ALBERT

Beschreibung: In agroforestry systems (AFS), trees shade the understory crop to a certain extent. Potato is considered a shade-tolerant crop and was thus tested under the given total solar irradiance and climatic conditions of Southwestern Germany for its potential suitability in an AFS. To gain a better understanding of the effects of shade on growth, yield and quality; a three-year field experiment with different artificial shading levels (12%, 26% and 50%) was established. Significant changes in growth occurred at 50% shading. While plant emergence was not affected by shade, flowering was slightly delayed by about three days. Days until senescence also showed a delay under 50% shade. The number of tubers per plant and tuber mass per plant were reduced by about 53% and 69% under 50% shade. Depending on the year, tuber dry matter yield showed a decrease of 19–44% at 50% shade, while starch content showed no significant differences under shade compared to unshaded treatment. The number of stems per plant, plant height and foliage mass per plant as well as tuber fraction, black spot bruise and macronutrient content were unaffected. Overall, potato seems to tolerate shading and can therefore be integrated in an AFS, and can cope with a reduced total irradiance up to 26%.

Beschreibung: Miscanthus is one of the most promising perennial herbaceous industrial crops worldwide mainly due to its high resource-use efficiency and biomass yield. However, the extent of miscanthus cultivation across Europe is still lagging far behind its real potential. Major limiting factors are high initial costs and low biomass yields in the crop establishment period, especially the first year. This study explores the possibility of establishing miscanthus under maize to generate yields from the first year of cultivation onwards. A field trial with mono-cropped maize and two miscanthus establishment procedures, ‘under maize’ (MUM) and ‘standard’ (REF), was established in southwest Germany in 2016. Annual aboveground biomass was harvested in autumn (2016–2018). In 2016 and 2017, the miscanthus dry matter yield (DMY) was significantly lower in MUM than REF. However, the accumulated DMY of miscanthus and maize was as high in MUM as in maize cultivation alone. In 2018, there was no significant difference between the miscanthus DMY of REF (7.86 ± 0.77 Mg ha−1) and MUM (6.21 ± 0.77 Mg ha−1). The accumulated DMY over the three years was 31.7 Mg ha−1 for MUM, of which 10.1 Mg ha−1 were miscanthus-based, compared to 17.7 Mg ha−1 for REF. These results indicate that miscanthus establishment under maize could compensate for its lack of yield in the first year.

Beschreibung: The tuberous root crop, yacon, is native to the Andean region and contains high amountsof fructooligosaccharides (FOS) with up to 70% of dry matter. Due to FOS, consumption of tubersmay have health-promoting effects. However, regarding the overall cultivation system, norecommendations exist for farmers on nitrogen fertilization and nitrogen (N) uptake of yacon.Therefore, three different N fertilization levels (0, 40, and 80 kg N ha−1) and two genotypes (brownshelled(BG) and red-shelled (RG)) were examined in a two-year field experiment regarding theirtuber yield, sugar composition, and nitrogen uptake. Tuber yields increased with increasingfertilization level and were highest for B80 and R80 (50 and 67 t FM ha−1), while significantdifferences between the genotypes existed. Sugar and the amount of FOS slightly decreased withincreasing N fertilization level, and ranged between 36% and 73% and 30% and 58% of dry matter,respectively. An overall decreasing amount of FOS led to a slight increase in the amount of FOSwith a higher degree of polymerization. Regarding the N-use efficiency of tubers and the total plant,an N fertilization level of 40 kg N ha−1 seems to favor tuber yield.

Beschreibung: Agroforestry, as an improved cropping system, offers some advantages in terms of yield, biodiversity, erosion protection or habitats for beneficial insects. It can fulfill the actual sustainability requirements for bioenergy production like food supply, nature conservation, stop of deforestation. However, competition between intercropped species for water, nutrients and light availability has to be carefully considered. A field trial with shading nets was conducted in Southwest Germany to evaluate the influence of different shading levels (−12, −26, and −50% of full sunlight) on biomass growth, dry matter yield and biogas quality parameters of maize (Zea mays L., cv. ‘Corioli CS’). Shading the plants causes a delayed development, a reduction in height and leaf area index and a slower senescence. Dry matter yields were reduced about 18%, 19%, and 44% compared to 21.05 Mg ha−1 year−1 at full sunlight. Biogas and methane yields were also significantly reduced, the 50% shading treatment showed a reduction of 45% for both parameters. Further, shading led to higher crude protein and crude ash contents. If silage maize is grown under shade, the yields of dry matter, biogas, and methane are nearly halved under 50% shade. Cultivation up to 26% shading could be possible.

Beschreibung: Recent studies have associated the consumption of yacon root as a functional plant food with reduced glycemic index and, due to its considerable phenolic acid levels, a protection of cell membranes against free radical damage. This study examined the effect of four different treatments including: (1) storage duration after harvest (one and three weeks after harvest); (2) pre-treatment before drying (untreated, pre-treatment with diluted lime juice); (3) drying method (freeze drying (FD) and convective hot air drying (CHAD)); and (4) cultivar (white and red), on the quality of yacon (Smallanthus sonchifolius Poepp. and Endl.) chips in terms of their total phenolic content (TPC) and antioxidant activity (AA) (ABTS (2,2′-Azino-Bis (3-Ethylbenzothiazoline-6-Sulfonic Acid) Diammonium Salt) radical scavenging activity, DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity and ferric reducing antioxidant power (FRAP)). Overall, the chips that were produced using pre-treatment with diluted lime juice and FD had the highest amounts of TPC and AA. Regarding the chips produced by means of CHAD, retention of higher TPC and AA was possible with lime-juice pre-treatment and use of higher hot air temperatures. Moreover, chips produced from the white cultivar had higher TPC and AA than chips produced from the red cultivar.

Beschreibung: Yacon (Smallanthus sonchifolius) is a tuberous root crop native to the Andean region. The eatable tubers contain up to 70% fructooligosaccharides (FOS) on a dry matter (DM) basis. These FOS are not digestible by the human intestinal tract and do not cause an increase of blood glucose level. Therefore, the consumption of yacon tubers offers health promoting benefits. With regard to cultivation, little to no information about yield potential and FOS content as well as sugar composition of diverse genotypes is known. However, this information is crucial for the development of new health beneficial food products out of different genotypes of yacon. In the present study nine different genotypes were studied in a field experiment in 2017 and 2018 regarding their tuber yield formation, sugar yield, and sugar composition. The genotypes red-shelled (‘RG’), brown-shelled (‘BG’), and ‘Morado’ reached the highest tuber yields of 46.6, 43.5, and 41.6 t ha−1 FM, respectively. These three genotypes also had the highest sugar yields in the same order (2.2, 2.0, and 1.9 t ha−1). Considering the sugar composition and sugar content, these three genotypes were outstanding, with a sugar content up to 66% of DM (‘RG’, 2018). With regards to the development of possible food products, cv. ‘Peru’ can be considered as favorable for the fresh market due to high amounts of both monosaccharides and FOS. Genotypes ‘BG’, ‘RG’, and ‘Morado’ seem to offer various options for the food processing industry, due to their high amounts of FOS.

Beschreibung: Species-rich hay meadows are usually managed extensively to maintain their biodiversity, with the harvested biomass traditionally being fed to ruminants for milk or meat production. The quality of the biomass is, however, variable, difficult to predict and often does not fulfil today’s requirements. This study established a field trial at two species-rich hay meadows to investigate the combined effect of fertilisation (none, phosphorus and potassium (PK), nitrogen, phosphorus and potassium (NPK)) and date of first cut (at different phenological stages) on biomass quality and quantity. In addition, the most suitable uses of the biomass were explored, including the alternatives biogas and combustion. After four years of the field trial, the stage of maturity at the time of first cut had a greater influence than extensive fertilisation on biomass quality. Dry matter yield (DMY) of the first cut was about 40%–60% of annual DMY (53.99 ± 12.51 dt ha−1 a−1) depending on site, fertilisation and harvest time. Fertilisation had a stronger effect than harvest time on DMY and annual methane yield. In most cases, there was no significant difference in chemical composition between biomass harvested at the end of the grass-flowering stage and at the seed-ripening stage. Thus, a late cut for hay proved to be the most flexible option.

Beschreibung: Climate change will lead to higher frequencies and durations of water limitations during the growing season, which may affect table grape yield. The aim of this experiment was to determine the variability among 3-year old table grape cultivars under the influence of prolonged water deficit during fruit development on gas exchange, growth, and water use efficiency. Six own rooted, potted table grape cultivars (cv. ‘Muscat Bleu’, ‘Fanny’, ‘Nero’, ‘Palatina’, ‘Crimson Seedless’ and ‘Thompson Seedless’) were subjected to three water deficit treatments (Control treatment with daily irrigation to 75% of available water capacity (AWC), moderate (50% AWC), and severe water deficit treatment (25% AWC)) for three consecutive years during vegetative growth/fruit development. Water deficit reduced assimilation, stomatal conductance, and transpiration, and increased water use efficiencies (WUE) with severity of water limitation. While leaf area and number of leaves were not affected by treatments in any of the tested cultivars, the response of specific leaf area to water deficit depended on the cultivar. Plant dry mass decreased with increasing water limitation. Overall, high variability of cultivars to gas exchange and water use efficiencies in response to water limitation was observed. ’Palatina’ was the cultivar having a high productivity (high net assimilation) and low water use (low stomatal conductance) and the cultivar ‘Fanny’ was characterized by the highest amount of total annual dry mass as well as the highest total dry mass production per water supplied during the experiment (WUEDM). Hence, ‘Fanny’ and ‘Palatina’ have shown to be cultivars able to cope with water limiting conditions and should be extensively tested in further studies.

Beschreibung: In soybean production, the shade avoidance response can affect yield negatively in both mono- and inter-cropping systems due to increased heterogeneity of the crop and lodging. This is mainly regulated by photoreceptors responding to the ratio between red and far-red light (R:FR) and photosynthetic photon flux density (PPFD). In this study, three soybean cultivars were grown under different R:FR and PPFD in a light emitting diode (LED) climate chamber to disentangle the effect of each on morphology and dry matter. Results showed that plant organs were influenced differently and indicated an interaction with the increase in assimilates at high PPFD. Internode elongation was mainly influenced by low PPFD with an additive effect from low R:FR, whereas petiole elongation responded strongly under low R:FR. Hence, petiole elongation can be seen as the main response to the threat of shade (high PPFD and low R:FR) and both petiole and internode elongation as a response to true shade (low PPFD and low R:FR). Interactions between cultivar and light treatment were found for internode length and diameter and leaf mass ratio, which may be unique properties for specific cropping systems.