Yield and tuber characteristics of 4x progeny from 2x×2x crosses

Summary Unrelated, unselected 2x haploid-species hybrids that produce 2n eggs, by second division restitution and 2n pollen due to first division restitution were intercrossed to generate 4x progeny. The 19, 4x families were compared with seven cultivars for tuber yield, tuber appearance and tuber set. The mean yield of the 4x families was 30% higher than the mean yield of the cultivars. The best five 4x families outyielded the best five cultivars by 57% and 69% at two locations. Cultivars were superior for tuber appearance and tuber set. The high yields of the 4x families are due to genetic diversity of the 2x parents and their ability to transmit that diversity to the 4x progeny utilizing 2n gametes. The potential of the 2x×2x breeding method is dependent on developing 2x hybrid clones that form 2n eggs and possess desirable tuber types; clones producing 2n pollen and good tuber quality are available.     

Die Problematik düngungsbedingter Höchsterträge aus phytochemischer und ernährungsphysiologischer Sicht

The criteria of yield increases is being subjected to a causal examination. Maximum yields — brought about by large nitrogen supply — are being examined with respect to their influence upon disease potential, increase of quality — and non-parasitic defects as well as upon decrease of useful and increase of undesirable compounds. Observations from the world literature as well as our own experiments with vegetables over many years, particularly with spinach serve as evidence. Stimulation of diseases and pests through overnourishment with nitrogen refer particularly to rust, downy mildew, septoria and botrytis organisms as well as to lice and mites. Amongst non-parasitic diseases one has to list a great number of quality defects, a lessening of resistance against mechanical damage at harvest and during transport, a reduction in quantity of commercial grades, flavour losses and above all a decline of keeping in winter storage. Exessive nitrogen supply also results in a decline in content of valuable constituents and increase in biogenic toxicants as well as in plant components to undesirable levels from a technological and nutritional physiological point of view. Fig. 10 summarises these results. The following valuable constituents are particularly affected: dry matter, total sugar, vitamin C, essential oils and potassium, magnesium and phosphoric acid amongst the minerals. Undesirable increase of enzyme activity as well as that of free amino acid content — coupled with a decrease of biological protein value are additional consequences of excess nitrogen fertilizing. Increases of undesirable compounds refer to crude protein (e.g. brewing barley and sugar beet), nitrate nitrogen (spinach) potentially a health hazard to infants (methaemoglobinemia) in case where toxic nitrite is formed in the spinach from nitrate. The removal of watersoluble nitrate from spinach overnourished with nitrogen by prolonged blanching, suggested in some publications, is to be rejected owing to the then unavoidable in part enhanced losses of water soluble compounds of nutritive value, including vitamins and minerals.     

Isolation and characterization of a Mn(II)-oxidizing Bacillus strain from the demosponge Suberites domuncula

In this study we demonstrate that the demosponge Suberites domuncula harbors a Mn(II)-oxidizing bacterium, a Bacillus strain, termed BAC-SubDo-03. Our studies showed that Mn(II) stimulates bacterial growth and induces sporulation. Moreover, we show that these bacteria immobilize manganese on their cell surface. Comparison of the 16S rDNA sequence allowed the grouping of BAC-SubDo-03 to the Mn-precipitating bacteria. Analysis of the spore cell wall revealed that it contains an Mn(II)-oxidizing enzyme. Co-incubation studies of BAC-SubDo-03 with 100 μM MnCl(2) and >1 μM of CuCl(2) showed an increase in their Mn(II)-oxidizing capacity. In order to prove that a multicopper oxidase-like enzyme(s) (MCO) exists in the cell wall of the S. domuncula-associated BAC-SubDo-03 Bacillus strain, the gene encoding this enzyme was cloned (mnxG-SubDo-03). Sequence alignment of the deduced MCO protein (MnxG-SubDo-03) revealed that the sponge bacterium clusters together with known Mn(II)-oxidizing bacteria. The expression of the mnxG-SubDo-03 gene is under strong control of extracellular Mn(II). Based on these findings, we assume that BAC-SubDo-03 might serve as a Mn reserve in the sponge providing the animal with the capacity to detoxify Mn in the environment. Applying the in vitro primmorph cell culture system we could demonstrate that sponge cells, that were co-incubated with BAC-SubDo-03 in the presence of Mn(II), show an increased proliferation potential.     

Development of locally-adapted faba bean cultivars for organic conditions in Germany through a participatory breeding approach

Organic farming requires cultivars that are specifically adapted to this low input cropping system. Hence, organic farmers and scientists joined in a participatory breeding approach to develop region-specific genotypes of spring faba bean for organic conditions in Germany. A set of 49 genotypes with contrasting degrees of heterozygosity and heterogeneity was used in field trials across five locations in Germany during 3 years 2004, 2005 and 2006. The material involved 18 inbred lines, their 18 polycross progenies, one blend of inbred lines, one blend of polycross progenies, one blend of hybrids and ten checks. Inbred lines are uniform, thus giving the option to be specifically adapted; whereas the polycross progenies and synthetics (Syn-1; predicted from the inbred lines and polycross progenies performance) are partly heterogeneous and heterozygous, thus giving the option to evolve. Agronomic performance was assessed and a “personal appreciation” score of the material was assigned to each genotype by each partner. This personal appreciation was strongly influenced by biotic and abiotic constraints faced by the crop in each location and by the expected grain yield of the genotypes. Uniformity was apparently appreciated by organic farmers. In all locations, the highest yielding inbred line yielded slightly better than the predicted highest yielding synthetic. However, this slight disadvantage of the synthetic is very likely to disappear if the synthetic (Syn-1) is propagated during successive generations.     

Responses of the parthenogenetic isopod, Trichoniscus pusillus (Isopoda: Oniscidea), to changes in food quality

Long-term observations of Trichoniscus pusillus revealed that chemical composition and microbial activity of the leaf litter serving as food influenced the reproductive success of females and the mortality rates of juveniles as well. Of the food sources investigated, only alder litter, exhibiting high microbial activity, allowed the maintenance of a stable population with frequently reproducing females. This study concludes that the food type is a significant factor for population parameters of this parthenogenetic isopod. Our results on T. pusillus, belonging to the taxon Synocheta, are compared with data on terrestrial isopod species of the taxon Crinocheta.