Inga Smit

Bee pollination improves crop quality, shelf life and commercial value

Pollination improves the yield of most crop species and contributes to one-third of global crop production, but comprehensive benefits including crop quality are still unknown. Hence, pollination is underestimated by international policies, which is particularly alarming in times of agricultural intensification and diminishing pollination services. In this study, exclusion experiments with strawberries showed bee pollination to improve fruit quality, quantity and market value compared with wind and self-pollination. Bee-pollinated fruits were heavier, had less malformations and reached higher commercial grades. They had increased redness and reduced sugar–acid–ratios and were firmer, thus improving the commercially important shelf life. Longer shelf life reduced fruit loss by at least 11%. This is accounting for 0.32 billion US

Nitrogen fertilisation increases biogenic amines and amino acid concentrations in Vitis vinifera var. Riesling musts and wines.

of the 1.44 billion US

Identification of regulated proteins in naked barley grains (Hordeum vulgare nudum) after Fusarium graminearum infection at different grain ripening stages.

provided by bee pollination to the total value of 2.90 billion US

Organically grown tomato (Lycopersicon esculentum Mill.): bioactive compounds in the fruit and infection with Phytophthora infestans.

made with strawberry selling in the European Union 2009. The fruit quality and yield effects are driven by the pollination-mediated production of hormonal growth regulators, which occur in several pollination-dependent crops. Thus, our comprehensive findings should be transferable to a wide range of crops and demonstrate bee pollination to be a hitherto underestimated but vital and economically important determinant of fruit quality.

Differential effects of varied potassium and magnesium nutrition on production and partitioning of photoassimilates in potato plants

BACKGROUND Wines rich in biogenic amines can cause adverse health effects to the consumer. Being nitrogen-containing substances, the amount of amines in wines might be strongly influenced by the rate of nitrogen fertiliser application during grape production. The aim of this work was to evaluate the effect of nitrogen fertilisation in the vineyard on the formation of biogenic amines in musts and wines. RESULTS In a field experiment which compared unfertilised and fertilised (60 and 150 kg N ha(-1)) vines over two separate years, the total amine concentrations in must and wine increased. The latter was due to an increase of individual amines such as ethylamine, histamine, isopentylamine, phenylethylamine and spermidine in the musts and wines with the nitrogen application. Furthermore, the fermentation process increased the concentration of histamine and ethylamine in most of the treatments, while spermidine, spermine and isopentylamine concentrations generally decreased. Throughout both vintages, the concentrations of tyramine and histamine of the investigated musts and wines never reached detrimental levels to the health of non-allergenic people. CONCLUSIONS Nitrogen fertilisation has a significant effect on amines formation in musts and wines. Furthermore, during fermentation, ethylamine and histamine increased while other amines were presumably serving as N sources during fermentation.

Environmental Growing Conditions in Five Production Systems Induce Stress Response and Affect Chemical Composition of Cocoa (Theobroma cacao L.) Beans

UNLABELLED We analyzed the effect of Fusarium graminearum infection on field-grown naked barley (Hordeum vulgare nudum). The ears were inoculated with F. graminearum spores during anthesis. In the course of ripening, grains in five phenological growth stages of naked barley from milk ripe to plant death were sampled. The albumin and globulin proteins of inoculated grains and untreated (control) grains were separated by two-dimensional gel electrophoresis. Forty-five spots composing of proteins that were changed in abundance due to F. graminearum infection were subsequently identified by mass spectrometry. Various proteins showing altered expression pattern after Fusarium infection were linked to stress response such as plant signal transduction pathways, fungal defense and oxidative burst. More proteins changed during early grain ripening stages than during later ripening stages. Protease inhibitors occurred at increased abundancy during milk ripe stage. A thaumatin-like protein accumulated at plant death stage. Proteins linked to nitrogen metabolism and protein biosynthesis were mainly reduced, whereas those linked to carbon metabolism were predominantly increased in infected grains. BIOLOGICAL SIGNIFICANCE Fusarium graminearum infection can lead to significant contamination of grains with mycotoxins. With this 2D-based proteomics study we give an insight into plant–pathogen interactions between the non-model plant naked barley and the fungus F. graminearum during five stages of grain development. Over the multiple developmental stages we observed specific patterns of changes induced by the fungus: the primary plant metabolism and inhibition of fungal protease were predominantly affected during early grain development stages. During the entire grain development we found an induced accumulation of thaumatin-like proteins due to the fungal infection indicating their fundamental role for naked barley defense.

The significance of organic‐anion exudation for the aluminum resistance of primary triticale derived from wheat and rye parents differing in aluminum resistance

BACKGROUND Tomato fruits are characterized by a good nutritional profile, including different bioactive compounds such as carotenoids, phenolic compounds and ascorbic acid. The objective of this study was to analyze the content of bioactive compounds in the fruit and the infection by Phytophthora infestans of 28 tomato genotypes from organic outdoor production. The relationship between bioactive compounds in the fruit and infection with P. infestans was estimated. Field experiments were carried out in 2004 and 2005 at two locations in central Germany. RESULTS Significant variation among genotypes, locations and years was observed for the content of lycopene, ascorbic acid, total phenolic compounds, antioxidant capacity and the infection level of P. infestans. Antioxidant capacity seemed to be influenced mainly by the phenolics and was highest in small fruits, which were less infected with P. infestans. CONCLUSION The large genetic variation among tomato genotypes for the content of bioactive compounds in their fruit allows for selection gains. None of the investigated bioactive compounds can be recommended for the indirect selection for increased field resistance against P. infestans.

Insect pollination as a key factor for strawberry physiology and marketable fruit quality

Potassium (K) and magnesium (Mg) are essential macronutrients for plants; they play crucial roles for photoassimilate production and transport. The knowledge on both individual and interactive effects of K and Mg nutrition in potato (Solanum tuberosum L.) is limited. We aimed to determine whether K or Mg deficiencies impair photoassimilate production and transport, and consequently the development of tubers which are strong sink organs for photoassimilates. Potato plants were grown in pots using sand culture under various K and Mg supplies. Biomass production, CO2 net assimilation, leaf sugar concentrations and transcript levels of H+ /sucrose symporters in leaves were measured. Both K and Mg deficiencies reduced CO2 net assimilation and biomass production, with stronger reductions during K deficiency. Sugars accumulated in K- and, more importantly, in Mg-deficient leaves. Low K or Mg supplies resulted in increased transcript levels of H+ /sucrose symporters, but the increase was less pronounced during Mg deficiency. The lower increase of transcript levels of H+ /sucrose symporters under Mg deficiency was probably caused by an impaired sucrose transport already at an earlier step, namely the efflux of sucrose from mesophyll cells into the apoplast. Thus, we assume that K and Mg deficiencies caused sugar accumulation in separated cell compartments of source leaves leading to a different impact on the gene expression of sucrose transport systems. Tuber sugar and starch concentrations, however, remained unaffected under the various treatments. Nevertheless, the total amount of tuber sugar and starch per plant decreased significantly during K and Mg deficiencies. This article is protected by copyright. All rights reserved.

Einfluss von Kalium und Magnesium auf Prozesse der Qualitätsbildung in der Kartoffel

Cocoa beans are produced all across the humid tropics under different environmental conditions provided by the region but also by the season and the type of production system. Agroforestry systems compared to monocultures buffer climate extremes and therefore provide a less stressful environment for the understory cocoa, especially under seasonally varying conditions. We measured the element concentration as well as abiotic stress indicators (polyamines and total phenolic content) in beans derived from five different production systems comparing monocultures and agroforestry systems and from two harvesting seasons. Concentrations of N, Mg, S, Fe, Mn, Na, and Zn were higher in beans produced in agroforestry systems with high stem density and leaf area index. In the dry season, the N, Fe, and Cu concentration of the beans increased. The total phenolic content increased with proceeding of the dry season while other abiotic stress indicators like spermine decreased, implying an effect of the water availability on the chemical composition of the beans. Agroforestry systems did not buffer the variability of stress indicators over the seasons compared to monocultures. The effect of environmental growing conditions on bean chemical composition was not strong but can contribute to variations in cocoa bean quality.