Response of yield and quality of cauliflower varieties (Brassica oleracea var. botrytis) to nitrogen supply

Summary

The fertilizer nitrogen (N) inputs to some vegetables such as cauliflower (Brassica oleracea var. botrytis) can be large. One approach to decreasing the input of N may be to select for cultivars efficient in the use of nitrogen. The objective of this investigation was to identify a cultivar which was nitrogen efficient in terms of producing a high yield under nitrogen (N) limiting conditions. Field trials were conducted in 1993 and 1994 with the cauliflower F₁-hybrids (B..oleracea var. botrytis) `Marine', `Lindurian' and `Linford' at the Ruthe (Germany) and Schermer (the Netherlands) sites. Optimum N supply was 250 kg ha<sup>21</sup> as the sum of the inorganic N content of the soil (N<sub>min</sub>) at planting and fertilizer N. Limiting N supply consisted of N<sub>min</sub> at planting and mineralization of N during cultivation. The N<sub>min</sub> at planting was 116 and 66 kg ha<sup>21</sup> at Ruthe and 84 and 20 kg ha<sup>21</sup> at Schermer in 1993 and 1994, respectively. The yield in terms of total dry-matter and quality (measured as percentage class 1 curds) was highest with `Marine' both at limiting and optimum N supply. Additionally, in quality `Marine' was the least sensitive variety to N shortage. Thus, `Marine' could be regarded as being nitrogen efficient. `Linford' could be considered as nitrogen inefficient in quality, whereas `Lindurian' generally performed inconsistently. The reduction in quality with N shortage was due to an increase in loose curds, indicating that limiting N supply promoted the process of bolting. Quality defect buttoning increased in part with N shortage. `Marine' produced no buttoned curds. Bracting was not affected by N supply and appeared only in Ruthe 1994 with `Lindurian' and `Linford'. It was concluded that the improved efficiency with `Marine' in terms of total dry matter and quality might have been achieved either through a higher N uptake capacity of the root system (uptake efficiency) and/or through a greater utilization of nitrogen by the plant (N utilization efficiency).     

Suspected aspirin resistance in individual healthy adult warmblood horses

The reasons for this prospective experimental study were to determine a dosing scheme with loading and maintenance dose of aspirin inducing inhibition of platelet function measured by whole blood impedance aggregometry. Ten horses received aspirin orally in the morning with one loading dose of 4.7–5 mg/kg and maintenance doses of 1–1.3 mg/kg daily the following 4 days. Aggregometries (COLtest, ASPItest, ADPtest) and serum salicylic acid were measured. ASPItest showed significant difference in inhibition at 24 and 48 hr (p < .05) and 96 hr (p < .01). Significant change for ADPtest and COLtest couldn't be detected. Serum salicylic acid concentrations were significantly (p < .01) increased at 6 and 12 hr. Despite this, three horses failed any inhibitory effect of platelet function, suspecting an aspirin resistance. Regarding the other seven horses platelet aggregation induced by ASPItest was reduced between 37% and 100% from baseline at 6 and 12 hr and between 0 and 98% during the next 4 days. Correlations of serum concentration of salicylic acid and aggregometries couldn't be detected. It can be presumed that equine platelets are less susceptible to aspirin what may compromise eventually the anticoagulatory effects and efficacy in preventing and treating diseases with increased platelet activation as endotoxaemia or laminitis.     

Genotypic variation of potato for phosphorus efficiency and quantification of phosphorus uptake with respect to root characteristics

Potato (Solanum tuberosum L.), an important food crop, generally requires a high amount of phosphate fertilizer for optimum growth and yield. One option to reduce the need of fertilizer is the use of P‐efficient genotypes. Two efficient and two inefficient genotypes were investigated for P‐efficiency mechanisms. The contribution of root traits to P uptake was quantified using a mechanistic simulation model. For all genotypes, high P supply increased the relative growth rate of shoot, shoot P concentration, and P‐uptake rate of roots but decreased root‐to‐shoot ratio, root‐hair length, and P‐utilization efficiency. Genotypes CGN 17903 and CIP 384321.3 were clearly superior to genotypes CGN 22367 and CGN 18233 in terms of shoot–dry matter yield and relative shoot‐growth rate at low P supply, and therefore can be considered as P‐efficient. Phosphorus efficiency of genotype CGN 17903 was related to higher P‐utilization efficiency and that of CIP 384321.3 to both higher P‐uptake efficiency in terms of root‐to‐shoot ratio and intermediate P‐utilization efficiency. Phosphorus‐efficient genotypes exhibited longer root hairs compared to inefficient genotypes at both P levels. However, this did not significantly affect the uptake rate and the extension of the depletion zone around roots. The P inefficiency of CGN 18233 was related to low P‐utilization efficiency and that of CGN 22367 to a combination of low P uptake and intermediate P‐utilization efficiency. Simulation of P uptake revealed that no other P‐mobilization mechanism was involved since predicted uptake approximated observed uptake indicating that the processes involved in P transport and morphological root characterstics affecting P uptake are well described.     

Uncommon disease symptoms caused by Fusarium oxysporum in tulips forced in the glasshouse after pre-cooling at 5°C

Rapidly developing disease symptoms not normally found in tulip bulb cultivation in The Netherlands are described. Mycelium of the fungus is present mainly in the parenchymatic tissues, giving further evidence that the fungus is not a vascular parasite in tulips. There are indications that enzymes or other compounds are involved in the syndrome. Possible factors influencing this uncommon disease development are mentioned.Samenvatting Een snelle ontwikkeling van ziektesymptomen wordt beschreven, die bij de normale teelt van tulpen in Nederland niet bekend is. Mycelium werd hoofdzakelijk aangetroffen in de parenchymatische weefsels, zowel inter- als intracellulair. Dit geeft een verdere steun aan de opvatting dat de schimmel in de tulp geen vaatparasiet is. Er bestaan aanwijzingen, dat enzymen of andere stoffen een rol spelen bij het ontstaan van dit ziektebeeld. Faktoren, die wellicht een rol spelen worden genoemd.     

Phase-matched generation of coherent soft X-rays

Phase-matched harmonic conversion of visible laser light into soft x-rays was demonstrated. The recently developed technique of guided-wave frequency conversion was used to upshift light from 800 nanometers to the range from 17 to 32 nanometers. This process increased the coherent x-ray output by factors of 10(2) to 10(3) compared to the non-phase-matched case. This source uses a small-scale (sub-millijoule) high repetition-rate laser and will enable a wide variety of new experimental investigations in linear and nonlinear x-ray science.     

Origin of mountains on Io by thrust faulting and large-scale mass movements

Voyager stereoimages of Euboea Montes, Io, indicate that this mountain formed when a large crustal block was uplifted 10.5 kilometers and tilted by approximately 6 degrees. Uplift triggered a massive slope failure on the northwest flank, forming one of the largest debris aprons in the solar system. This slope failure probably involved relatively unconsolidated layers totaling approximately 2 kilometers in thickness, overlying a rigid crust (or lithosphere) at least 11 kilometers thick. Mountain formation on Io may involve localized deep-rooted thrust faulting and block rotation, due to compression at depth induced during vertical recycling of Io's crust.