Influence of different irrigation and nitrogen levels on crude oil and fatty acid composition of maize (

Genome-wide association studies of grain yield and quality traits under optimum and low-nitrogen stress in tropical maize (Zea mays L.)

Genome-wide association study (GWAS) demonstrated that multiple genomic regions influence grain quality traits under nitrogen-starved soils. Using genomic prediction, genetic gains can be improved through selection for grain quality traits. Soils in sub-Saharan Africa are nitrogen deficient due to low fertilizer use and inadequate soil fertility management practices. This has resulted in a significant yield gap for the major staple crop maize, which is undermining nutritional security and livelihood sustainability across the region. Dissecting the genetic basis of grain protein, starch and oil content under nitrogen-starved soils can increase our understanding of the governing genetic systems and improve the efficacy of future breeding schemes. An association mapping panel of 410 inbred lines and four bi-parental populations were evaluated in field trials in Kenya and South Africa under optimum and low nitrogen conditions and genotyped with 259,798 SNP markers. Genetic correlations demonstrated that these populations may be utilized to select higher performing lines under low nitrogen stress. Furthermore, genotypic, environmental and GxE variations in nitrogen-starved soils were found to be significant for oil content. Broad sense heritabilities ranged from moderate (0.18) to high (0.86). Under low nitrogen stress, GWAS identified 42 SNPs linked to grain quality traits. These significant SNPs were associated with 51 putative candidate genes. Linkage mapping identified multiple QTLs for the grain quality traits. Under low nitrogen conditions, average prediction accuracies across the studied genotypes were higher for oil content (0.78) and lower for grain yield (0.08). Our findings indicate that grain quality traits are polygenic and that using genomic selection in maize breeding can improve genetic gain. Furthermore, the identified genomic regions and SNP markers can be utilized for selection to improve maize grain quality traits.

Kernel characterization and starch morphology in five varieties of Peruvian Andean maize

Peruvian Andean maize (PAM) has been commonly used as an ingredient that confers color, flavor, and texture in culinary. Nevertheless, no studies are focusing on agro-industrial interest characteristics to develop new products. This study aimed to evaluate the physicochemical, nutritional, and technological characteristics of kernels and the starch granule morphology of the five main PAM varieties: Chullpi, Piscorunto, Giant Cuzco, Sacsa, and Purple. PAM's characterization was performed according to the official methods, and its morphology was observed by scanning electron microscopy (SEM). Physically, the varieties of larger kernels (Giant Cuzco and Sacsa) presented a higher 1000-kernel weight and a lower hectoliter weight than those of smaller size (Piscorunto, Purple, and Chullpi). Nutritionally, PAM had higher ether extract (5%) and ash (2%) contents than other pigmented maizes. Likewise, they presented more significant amounts of essential amino acids, as leucine (10 mg/g protein) and tryptophan (up to 2 mg/g protein); unsaturated fatty acids, oleic (30%) and linoleic (53%); and minerals, as magnesium (104 mg/100 g). SEM showed that endosperm structure and starch morphology vary according to maize types and their grain location. Starch granules of floury PAM varieties were small and polyhedral in the sub-aleurone endosperm, whereas those of the central area were bigger and spherical. In Chullpi, it was observed a portion of vitreous endosperm with a compact structure. The low protein content (8.3%) and the endosperm structure of floury varieties of PAM influenced their pasting properties. Their pasting temperature was <69 to 71 °C>, peak viscosity < 3200 to 4400 cP>, and seatback <1250 to 1706 cP>; therefore, they do not retrograde easily. The results suggest that PAM has characteristics that would help elaborate regional products with added value, such as soups, willows, beverages, and porridges.

Korean Maize Hybrids Present Significant Diversity in Fatty Acid Composition: An Investigation to Identify PUFA-Rich Hybrids for a Healthy Diet

Precise information on the content and composition of nutritionally essential metabolites in food crops is a prerequisite for dietary recommendations and nutrient-dense food formulations. In the present study, the fatty acid profile of 21 Korean maize hybrids was analyzed by gas chromatography (GC)–mass spectrometry (MS). In the studied hybrids, linoleic acid (LA; C18:2n6c) was dominant (38.0–58.9%), followed by oleic (OA; C18:1n9c) (23.5–45.3%), palmitic (C16:0) (10.8–17.3%), and stearic acids (C18:0) (1.84–3.86%). Among all the quantified fatty acids, the highest variation was recorded for LA and OA. The highest amount of LA (58.9%), the lowest amount of OA (23.5%), and the highest polyunsaturated fatty acids (PUFAs)/monounsaturated fatty acids (MUFAs) ratio of 2.47 were recorded in the Shingwang hybrid. The highest PUFAs/saturated fatty acids (SFAs) ratio of 4.04 was recorded in the Ahndaok hybrid due to the high content of LA (57.8%) and low amount of SFA. Similarly, the highest PUFAs + MUFAs/SFAs ratio of 6.38 was recorded in the Pyeonggangok hybrid as a result of the high OA (34.6%) and LA (51.4%) contents, along with the lowest amount of SFAs. Considering the high levels of health-beneficial MUFAs and PUFAs and low levels of undesirable SFAs, the maize hybrids Pyeonggangok, Ahndaok, and Shingwang can be used in the preparation of a healthy PUFA-rich diet.

Nitrogen availability and genotype affect major nutritional quality parameters of tef grain grown under irrigation

Worldwide demand for tef (Eragrostis tef) as a functional food for human consumption is increasing, thanks to its nutritional benefits and gluten-free properties. As a result, tef in now grown outside its native environment in Ethiopia and thus information is required regarding plant nutrition demands in these areas, as well as resulting grain health-related composition. In the current work, two tef genotypes were grown in Israel under irrigation in two platforms, plots in the field and pots in a greenhouse, with four and five nitrogen treatments, respectively. Nutritional and health-related quality traits were analyzed, including mineral content, fatty acid composition, hydrophilic and lipophilic antioxidative capacity, total phenolic content and basic polyphenolic profile. Our results show that tef genotypes differ in their nutritional composition, e.g. higher phenolic contents in the brown compared to the white genotype. Additionally, nitrogen availability positively affected grain fatty acid composition and iron levels in both experiments, while negatively affecting total phenolics in the field trials. To conclude, nitrogen fertilization is crucial for crop growth and productivity, however it also implicates nutritional value of the grains as food. These effects should be considered when fertilizing tef with nitrogen, to optimize both crop productivity and nutritional effects.

Macronutrients influence yield and oil quality of hybrid maize (Zea mays L.)

In the present two-year study, an attempt was made to estimate the grain yield, grain nutrient uptake, and oil quality of three commonly grown maize (Zea mays L.) hybrids fertilized with varied levels of nitrogen (N), phosphorus (P) and potassium (K). Results obtained from both the experimental years indicated that application of 125% of recommended dose of fertilizer (RDF) recorded maximum grain yield (10.37 t ha-1; 124% higher than control). When compared with 100% RDF, grain yield reduction with nutrient omission was 44% for N omission, 17% for P omission, and 27% for K omission. Nitrogen uptake was increased with increasing NPK levels up to 150% RDF that was statistically at par (p ≥ 0.01) with 125% RDF. Increasing trend in P and K uptake was observed with successive increase in NPK levels up to 125% RDF, above which it declined. The protein content was significantly higher in grains of var. P 3396 with 125% RDF. Nutrient management has significant (p ≤ 0.01) role in the grain oil content. Saturated fatty acids (palmitic, stearic and arachidic acid) content decreased, and unsaturated fatty acid (oleic, linoleic and linolenic acid) increased with increasing NPK levels. The average oleic acid desaturation and linoleic acid desaturation ratios were increased with increasing NPK levels up to 100 and 125% RDF, respectively. However, average monounsaturated fatty acids (MUFA): poly-unsaturated fatty acids (PUFA), saturated: unsaturated as well as linoleic: linolenic acid ratios were increased on receiving 75% RDF, and beyond that it showed decreasing trend. The omission of K had the highest inhibitory effect on corn oil quality followed by N and P omission.

Variations in oil, protein, fatty acids and vitamin E contents of pumpkin seeds under deficit irrigation

In the present study, pumpkin (Cucurbita Pepo L.) was grown under water stress to determine its effects on the chemical composition of the seeds (i.e., oil, protein, fatty acids and vitamin E), in Kayseri, Turkey. Irrigation treatments were designed to supply different portions of depleted moisture within the efficient root zone of the plants (60 cm). The treatments were arranged as supplying 100% (I100), 80% (I80), 60% (I60), 40% (I40), 20% (I20) and 0% (I0) of depleted moisture through a drip irrigation system. The effects of irrigation levels on the oil content of pumpkin seeds were found to be significant (p < 0.01). The oil contents of irrigation treatments varied between 26% (I0, dry) and 64% (I100, full irrigation). However, the effects of deficit irrigation on protein, fatty acids and vitamin E contents were not found to be significant. The vitamin E contents varied from 41.6 – 55.3 mg/100 g; while the protein contents varied from 28.5–37.7%. Six different fatty acids (linolenic, linoleic, oleic, stearic, palmitic and myristic acid) were examined. The average concentration of palmitic, stearic, oleic and linoleic acids ranged from 10.7–12.6%, 6.4–10.4%, 39.6–48.9% and 32.4–35%, respectively. Myristic and linolenic acids were not detected in the pumpkin seeds.