A comparison of statistical methods for assessing winter wheat grain yield stability

The multitude of existing methods for assessing the phenotypic stability of plants makes breeders be faced with the problem of choosing an appropriate variant. The purpose of this study was to compare different methods of analyzing the genotype x environment interaction and, on their basis, assess the stability of the yield of 7 varieties of winter wheat. The article compares 17 stability statistics by applying them to data obtained from agrotechnical experiments carried in 2009-2011 for evaluating the grain yield of 7 varieties of winter common wheat of Siberian selection (Novosibirskaya 32, Novosibirskaya 40, Novosibirskaya 51, Novosibirskaya 3, Novosibirskaya 2, Obskaya winter, Omskaya 6). Analysis of variance revealed a significant (p < 0.001) genotype x environment interaction in the experiments, which indicates a different reaction of genotypes to changes in environmental conditions. Genotypes were ranked according to the level of stability. Based on the analysis of the rank correlation matrix, the stability statistics were categorized in five groups. Recommendations were made on which group of methods to use depending on the objectives of the study. In the case when the goal of breeding research is the selection of the most biologically stable varieties with the minimum variance across a range of environments, one should use the methods of the static concept. If it is necessary to choose a genotype with a predictable reaction to changes of environmental conditions, corresponding to the calculated level or forecast, the regression approach is the most appropriate. The stability statistics generally identified Novosibirskaya 32 as the most stable variety from a biological point of view. The regression approach showed that Novosibirskaya 3 was the genotype with the smallest deviation from mean yield in all environments, while methods accessing the contribution of each genotype to the genotype x environment interaction defined Novosibirskaya 51 as the most stable variety

Change in the Structure of Asphaltene Macromolecules of the Krapivinskoye Oil Field During Biological Oxidation

С использованием физико-химических методов исследования (элементный анализ, ИК‑спектроскопия, селективная химическая деструкция сульфидных и эфирных связей, хроматомасс-спектрометрия) изучено влияние процессов биодеструкции на состав и структуру асфальтенов легкой нефти Крапивинского месторождения. Приведены результаты сравнительной характеристики исходных асфальтенов и асфальтенов после биодеструкции. Внимание уделено изучению их структурных параметров и состава фрагментов, связанных в молекулах асфальтеновых веществ через эфирные и сульфидные мостики. Показано, что микробное окисление асфальтенов легкой нефти аборигенной почвенной микрофлорой (лабораторный эксперимент) происходит через серию каталитических процессов с образованием промежуточных продуктов превращения – спиртов, альдегидов, кетонов и жирных кислот. Установлено, что «серо- и эфиросвязанные» фрагменты в молекулах асфальтенов биодеградированной нефти различаются от «связанных» соединений в структуре исходных асфальтенов качественным составом насыщенных и ароматических углеводородов и гетероатомных компонентовUsing physico-chemical methods of research (elemental analysis, infrared spectroscopy, selective chemical destruction of sulfide and ester bonds, chromatomass spectrometry) the influence of biodegradation processes on the composition and structure of asphaltenes of light oil at the Krapivinskoye deposit was studied. The results of comparative characteristics of initial asphaltenes and asphaltenes after biodestruction are presented. Attention is paid to studying their structural parameters and composition of fragments bound in asphaltene molecules through ester and sulfide bridges. It has been shown that microbial oxidation of asphaltenes of light oil by aboriginal soil microflora (laboratory experiment) occurs through a series of catalytic processes with formation of intermediate products of transformation – alcohols, aldehydes, ketones and fatty acids. It has been established that “grey and ether-bound” fragments in asphaltene molecules of biodegradable oil differ from “bound” compounds in the structure of the original asphaltenes with the qualitative composition of saturated and aromatic hydrocarbons and heteroatomic component