Silicon fractions in Histosols and Gleysols of a temperate grassland site

The importance of silicon (Si) in nutrition is currently being recognized by its beneficial effects on many crops. Therefore, it is important to determine the soil Si status and to examine different extractants for testing plant‐available Si. Little information is available about the Si status of Histosols and C_org‐rich Gleysols in temperate climate. This study was undertaken (1) to characterize different Si pools in C_org‐rich groundwater soils of an experimental site and (2) to study the influences of small‐scale variability on element distribution. At the experimental site, the thickness of the C_org‐rich layer ranges between 4 and 5 dm overlying fine‐sandy fluvial sediments. Four extractants were evaluated: 0.01 M CaCl₂, 0.5 M acetic acid, 0.1 M sodium pyrophosphate, and 0.1 M Tiron (C₆H₄Na₂O₈S₂ · H₂O). Further, total element content was determined following HNO₃/HF digestion. Calcium chloride–soluble Si shows no significant relations to other parameters analyzed. On the basis of published data, the soils investigated could be classified as Si‐deficient. The Si fraction extracted with acetic acid displays relations to C_org content of the soil and a weak correlation to CaCl₂‐soluble Si, indicating that both solutions extract overlapping but not the same fractions. Sodium pyrophosphate extracts mainly organo‐mineral Fe and Al complexes in the soils studied, which is reflected in a highly positive correlation to C_org. Pyrophosphate‐soluble Si showed a negative relationship to C_org, which means a closer relation of this Si fraction to mineral matter than to C_org. The Tiron solution extracted most Si of all extractants, but this amounts only 1% of the total Si content. Taking into account the element‐specific relationship between pyrophosphate and Tiron‐extractable Fe, Al, and Si, it can be concluded that Tiron dissolves mainly the opaline silica present in Histosols and C_org‐rich Gleysols. The distribution of C_org and ash content shows clear spatial trend at the experimental site, which is correlated to pyrophosphate‐extractable as well as total Si. This small‐scale variability of soil parameters itself is related to a distinct microrelief.     

Phytochemical and dietary fiber components in barley varieties in the HEALTHGRAIN Diversity Screen

Ten different barley varieties grown in one location were studied for their content of tocols, folate, plant sterols, alkylresorcinols, and phenolic acids, as well as dietary fiber components (arabinoxylan and beta-glucan). The samples included hulled and hull-less barley types and types with normal, high-amylose, and waxy starch. The aim was to study the composition of raw materials, and therefore the hulls were not removed from the hulled barleys. A large variation was observed in the contents of all phytochemicals and dietary fibers. Two varieties from the INRA Clermont Ferrand barley program in France (CFL93-149 and CFL98-398) had high content of tocopherols and alkylresorcinols, whereas the variety Dicktoo was highest in dietary fiber content and phenolics. Positive correlations were found between 1000 kernel weight, alkylresorcinols, and tocols, as well as between dietary fiber content and phenolic compounds. The results demonstrate that the levels of phytochemicals in barley can likely be affected by breeding and that the contents of single phytochemicals may easily be adjusted by a right selection of a genotype.     

Advocating a need for suitable breeding approaches to boost integrated pest management: a European perspective

Currently, European farmers do not have access to sufficient numbers and diversity of crop species/varieties. This prevents them from designing cropping systems more resilient to abiotic and biotic stresses. Crop diversification is a key lever to reduce pest (pathogens, animal pests and weeds) pressures at all spatial levels from fields to landscapes. In this context, plant breeding should consist of: (1) increased efforts in the development of new or minor crop varieties to foster diversity in cropping systems, and (2) focus on more resilient varieties showing local adaptation. This new breeding paradigm, called here ‘breeding for integrated pest management (IPM)’, may boost IPM through the development of cultivars with tolerance or resistance to key pests, with the goal of reducing reliance on conventional pesticides. At the same time, this paradigm has legal and practical implications for future breeding programs, including those targeting sustainable agricultural systems. By putting these issues into the context, this article presents the key outcomes of a questionnaire survey and experts' views expressed during an EU workshop entitled ‘Breeding for IPM in sustainable agricultural systems’. © 2017 Society of Chemical Industry