Einfluss Weicher Röntgenstrahlen und Mechanischer Effekte auf das Keimen von Kartoffeln

Zusammenfassung Um eine schonende Keimhemmung bei Kartoffeln der SorteBona zu erzielen, wurden Versuche mit sehr weichen R?ntgenstrahlen von 12 keV Energie durchgeführt. Sogar mit einer Bestrahlungsdosis von 10.000 bis 15.000 r wird — bei der hier angewandten weichen R?ntgenstrahlung — eine über 22 Wochen andauernde Keimhemmung erreicht ohne Verschlechterung des ?usseren Ansehens und Geschmacks. Der Schwund der Knollen wurde einzeln bis 5.000 r gemessen und mit anwachsender Dosis bis zu 15.000 r eine starke Verminderung des Schwundes erzielt. Au?erdem wurde nachgewiesen, da? durch langstündiges, vorsichtiges Rollen in der beschriebenen Versuchsanordung ebenfalls eine Keimhemmung zu erreichen ist. Es wird versucht, diese Erscheinung biologisch und rechnerisch zu deuten. Aus praktischen Gründen w?re es wünschenswert, den neuen, erw?hnten Effekt weiter zu untersuchen.

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Summary In order to bring about sparing sprout inhibition of theBona variety of potatoes experiments were undertaken with very weak X-rays of an energy of 12 keV. A radiation dose of only 10.000 to 15.000 r (with the weak X-radiation employed in this instance) was sufficient to inhibit sprouting for over 22 weeks without adversely affecting the appearance and flavour. The tuber shrinkage was individually measured up to 5.000 r and a marked reduction of shrinkage obtained with an increasing dose up to 15.000 r. It was also shown that sprouting may be inhibited by protracted, careful rolling in the described order of experiments. An attempt is made to explain this phenomenon biologically and analytically. From practical considerations it would be desirable to make a further study of the novel effect referred to.

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Résumé Pour réaliser de fa?on délicate une inhibition de la germination des pommes de terre de la variétéBona, nous avons effectué des essais de traitement par les rayons X très mous d'une énergie de 12 keV. Même l'irradition à une dose de 10.000 à 15.000 r sufit déjà — dans le cas des rayons très mous utilisés dans ces essais — pour inhiber la germination pendant 22 semaines au moins sans nuire à l'aspect ni au go?t des tubercules. La perte de poids des tubercules fut mesurée isolément jusqu'à 5000 r. Les doses croissantes jusqu'à 15.000 r réduisaient fortement la perte de poids. Il a également été constaté que dans les conditions de l'essai, un roulement très lent et doux des tubercules permet aussi de retarder la germination. Nous avons tenté d'expliquer ce phénomène au point de vue biologique et statistique. Pour des raisons pratiques, il serait désirable que l'étude de cet effet nouvellement observé soit approfondie.

     

The distribution and chemical coding of neurons in the celiac-superior mesenteric ganglion complex supplying the normal and inflamed ileum in the pig

The present study investigated the chemical coding of neurons in the celiac-superior mesenteric ganglion complex supplying the normal (n=4) and inflamed (n=4) ileum (chemically-induced inflammation) in juvenile pigs using retrograde tracing combined with immunohistochemistry. Ileum-projecting neurons (IPN) were predominantly distributed in the left and right superior mesenteric pools of the ganglion. The majority of them were adrenergic (tyrosine hydroxylase-positive) and also contained neuropeptide Y, somatostatin or galanin. No clear-cut differences in the distribution and chemical coding of IPN were found between normal and inflamed pigs. However, in the inflamed group, the density of peptidergic, IPN-associated nerve fibres was higher than that found in the control group.     

Effects of lauryl sulphate on egg‐shell quality in laying hens

1. The effect of feeding the detergent, sodium lauryl sulphate at concentrations up to 10 g/kg diet on egg‐shell quality was examined in laying hens at 24, 36 and 48 weeks of age.

2. Lauryl sulphate at 2.5 g/kg or more in the diet significantly increased shell breaking strength, shell thickness and shell weight at 24 and 36 weeks. In 48‐week‐old hens only shell breaking strength was increased significantly. Egg production and egg weight were not affected significantly by lauryl sulphate.

3. Lauryl sulphate might increase these measures of quality by increasing shell deposition and/or shell elasticity.     

Carbon kinetics of milk formation in Holstein cows in late lactation

Carbon transfer to milk in Holstein cows in late lactation was measured by introducing changes in the natural stable carbon isotope composition of the feed. Six Holstein cows in mid-lactation were placed on a diet naturally low in 13C (-25.0% vs Pee Dee belemnite [PDB] an international carbon isotope standard), based on alfalfa-barley, and six others were placed on a diet naturally enriched in 13C (-11.5% vs PDB), based on corn. After a 7-wk equilibration period on these diets, three cows were switched from alfalfa-barley to corn, and three were switched from corn to alfalfa-barley. The three other cows in each group served as controls. 13C/12C ratios were measured in daily morning milk samples during the week before and for 6 wk after the changes in diet. After the diets had been switched, milk isotope ratios rapidly approached the isotopic composition of the new diet, indicating rapid transfer of dietary carbon into milk. The data were consistent with a model whereby milk was synthesized from a single precursor pool that responded rapidly to dietary perturbation. The milk precursor pool had a half-life of approximately .9 d and had a mass of approximately 7 kg of carbon, which was renewed daily by the entry of 5 kg of digestible dietary carbon.     

Fertility of Holstein cows and heifers submitted to timed artificial insemination and receiving one or two doses (12 h apart) of semen

The objective of this retrospective study was to assess the effect of receiving a single (n = 50,285) or double (n = 4392) artificial insemination (AI), 12 h apart, within a timed artificial insemination protocol on pregnancy per AI (P/AI) in nulliparous heifers (inseminated with either sex-sorted or conventional semen) and pluriparous Holstein cows in a commercial dairy herd. Also, this study aimed to investigate the relationship between temperature-humidity index (THI) and time of the first AI and fertility. Fertility of cows receiving two AI with normothermia (THI <68) was higher (p < .05) than cows receiving a single AI (42.9% vs. 36.4%). P/AI of cows receiving two AI with severe heat stress (THI >85) was higher (p < .05) than cows receiving a single AI (21.0% vs. 12.6%). Regardless of heat stress conditions, applying the first AI in the morning increased (p < .05) P/AI in cows with double AI than in cows whose first AI occurred in the afternoon (38.4 vs. 33.3%). With moderate heat stress, and sexed-sorted semen, P/AI to timed AI was higher (65.0 vs. 51.9%; p < .05) in heifers receiving double AI than those serviced once. It was concluded that double AI, 12 h apart, enhanced fertility at timed AI than herd mates with a single AI, particularly with heat stress at breeding.     

Effect of carazolol on the oestrous behaviour and concentrations of luteinising hormone and steroids in lactating cows during the periovulatory period

Twelve multiparous, cycling, lactating Holstein-Friesian cows were synchronised with prostaglandin F(2alpha) and treated with either 2.5 mg carazolol or saline. There were no differences between the peripheral blood concentrations of oestradiol or progesterone, but in the cows treated with carazolol the periovulatory surge of luteinising hormone was delayed, and oestrous behaviour was expressed later than in the control cows.     

Spatial and temporal analysis of coffee wilt disease caused by Fusarium xylarioides in Coffea canephora

Coffee wilt disease (CWD) caused by Fusarium xylarioides, considered to be a soil-inhabiting fungus, is endemic in several African countries, affecting commercially important coffee species and causing serious economic losses. Coffee wilt disease development in naturally infected Coffea canephora fields at the Coffee Research Institute in Uganda was assessed from April 2001 to March 2006 to generate information about temporal and spatial spread of the disease. Maps of diseased trees were also generated from the data. Semi-variance analysis was performed on the data to show the spatio-temporal structure of disease. Host influence on the spatio-temporal structure was deduced from the distribution pattern of diseased and healthy trees and analysis of variance. Results show that the temporal disease epidemic progress was slow. The disease was found to spread from initial infections to healthy neighbouring trees, resulting in an aggregated pattern. An infected tree could infect up to three healthy trees away, in any direction. Disease foci formed and expanded with time, coalescing but punctuated in spots planted with resistant hosts. There were varying levels of susceptibility among host genotypes, affecting the rates and levels of epidemic development. The implications of the findings to the control of CWD are discussed.