Diallel analysis of grain quality traits in inbred winter rye lines

The results of a diallel analysis of five inbred winter rye lines for grain quality traits (grain test weight, falling number, protein content, water extract viscosity, hearth bread form ratio, and pan loaf volume) are given. For all traits except bread volume, F₁ hybrids displayed hypothetical heterosis. A substantial contribution to genotypic variance was made both by general (GCA) and specific (SCA) combining ability; however, the proportion of dominance effects was 1.7–3.5 times higher than direct additive effects. The high potential of the grain test weight, falling number, water extract viscosity, hearth bread form ratio, and loaf volume traits determined the effects of dominant genes, and the protein content, the effects of recessive genes. Lines with high GCA estimates for individual traits (H-649, H-451, H-842, and H-1078) were identified. The importance of breeding inbred lines for combinability of high falling number and higher water extract viscosity traits is shown. The possibility of predicting the combining ability on the basis of the value of quality traits in inbred lines per se is concluded.     

Organic matter mineralization in different soil aggregate fractions

The mineralization rate of the organic matter (OM) in the aggregate fractions of a gray forest soil separated by repeated sieving through sieves with different mesh sizes was assessed. The samples of the soil aggregate fractions were incubated for 141 days under constant temperature and moisture, and the C-CO₂ emission rate was measured. The mineralizable OM pool in the aggregates of <0.25, 1–0.25, and 3–1 mm in size from the soil under a forest contained easily (C₁, k ₁ > 0.1 days⁻¹), moderately (C₂, k ₂ > 0.01 days⁻¹), and difficultly (C₃, k ₃ > 0.001 days⁻¹) mineralized compounds; the C₁ and C₂ components were present in the coarser aggregates. In the arable soil, the C₁, C₂, and C₃ OM components were separated in the aggregates of <0.25 and 1–0.25 mm; the C₁ and C₃ were separated in the aggregates of 3–1 and 5–3 mm; and the C₁ and C₂ were separated in the coarsest (10–5 mm) aggregates. The highest content of potentially mineralized OM (C₀) occurred in the aggregates of 1–0.25 and 3–1 mm, but the size of the mineralizable OM pool was more dependent on the portion of the aggregate fraction in the soil than on the absolute C₀ content in the fraction. It was shown that the decrease in the share of coarse structural aggregates is accompanied by a depletion of potentially mineralized OM in the arable soil, and the formation of coarse aggregates is an important condition of the soil carbon sequestration.     

Influence of moisture on the stability of soil organic matter and plant residues

The effect of three levels of soil moistening on the organic matter mineralization was assessed for three arable soils and wheat straw in the course of a 150-day-long incubation experiment. It was found that the intensity of the organic matter mineralization increased in parallel to soil moistening in the podzolized chernozem and dark-chestnut soil and remained stable in the gray forest soil, which was explained by the low content of easily mineralizable fractions of active organic matter in the latter soil. The mineralization of wheat straw depended on the soil moistening rather than on soil properties.     

Blending Value of Winter Rye with Various Viscosity of an Aqueous Extract of Grain Meal

The wide use of rye flour in the form of rye-wheaten and wheaten-rye mixes has caused the problem of the blending value of cultivated varieties, which is as important for rye as for wheat. The purpose of the research was to comparatively study the blending value of winter rye samples with various viscosity of aqueous extract of grain meal. Six rye samples with low viscosity (2.1–7.3 cP) as recipients and three samples with high viscosity (10.0–15.0 cP) were used as donors. Recipient and donor grains were mixed in the ratio 4: 1, 3: 2, 2: 3, and 1: 4. The following traits were studied: viscosity of aqueous extract (VAE), height of amylogram, falling number, shape stability of a toppling bread (H/D ratio), and volume of pan bread. Blending value of components was estimated based on improvement effect (E). It was shown that viscosity and other quality traits correlatively associated with it were subjected to the mixing rule: their expression naturally increased with increased proportion of the highly viscous donor in the mixture. The exception was the volume of pan bread, the expression of which decreased in this case. During mixing, the actual values of the traits in the mixtures almost completely coincided with the calculated values. Significant deviations from the weighted average values were revealed only for amylogram height and the volume of the pan bread, indicating possible interaction effects of the mixed components. A negative correlation was found between the viscosity level of the recipient and the effect of its improvement (r =–0.93). The most valuable improver in mixtures with low viscous rye was the Moc-12-BB donor, characterized by high expression of the VAE (15.0 cP). It was concluded that such rye could be classified as strong since a lower amount of this rye should be added to the mixture for improvement of the weak (low-viscosity) rye. The addition of highly viscous rye to low viscous rye in an amount of 20–40% was the most preferable.     

Plant Residues Decomposition and Formation of Active Organic Matter in the Soil of the Incubation Experiments

Eurasian Soil Science - The decomposition and mineralization of various plant residues (oak and aspen leaves, pine needles, small branches and thin roots of trees, aboveground biomass and roots of...     

Dynamics of technological and baking qualities of winter rye grain depending on flour yield and water extract viscosity

Dynamics of technological and baking qualities of winter rye grain were studied depending on flour yield and water extract viscosity (WEV). Initial material consisted in six populations of winter rye obtained after ten cycles of divergent selection for WEV, which was carried out on the basis of cultivars Al’fa and Moskovskaya 12. For each cultivar, three populations contrastingly differing for WEV were identified: low viscosity ones (LV) obtained in minus selection, mean viscosity ones (MV) obtained on the basis of the original populations without selection, and high viscosity (HV) ones obtained in plus selection. For each population, three grades of flour were obtained: wholemeal flour (100% yield), medium flour (87% yield), and pure flour (63% yield). Comparative testing was carried out in 2015 and 2016: in a field experiment on 8-m2 plots in three repetitions. The following traits were studied: weight of 1000 grains, nature of grain, glassiness, protein and starch contents, flour whiteness, falling number, amylogram height, starch gelatinization temperature, H/D ratio, bread volume, and crumb porosity. A prominent feature of LV-populations is the trend towards small grains, low grain nature, and lowered starch contents. For most traits, HV-populations were at the level of MV-populations. It was concluded that, during production of pure rye flour, almost all pentosans together with bran are removed from external layers of caryopsis. As a result, the share of pentosans within endosperm essentially increases. These pentosans belong to the water-soluble fraction, which is proven to be true by a sharp increase in WEV in pure rye flour in comparison with wholemeal flour. An increase in WEV in the grades of thin grinding flour occurs due to water-soluble pentosans, which are contained in bran, in deep layers of endosperm. As compared to rough grinding flour (wholemeal flour), thin grinding flour (pure flour) differed by higher whiteness (by 46.6 units), better amylogram (by 46 a. units), higher H/D ratio (by 0.04), volumetric yield (by 38 cm3), and porosity of crumb of a square loaf (by 9.9%). WEV also had significant influence, which, at high expression, positively affected flour whiteness, falling number, amylogram height, starch gelatinization temperature, and shape stability of toppling bread.     

Determinants of trophic modes of the nematophagous fungus Arthrobotrys oligospora interacting with bacterivorous nematode Caenorhabditis elegans

The determinants of saprotrophic or predatory modes of the nematophagous fungus Arthrobotrys oligospora were investigated in soil microcosms and on solid nutrient media. A sterilized soil amended with 1% w/w alfalfa meal (C:N=32) and inoculated with conidia of A. oligospora, showed lower mycelium biomass and higher specific rate of conidia production in the presence of the bacterivorous nematode Caenorhabditis elegans than in its absence. As few as 10 nematodes g⁻¹ soil were sufficient to enhance spore formation by the vegetative mycelium. Given that the fungus was not limited by available carbon and nitrogen, this indicates that nematodes provide essential growth factors regulating the development of A. oligospora. Carbon mineralisation by A. oligospora, measured as the rate of CO₂ production, was found to be 25–35% lower in the presence of 20–60 C. elegans g⁻¹ soil compared to soil without nematodes. This showed that A. oligospora had lower saprotrophic activity in the predaceous phase. Trap formation and nematophagous activity of A. oligospora were observed only where conidia were inoculated on nutrient poor medium (water agar), on low-nitrogen medium (Yeast Carbon Base agar) or on medium containing no amino-acids or vitamins (Czapek-Dox agar). A. oligospora did not form trapping structures when grown on nutrient-rich media containing three amino-acids (l-histidine monohydrocloride, dl-methionine and dl-tryptophan) and vitamins (biotin, calcium pantothenate, folic acid, inositol, niacin, p-aminobenzoic acid, pyridoxine hydrochloride, riboflavine, thiamine hydrochloride). It is concluded that predaceous behaviour of A. oligospora can be regulated either by nitrogen sources or by physiologically active compounds (amino-acids or vitamins) present in nematodes.     

Biokinetic indication of the mineralizable pool of soil organic matter

In three laboratory experiments with gray forest soils, the rates of mineralization of the bacterial mass, green oat mass, and cellulose applied in increasing doses were determined based on the measurement of the C-CO₂ emission. The substances applied were used as biological indicators of the mineralizable organic matter pool in the gray forest soils.     

Abundance, diversity, viability, and factorial ecology of fungi in peatbogs

This review presents an analysis of the results of mycological investigations of peat obtained by the authors and other Russian and foreign scientists. High-moor peat, unlike low-moor peat, is shown to contain great reserves of fungal biomass mainly represented by mycelium. The viability of the mycelium and spores is high in the upper peat horizons and does not exceed 50% in the lower ones. In high-moor peat, fungi that are capable of destroying the complex structural polymers composing up to 50% of the peat rarely occur. The analysis of the factors limiting the activity of fungi in the high-moor peatbogs showed that, in the upper layers, the main factor was the strength of the sphagnum cellular walls. In the lower layers, the significant oxygen deficit and the accumulation of sphagnans, sphagnols, phenol-containing compounds, and antioxidants that block the activity of hydrolytic and oxidizing enzymes are of great importance.     

Change in activity and electrophoretic spectra of certain enzymes in cultivated and wild soybean plant leaves

The activity of catalase and esterase complex in soybean leaves increased in the pod formation stage and that of peroxidase in the seed maturation stage. The maximum value of specific catalase and peroxidase activity was noted in wild soybean leaves. Heterogeneity of catalase and esterases decreased and that of peroxidase increased during leaf ontogeny.