungal Communities and Secondary Metabolites in Italian Durum Wheat Grains.

In this study, durum wheat kernels harvested in three climatically different Italian cultivation areas (Emilia Romagna, Umbria and Sardinia) in 2015, were analyzed with a combination of different isolation methods to determine their fungal communities, with a focus on Fusarium head blight (FHB) complex composition, and to detect fungal secondary metabolites in the grains. The genus Alternaria was the main component of durum wheat mycobiota in all investigated regions, with the Central Italian cultivation area showing the highest incidence of this fungal genus and of its secondary metabolites. Fusarium was the second most prevalent genus of the fungal community in all cultivation environments, even if regional differences in species composition were detected. In particular, Northern areas showed the highest Fusarium incidence, followed by Central and then Southern cultivation areas. Focusing on the FHB complex, a predominance of Fusarium poae, in particular in Northern and Central cultivation areas, was found. Fusarium graminearum, in the analyzed year, was mainly detected in Emilia Romagna. Because of the highest Fusarium incidence, durum wheat harvested in the Northern cultivation area showed the highest presence of Fusarium secondary metabolites. These results show that durum wheat cultivated in Northern Italy may be subject to a higher FHB infection risk and to Fusarium mycotoxins accumulation.

Durum wheat grain and pasta from locally-grown crops: a case-study on Saragolla (Triticum turgidum ssp. turanicum) and Senatore Cappelli (Triticum turgidum ssp. durum) wheats

The ancient grains Senatore Cappelli and Saragolla are often used as raw material, generally in mixture, for the production of pasta, which represents one of the most consumed foods in Italy. Due to the wide employment of these wheats in cereal based foods, it was found interesting to get information on the nutritional value of food as widespread as pasta made by means of such wheats. In this study, long and short pasta samples produced from Saragolla and Senatore Cappelli were considered. Proximate chemical composition, starch digestibility and antioxidant compounds as well as cooking properties were studied. When the optimum cooking time is applied, pasta presents good sensory characteristics also thanks to the high protein content of raw material. Moreover, the employment of the durum whole meal in the pasta production, also guarantees a good level of bioactive compounds such as phenolic compounds.

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.

Management of common root rot and Fusarium foot rot of wheat using Brassica carinata break crop green manure

Brassica crop rotations have been associated with the reduction of pathogens, due to both the production of volatile sulfur compounds and changes in soil microbial community composition. In this research Brassica carinata, as break crop green manure, was evaluated for the control of common root rot and Fusarium foot rot of durum wheat in a complete randomized experimental scheme. Field trials were performed on seven farms, in some of the most representative areas of cereal production in Sicily, from 2011 to 2013. A total eradication of Bipolaris sorokiniana and Microdochium nivale populations following the B. carinata break crop, as compared to wheat monoculture, was found in all experimental fields. Fusarium culmorum population reduction ranged between 90% and 66%, with an average of 82% considering all field trials data. Symptoms or signs of common root rot were absent on wheat plants grown after the B. carinata break crop but were detectable on the wheat monoculture. Both incidence and severity of Fusarium foot rot were also reduced, by an average of 40.6% and 56.3%, respectively, following the B. carinata break crop in six of the seven field trials. After B. carinata break crop, wheat plant growth showed significant increases in height and weight, with an average increase of 48.3% and 49.0% respectively. Durum wheat grain yield was also significantly greater following the Brassica green manure, with increases ranging from 9.5% to 62.2%, as compared to wheat monoculture. B. carinata break crop green manure was also characterized by interesting results in terms of disease management in comparison to controls. These results suggest that the use of Brassicas such as B. carinata, as a break crop green manure, may potentially provide significant reduction of pathogens and disease development as well as improvement in grain yield of the succeeding crop.

Black point in spring durum wheat under different environmental conditions

The study of cereal seed mycocenosis is relevant in solving problems determining the production of healthy, environmentally friendly agricultural products. Black point of wheat grain is a disorder characterised by a brown-black discolouration at the embryo end of the kernel. It is found in all regions of durum wheat cultivation and it results in significant economic loss annually. We studied seven varieties of spring durum wheat that were grown in 2014-2019. The weather conditions of the growing season have a significant impact on the development of black point of durum wheat in the forest-steppe zone of the Altai Territory of Russia (South-Western Siberia). The defeat of seeds by a black point varied from 2.3% to 28.0% on average for varieties. To obtain high-quality grain that is not affected by this disease, phytosanitary measures are required that reduce the infection of seeds with phytopathogens and limit the development of the disease during the growing season. Analysis of the pathogenic composition of fungal microorganisms in seeds of spring durum wheat, formed in different vegetations, revealed the presence of representatives of Fusarium, Alternaria, Helminthosporium, Penicillium and Aspergillum with a predominance of the first 3 genera. We found the negative effect of Fusarium fungi on seed germination. In the field conditions of the forest-steppe of the Altai Territory, the development of a black point in durum wheat grain is determined by the colonization of seeds with Bipolaris sorokiniana. No correlation was found between the incidence of black point and the infection of seeds by Fusarium and Alternaria.

Carotenoid Pigment Content in Durum Wheat (Triticum turgidum L. var durum): An Overview of Quantitative Trait Loci and Candidate Genes.

Carotenoid pigment content is an important quality trait as it confers a natural bright yellow color to pasta preferred by consumers (whiteness vs. yellowness) and nutrients, such as provitamin A and antioxidants, essential for human diet. The main goal of the present review is to summarize the knowledge about the genetic regulation of the accumulation of pigment content in durum wheat grain and describe the genetic improvements obtained by using breeding approaches in the last two decades. Although carotenoid pigment content is a quantitative character regulated by various genes with additive effects, its high heritability has facilitated the durum breeding progress for this quality trait. Mapping research for yellow index and yellow pigment content has identified quantitative trait loci (QTL) on all wheat chromosomes. The major QTL, accounting for up to 60%, were mapped on 7L homoeologous chromosome arms, and they are explained by allelic variations of the phytoene synthase (PSY) genes. Minor QTL were detected on all chromosomes and associated to significant molecular markers, indicating the complexity of the trait. Despite there being currently a better knowledge of the mechanisms controlling carotenoid content and composition, there are gaps that require further investigation and bridging to better understand the genetic architecture of this important trait. The development and the utilization of molecular markers in marker-assisted selection (MAS) programs for improving grain quality have been reviewed and discussed.

Cadmium allocation to grains in durum wheat exposed to low Cd concentrations in hydroponics

This study aims to characterize the response of durum wheat to different concentrations of Cd found in agricultural soils. One French durum wheat cultivar (i.e. Sculptur) was exposed to low concentrations of Cd (5 nM or 100 nM) in hydroponics. After anthesis, the plants were fed with a solution enriched with the stable isotope 111Cd to trace the newly absorbed Cd. Plants were sampled at anthesis and grain maturity to assess how plant growth, Cd uptake and partitioning among organs, as well as Cd remobilization, differed between the two Cd exposure levels. Durum wheat did not show any visual symptoms of Cd toxicity, regardless of which Cd treatment was applied. However, post-anthesis durum wheat growth was 14% penalized at 100 nM due to the large transpiration-based accumulation of Cd in leaves at this stage. The allocation of Cd to the grains was not restricted but enhanced at 100 nM compared to 5 nM. Both the root-to-shoot Cd translocation and the fraction of aboveground Cd allocated to grains were higher in plants exposed to 100 nM. Cadmium was remobilized exclusively from roots and stems, and remobilized Cd contributed on average to 40–45% of the Cd accumulated in mature grains, regardless of which Cd treatment was applied. The relevance of these results to decreasing the concentration of Cd in durum wheat grains is discussed.

Effect of allele combinations at Ppd-1 loci on durum wheat grain filling at contrasting latitudes.

Flowering time is the most critical developmental stage in wheat, as it determines environmental conditions during grain filling. Thirty‐five spring durum genotypes carrying all known allele variants at Ppd‐1 loci were evaluated in fully irrigated field experiments for three years at latitudes of 41°N (Spain), 27°N (northern Mexico) and 19°N (southern Mexico). Relationships between weight of central grains of main spikes (W) and thermal time from flowering to maturity were described by a logistic equation. Differences in flowering time between the allele combination causing the earliest (GS100/Ppd‐B1a) and the latest (Ppd‐A1b/Ppd‐B1a) flowering were 7, 20 and 18 days in Spain, northern Mexico and southern Mexico, respectively. Flowering delay drastically reduced the mean grain filling rate (R) and W at all sites. At autumn‐sowing sites, an increase of 1°C in mean temperature during the first half of the grain filling period decreased W by 5.2 mg per grain. At these sites, W was strongly dependent on R. At the spring‐sowing site (southern Mexico), W depended on both R and grain filling duration. Our results suggest that incorporating the allele combinations GS100/Ppd‐B1a and GS105/Ppd‐B1a (alleles conferring photoperiod insensitivity) in newly released varieties can reduce the negative effects of climate change on grain filling at the studied latitudes.

Arbuscular mycorrhizal fungal inoculation and soil zinc fertilisation affect the productivity and the bioavailability of zinc and iron in durum wheat.

There is a growing recognition of the role of arbuscular mycorrhizal fungi (AMF) in food security, specifically the potential for AMF to enhance the yield and mineral nutrition-including phosphorus, zinc (Zn), and iron (Fe)-of food crops. However, the bioavailability of Zn and Fe for humans in the grain of cereal crops can be overestimated by failing to consider the abundance of phytic acid (PA). This is because PA can chelate the micronutrients, making them difficult to absorb. In order to understand the effect of an AM fungus and soil Zn concentration on the productivity and nutritional quality of food parts, this study examined the growth and nutritional responses of durum wheat, with and without inoculation with Rhizophagus irregularis, at five soil Zn concentrations. Growth and nutrient responses of the plants to soil Zn amendment was stronger than responses to AMF. However, the protective effect of AMF under soil Zn toxicity conditions was observed as reduced Zn concentration in the mycorrhizal durum wheat grain at Zn50. Here, AMF inoculation increased the concentration of PA in durum wheat grain but had no effect on the concentration of Zn and Fe; this consequently reduced the predicted bioavailability of grain Zn and Fe, which could lead to a decrease in nutritional quality of the grain. This research suggests that in soil with low (available) phosphorus and Zn concentrations, AMF may reduce the food quality of durum wheat because of an increase in PA concentration, and thus, a decrease in the bioavailability of Zn and Fe.

Cd concentration of durum wheat grain as influenced by soil salinity

Cadmium (Cd) accumulation in plant tissues has recently gained a worldwide-growing concern due to food safety and health care. Soil salinity is an important causal agent influencing Cd accumulation in cereal grains and durum wheat is known as the most sensitive to Cd toxicity among cereals. This research is aimed at evaluating influence of soil salinity on cadmium accumulation in durum wheat grain. Influence of NaCl doses (0, 200 and 1000 mg kg -1 ) on Cd concentration in durum wheat grain ( Triticum turgidum L. durum ) grown in soils treated with Cd (0 and 1.0 mg kg -1 ) was established. Grain Cd concentration in control plants (without Cd and NaCl) was 21 µg kg -1 , while 200 and 1000 mg kg -1 NaCl doses resulted in 60 and 75 µg kg -1 Cd with 300% and 400% increase, respectively. Grain Cd concentration in Cd-treated soil arose from 1325 µg kg -1 in the control plants to 1778 and 2411 µg kg -1 in the plants exposed to 200 and 1000 mg kg -1 NaCl, respectively. The present study reveals that soil salinity increases Cd accumulation in grain even if soil Cd level is very low. Further, cadmium is transported to grain easily and soil salinity enhances such carriage in Cd-contaminated soils .

How do conventional and organic management affect the healthy potential of durum wheat grain and semolina pasta traits?

The effect of cropping system (conventional vs. organic) and soil tillage (conventional vs. reduced tillage) on the health potential of durum wheat grain as well as on semolina and pasta quality traits was investigated in a long-term field experiment. Total antioxidant capacity, total arabinoxylans, alkylresorcinols, yellow pigments and total phenolics, which were assessed in kernels, revealed differences between the two cultivation systems only in 2011, whereas in the 2010 rainy season, cropping management did not influence these compounds. Proteins and W index were higher in the conventional system, except for the exceptionally rainy years. In contrast, the quality of cooked spaghetti was comparable in both management systems. Soil tillage differently affected bioactive compounds but had no impact on semolina and pasta quality. Overall, climatic conditions was the major factor affecting the quality of durum wheat. Our results indicate that an organic system does not represent a constraint to obtaining durum wheat grain with healthy potential relative to conventional wheat.

СОЗРЕВАНИЕ ЗЕРНА ЯРОВОЙ ТВЁРДОЙ ПШЕНИЦЫ В СВЯЗИ С ПОГОДНЫМИ ФАКТОРАМИ И ПРИЁМАМИ АГРОТЕХНИКИ В ОРЕНБУРГСКОМ ПРИУРАЛЬЕ

The aim of the study is to increase the yield of spring durum wheat in the Orenburg Urals. Spring hard wheat makes more demands on the temperature region during the formation and filling of grain. Due to the growing aridity conditions of the second half of the growing season, when the grain falls asleep, have become more unfavorable. As you know, the nature of the filling, favorable weather conditions in this period are determined by the yield and quality of grain. The studies were carried out in 2016-2018 in the Central zone of the Orenburg region on chernozems ordinary in two stages of the main tillage. Weather conditions contrasted sharply. The research method is a field experiment. Experience and research were conducted according to conventional methods. Analysis of the grain samples was performed using a laboratory balance Adam NSV 602N and furnace SESH-3M. Mathematical analysis was performed in the program Statistica 6.0. It is established that the duration of grain loading in the study area depends on the weather conditions of the year, ranging from 20-21 days to 31 days. The growth rate of dry matter accumulation in durum wheat grain is observed in the air temperature range 18.7-26.2°C, followed by an increase in temperature reduces the increase. Amid the subsurface processing plowed fields, reducing grain moisture is less intense: 10 grade Orenburg-plowing is of 0.99 – 2.46% on a day, subsurface tillage-0.80 – 2.50% daily; cultivar bezenchukskaya 210 – plowing 1.64-of 2.34%, subsurface tillage-1.03-2.32%.

Factors Affecting the Storage Grain Protein Content of Tetraploid Wheat (Triticum turgidum L.) and Their Management

This review work aims to evaluate the factors affecting the storage grain protein content of tetraploid Wheat (Triticum turgidum L.) and their management. For commercial production of tetraploid wheat, grain protein content is considered very important. As the grain receive great market attention due to protein premium price paid for farmers, mainly above 13% that will give about 12% of protein in the milled semolina. However, this review state that grain protein content of tetraploid wheat is sensitive to environmental conditions prevailing before and during grain filling, crop genetics and cultural practices. This and associated problems universally call agronomic based alternative solution to ameliorate protein concentration in durum wheat grain. This could be modified through manipulating seeding rates, selection crop varieties, adjusting nitrogen amount and fertilization time and sowing date. The decision of time of nitrogen application however should be made based on the interest of the farmers. If the interest gears towards grain yield, apply nitrogen early in the season and apply the fertilizer later if heading for better protein concentration.

Breeding and genetic approaches to the estimation of quality prospects of winter durum wheat hybrids

One of the main requirements for the quality of winter durum wheat grain is the development of varieties with tough elastic gluten. The breeding process in this direction will be more successful if the assessment of the trait is known at the early stages. In our study SDS-sedimentation was used for such an assessment. In addition to assessing the quantitative severity of the SDS-sediment index, the breeder should be aware of the efficiency of high-quality progeny selection in generations of hybrids, the prospects of the population, the breeding value of the initial components involved in hybridization. In this regard, the main purpose of the conducted research is to reveal the efficiency of selection for the gluten quality from SDS-sedimentation in hybrid populations (F 2 – F 4 ) of winter durum wheat using breeding and genetic parameters. There have been presented the study results of 14 hybrid combinations of winter durum wheat obtained from crossing of the varieties with different or equal amount of sediment. It was shown that the response of hybrid populations (F 2 – F 4 ) to the selection of high-qualitative genotypes with different intensities was ambiguous, and in most combinations it was low or absent. The realized heritability in the groups of selection greatly varied depending on the severity of the selection; on the parental forms taken for hybridization; on the environmental conditions during the grain formation and ripening. There were identified such promising hybrid populations as “Kremona” × “Kurant”, “Terra” × “Kremona”, “Kremona” × “Terra”, “Zolotko” × “Aksinit”, “Zolotko” × “Kremona” in which the genotypic shift and realized heritability are revealed in all generations and selective groups.

Effects of Stem Rust (<i>Puccinia graminis</i> f.sp. <i>tritici</i>) on Yield, Physical and Chemical Quality of Durum Wheat Varieties in East Shoa Zone, Ethiopia

Stem rust or black rust caused by <i>Puccinia graminis</i> f.sp. <i>tritici</i> is one of the major biotic constraints of wheat production in Ethiopia. The disease may cause substantial quantitative and qualitative yield losses but much of the work in Ethiopia on this pathosystem focuses on quantitative yield loss and qualitative losses are often overlooked. As the result, the current research was designed with the objective of elucidating the effect of wheat stem rust on yield, physical and processing quality of durum wheat. For this purpose, a factorial field experiment involving three durum wheat varieties (Ude, Denbi and Hitosa) were selected and Tilt application was conducted at Debre Zeit Agricultural Research Centre for two cropping seasons (2016-2017). The experiment was laid out in randomized complete block design with three replications and untreated checks were included for comparison purpose. Results revealed significant variations in disease parameters and crop performance of treated plots, wheat varieties and their interactions. Stem rust severity was significantly reduced by the application of Tilt across all wheat varieties, and the highest decrease in disease level (8.9 and 15.2%) was achieved by Tilt application in 2017 and 2016 cropping seasons, respectively. Correlation analysis revealed negative relationship between stem rust and durum wheat grain yield and quality parameters, which was highly significant in most cases. However, there was highly significantly positive correlation (r=0.31** and r = 0.39***) between stem rust and grain protein content during the year of 2016 and 2017 cropping seasons, respectively. The results confirmed the economic importance of stem rust to food industry for its effect on grain yield, physical and processing quality of durum wheat in Ethiopia.

Quality of spring wheat grain at cultivating with modern technologies

The results of studies in the grain-crop rotation (2011-2017 years) to study the impact of direct seeding technologies on the quality of grain and the efficiency of spring durum wheat cultivation on the chernozems of the middle Volga region are presented. Grain of spring durum wheat is impractical to use for feed purposes, while in the Volga region has not been studied the effect of direct sowing with different levels of intensity on the quality of grain. Favorable weather conditions for the growth and development of culture established in 2017 (SCC for may-August= 0.94). In other years, the SCC was at and below the average annual values (0.45-0.74). Complex application of fertilizers and plant protection products providing the same productivity and quality of grain, in comparison with the intensive background of traditional technology, contributed to an increase in conditional net income and profitability by 1534.3-1902.7 rubles/ha and 34.3-34.4%, respectively. Compared with traditional technology without the use of fertilizers and insecticides, the advantage of the best options increased to 3826.4-4184.3 rubles/ha and 47.0-47.1 %. The indicators of grain quality significantly influenced the SCC vegetation period of culture. Improved water availability of crops contributed to the increase in weight of 1000 seeds from 36.3-36.9 g to 42.8-44.9 g and reduce the nature of grain from 782.0-791.8 g/l to 750.9-767.9 g/l (1.8-5.4 %). The highest protein content was found in dry years – 15.4-16.3 %, which is 1.1-3.5 % more than in wet years. On the basis of the conducted research to improve the efficiency and quality of grain at the level of the required indicators, the technology of direct sowing with complex application of plant protection against pests and weeds, pre-sowing application of nitrogen fertilizers N30 is proposed.

Identification of Lycopene epsilon cyclase (LCYE) gene mutants to potentially increase β-carotene content in durum wheat (Triticum turgidum L.ssp. durum) through TILLING.

Increasing β-carotene (a vitamin A precursor) content in Triticum turgidum L. ssp. durum (durum wheat) grains is important to improve pasta nutritional quality. Studies in other species show that altering the expression of LCYE genes increases the flux towards the β-β branch, accumulating higher β-carotene levels. Durum wheat is a tetraploid species that has two LCYE genes (LCYE-A and LCYE-B) associated to the A and B genomes. The objective of this work was to produce durum wheat LCYE mutants through EMS to potentially increase β-carotene content. The LCYE point mutations created with EMS were identified using a Kronos TILLING (Targeting Induced Local Lesion IN Genomes) mutant population. Specific primers that amplified exons 3 through 10 of the LCYE genes were designed and validated. To simplify the TILLING procedure, fragments were digested with CJE (Celery Juice Extract) and visualized on 2% agarose gels. 6X mutant pools were identified, which showed cleavage products and then made into 2X pools to identify mutant individuals. LCYE mutants were then sequenced and evaluated with BLOSUM62, SIFT and PSSM algorithms. Mutants with substitutions W437*, P334L and G368R in LCYE-A and P405L, G352R and T393I in LCYE-B predicted to affect protein function were selected. Substitution W437* increased β-carotene in 75% and overall total carotenoids content in leaves of the mutant 2426 (A1 mutant line), but no significant differences relative to the control were found in grains through HPLC. Finally, the increased levels of β-carotene on leaves have potential applications to improving plant resistance under contaminated environmental conditions.

Thermal, physical and morphological properties of durum wheat

The aim of this study was to evaluate selected physical, morphological and thermal properties of durum wheat grain. Additionally, the parameters of control grain (grown without fertilizers or a growth retardant) were compared with the grain from treatments with different combinations of nitrogen fertilizer and growth retardant. The grain of durum wheat grown without nitrogen fertilizer or growth retardant was characterized by the lowest values of thousand-kernel weight (47.24 g for the sample collected in 2015 and 45.70 g for the sample collected in 2016), bulk density (814 kg m−3—2015 and 745 kg m−3—2016), length (7.62 mm—2015 and 7.54 mm—2016), width (3.35 mm—2015 and 3.32 mm—2016) and shape factors (specific perimeter of object boundary, Danielsson coefficient). The highest values of thousand-kernel weight, bulk density and width of durum wheat grain harvested in both years of the study were determined in the samples collected in the treatment with a total nitrogen rate of 80 kg ha−1 without the growth retardant. In the samples collected in 2015, the above combination produced grain with the greatest length, the highest specific perimeter of object boundary and the highest Danielsson coefficient. In 2016, these parameters were highest in grain from the treatment where a total nitrogen rate of 80 kg ha−1 was combined with a growth retardant. Different combinations of nitrogen fertilization and the growth retardant did not affect the true density or the thermal properties of wheat grain. Statistically significant differences between the experimental groups were not observed.