利用根管法对油菜和冬小麦苗期根系形态的研究

快速、准确的根系原位观测方法是根系研究中的重要技术,本研究介绍了一种根管盆栽方法,该方法在透明PVC管内种植作物,通过遮光膜保持管内黑暗环境,以实现在作物生长过程中对其根系生长的原位动态观测,且根系生长环境更接近田间实际情况,并可通过改变根管长度、半径等将其应用于田间深根作物的研究中。利用此方法、结合根系扫描技术分析了油菜和冬小麦从发芽到出苗后16 d时的根系生长情况。结果表明,出苗后7和16 d冬小麦根系和地上部干物重均大于油菜,出苗后16 d冬小麦和油菜根冠比分别为0.513和0.372。大部分根系分布在0~16 cm表层土壤中,出苗后16 d冬小麦和油菜表层土壤中的根长在总根长中的比例分别为62.60%和67.76%,根系总表面积、总体积和一级侧根数均为表层土壤中占比最多,在出苗后7 d,总根长、总表面积、总体积和一级侧根数均为冬小麦显著高于油菜,而在出苗后16 d,两种作物的总根长和总表面积差别不大,说明油菜根系生长呈先缓后快趋势。表层土壤中根系平均直径小于底层土壤,油菜根系平均直径小于冬小麦,油菜和冬小麦的根系直径均大部分在0~0.50 mm之间,随着根系生长,较细的侧根逐渐增多,根系平均直径变小。出苗后16 d内的冬小麦根系伸长速率为1.83 cm/d,大于油菜的1.51 cm/d。因此,冬小麦苗期根系生长快于油菜,油菜根系呈先缓后快的生长特性。本研究介绍的根管法是一种原位研究根系的有效方法。     

Predicting spring barley yield from variety-specific yield potential, disease resistance and straw length, and from environment-specific disease loads and weed pressure

For low-input crop production, well-characterised varieties increase the possibilities of managing diseases and weeds. This analysis aims at developing a framework for analyzing grain yield using external varietal information about disease resistance, weed competitiveness and yield potential and quantifying the impact of susceptibility grouping and straw length scores (as a measure for weed competitiveness) for predicting spring barley grain yield under variable biotic stress levels. The study comprised 52 spring barley varieties and 17 environments, i.e., combinations of location, growing system and year. Individual varieties and their interactions with environments were analysed by factorial regression of grain yield on external variety information combined with observed environmental disease loads and weed pressure. The external information was based on the official Danish VCU testing. The most parsimonious models explained about 50% of the yield variation among varieties including genotype-environment interactions. Disease resistance characteristics of varieties, weighted with disease loads of powdery mildew, leaf rust and net blotch, respectively, had a highly significant influence on grain yield. The extend to which increased susceptibility resulted in increased yield losses in environments with high disease loads of the respective diseases was predicted. The effect of externally determined straw length scores, weighted with weed pressure, was weaker although significant for weeds with creeping growth habit. Higher grain yield was thus predicted for taller plants under weed pressure. The results are discussed in relation to the model framework, impact of the considered traits and use of information from conventional variety testing in organic cropping systems.     

Importance of growth characteristics for yield of barley in different growing systems: will growth characteristics describe yield differently in different growing systems?

The interest in organic grown cereals has increased the need for variety tests under organic growing systems and/or the knowledge on whether growth characteristics describe yield differently under conventional and organic conditions. This paper is a contribution to that question by examining the relationships between some important growth characteristics in barley trials in both systems in Northern Sweden and in Denmark. Mixed model analyses were used for regressions of growth characteristics (or transformations of those) on yield (and log-transformed yield), allowing the slope to depend on the growing system. The analyses showed that diseases seemed to have a less negative effect on yield in the organic growing system than in the conventional growing system if pesticides were not applied. For other characteristics the effect depended on the country. This was the case for grain characteristics where the effect of volume weight in the Swedish trials was much larger in the conventional growing system than in the organic growing system, while a non-significant difference in the opposite direction was found for the trails from Denmark. For the trials from Denmark the effect of grain weight was much larger in the organic growing system than in the conventional growing system, but there was only a small and non-significant difference in the Swedish trials. In both countries there was a significant interaction between the two grain characteristics.     

Performance of spring barley varieties and variety mixtures as affected by manure application and their order in an organic crop rotation

Abstract

In order to obtain a high and stable yield of organic spring barley, production should be optimized according to the specific environment. To test the performance of spring barley varieties under varying cropping conditions, a field experiment was carried out in 2003 and 2004 in a six-field mixed organic crop rotation. We investigated the choice of variety, the order in a rotation, and the application of manure (slurry and farmyard manure; 0 to 120 total-N ha^?1) on grain yields of six selected varieties with different characteristics grown in either pure stands or in two spring barley mixtures, each consisting of three varieties.

Average grain yield of the barley varieties varied between 3.3 t DM ha^?1 and 4.1 t DM ha^?1. Grain yields of the two mixtures were 4.0 and 3.6 t DM ha^?1, respectively. The varieties/mixtures interacted with crop order and year. Foliar diseases were more severe in the barley following grass-clover with large annual differences in the individual diseases. Despite different rooting depths and nutrient uptake patterns, there was no interaction between variety/mixture and the manure input regarding grain yield.

In the 1^st year after grass-clover, one of the two mixtures gave higher grain yield than the average yield of the individual varieties in the mixture. This was not the case in the 4^th year after grass-clover and for the second variety mixture. Thus, although the present results did not indicate that some barley varieties were better adapted to conditions with low manure input than others, variety mixtures that give a robust and stable organic production may potentially be developed.     

Photonic crystal light collectors in fish retina improve vision in turbid water

Despite their diversity, vertebrate retinae are specialized to maximize either photon catch or visual acuity. Here, we describe a functional type that is optimized for neither purpose. In the retina of the elephantnose fish (Gnathonemus petersii), cone photoreceptors are grouped together within reflecting, photonic crystal-lined cups acting as macroreceptors, but rod photoreceptors are positioned behind these reflectors. This unusual arrangement matches rod and cone sensitivity for detecting color-mixed stimuli, whereas the photoreceptor grouping renders the fish insensitive to spatial noise; together, this enables more reliable flight reactions in the fish's dim and turbid habitat as compared with fish lacking this retinal specialization.     

Cytotoxic ellagitannins from Reaumuria vermiculata

Three ellagitannins and one disulfated flavonol were isolated from the aerial parts of Reaumuria vermiculata L. Besides that, 16 known compounds were characterized as well. The structures of all compounds were elucidated on the basis of spectroscopic data including 1D and 2D NMR and ESI HR-FTMS. The in vivo antioxidant activity using the oxygen radical absorbance capacity (ORAC) method, of the extract, its column fractions and two of the isolated ellagitannins was accomplished. In addition, a possible cytotoxicity of the extract and two of the new ellagitannins on HaCaT human keratinocytes and the activity of both compounds against the prostate cancer cell line (PC-3) were also assessed, whereby a potent cytotoxicity with IC(50) less than 1μg/ml was determined for both compounds. Besides, the extract exhibited a potential cytotoxic effect against four different solid tumor cell lines, namely liver (Huh-7), colorectal (HCT-116), breast (MCF-7) and prostate (PC-3). The IC(50)s were found to be substantially low (ranged from 1.3±0.15 to 2.4±0.22μg/ml) with relatively low resistance possibility reaching to 0% in the case of Huh-7 cell.     

Simulation of vegetation cover on sidewalks in Denmark

Data from five 3-year experiments comparing different strategies of non-chemical weed control were analysed in order to set up a model that could be used for simulating further strategies. The treatments included different frequencies and effects of weed control using flaming, steaming and weed brushing. Each plot consisted of about 100 m of sidewalk. The amount of weed on the sidewalks was recorded several times during the 3-year period using a system of cameras mounted on a Terrain Vehicle moving on the sidewalk and post processing using image analyses of extracted images. The percentage of sidewalk covered by weed was estimated on the basis of the image analyses. The model used for describing the weed coverage comprises three components. The first component describes the growth of weeds; the second describes reduction caused by wearing and decay of weeds in the autumn and the third describes the reduction caused by weed control using weed brushing, steaming and flaming. The parameters of the model were estimated from the data for later use for simulating additional strategies.