ALBERT

Notes: Eleven corn (Zea mays L.) hybrids were evaluated in terms of their growth response to treatment with a high rate (6.7 kg ha−1) of the thiocarbamate herbicide, EPTC, and the chloroacetanilide herbicide, metolachlor. Most of the tested hybrids were more susceptible to treatment with metolachlor than EPTC. It was apparent that the degree of tolerance observed for one of these herbicides was not necessarily matched by a similar degree of tolerance to the other. No correlation between glutathione content and herbicide tolerance was observed for the 11 hybrids tested. A relationship between glutathione S–transferase (GST) activity and metolachlor tolerance was suggested by this study. In general, higher GST activities were characteristic of the more tolerant hybrids. The monooxygenase inhibitor, piperonyl butoxide (PBO), in combination with EPTC resulted in a synergistic effect on eight of the eleven tested hybrids. PBO acted synergistically in combination with metolachlor on only two hybrids and to a lesser extent than with EPTC. Soil treatment with the oxygen evolving compound, calcium peroxide, appeared to have an antagonistic effect on the growth response of ‘Northrup–King 9283’ corn treated with EPTC. In contrast the same treatment had a synergistic effect on the growth response of this hybrid to metolachlor. Both the synergism of EPTC by PBO and the antagonism by calcium peroxide are believed to be due to the importance of monooxygenase activity in the metabolism of EPTC. Tolerance to EPTC is consequently more likely to be influenced by oxidative reactions than is tolerance to metolachlor. Réponses comparées d'hybrides sélectionnés de mai's (Zea mays) a l'EPTC et au métolachlorOnze hybrides de mai's (Zea mays) ont étéétudiés en regard de leur croissance suite à un traitement à une dose é1evée (6.7 kg ha−1) de 1'herbicide thiocarbamate, EPTC et de 1'herbicide chloroacétanilide, métolachlor. La plupart des hybrides testés étaient plus sensibles au métolachlor qu' à l'EPTC. II est apparu que le degré de tolérance observé pour 1'un de ces herbicides n'était pas nécessairement accompagné par un degré similaire de tolérance pour 1'autre. Aucune corrélation entre la teneur en glutathion et la tolérance herbicide n'a été observée pour les 11 hybrides testés. Une relation entre 1'activité de la glutathion S–trans–férase (GST) et la tolérance au métolachlor a été suggérée par cette étude. En général les activités GST plus élevées étaient caractéristiques des hybrides les plus tolérants. L'inhibiteur monooxygénase, le pipéronyl butoxide (BPO) en mélange avec l'EPTC a abouti a un effet synergique sur 8 des 11 hybrides testés. PBO a agis en synergic en mélange avec le métolachlor chez seulement 2 hybrides et à une échelle moindre qu'avec 1'EPTC. Un traitement du sol avec un composé oxygéné, du calcium peroxyde, est apparu avoir un effet antagoniste sur la croisance du mai's ‘Northrup–King 9283’ traitéà l'EPTC.Au contraire, le même traitement a eu un effet de synergie sur la croissance de cet hybride traité au métolachlor. Tant la synergie entre l'EPTC et le PBO, que l'antagonisme avec le calcium peroxidé semblent être liés à l'importance de l'activité monoxygenase dans le métabolisme de l'EPTC. La tolérance à l'EPTC est en conséquence plus étroitement influencée par les réactions oxydantes que la tolérance au métolachlor. Reaktion ausgewählter Mais-Hybriden (Zea mays L.) auf EPTC und MetolachlorDas Wachstum von 11 Mais-Hybriden (Zea mays L.) nach Behandlung mit einem hohen Aufwand (6,7 kg ha−1) des Thiocarbamats EPTC und des Chloracetanilids Métolachlor. Es war deutlich, daß der Grad der Toleranz gegenüber einem dieser Herbizide nicht notwendigerweise dem bei dem anderen entsprach. Bei allen 11 Hybriden konnte keine Korrelation zwischen dem Glutathion-Gehalt und der Herbizidtoleranz gefunden werden. Auf Grund dieser Untersuchung wird eine Beziehung zwischen der Aktivität der Glutathion-S-Transferase (GST) und der Metolachlor-Toleranz angenommen, denn tolerantere Hybriden hatten im allgemeinen eine höhere GST-Aktivität. Der Monooxygenase-Hemmer Piperonylbutoxid (PBO) hatte zusammen mit EPTC eine synergistische Wirkung auf 8 der 11 Hybriden. Mit Metolachlor wirkte PBO synergistisch nur bei 2 Sorten und in geringerem Maße als mit EPTC. Eine Bodenbearbeitung mit dem sauerstoffabgebenden Calciumperoxid hatte offensichtlich eine antagonistische Wirkung auf das Wachstum von ‘Northrup-King 9283’ bei Behandlung mit EPTC. Im Gegensatz dazu wirkte dieselbe Behandlung dieser Hybride mit Metolachlor synergistisch. Es wird angenommen, daß sowohl der Synergismus von EPTC mit PBO als auch der Antagonismus mit Calciumperoxid für die Bedeutung der Monooxygenase-Aktivität für den Metabolismus von EPTC sprechen. Die Toleranz gegenüber EPTC ist deshalb wahrscheinlich mehr durch oxydative Reaktionen beeinflußt als die Toleranz gegenüber Métolachlor.

Notes: The benzoylarginine peptidase of Treponema denticola (strain ASLM; a human oral spirochaete) was progressively and irreversibly inactivated by 1-(ethoxycarbonyl)-2-ethoxy-1, 2-dihydroquinoline, a carboxyl-group reagent. At acidic pH values, reaction of one mole of the modifier per active site of the enzyme resulted in total inactivation of the enzyme. Assuming that this modifier is a specific carboxyl reagent, the data suggest that the inactivation of the T. denticola benzoylarginine peptidase was caused by the modification of one carboxyl group located close to the active site of the enzyme. Results obtained with Woodward's reagent K (N-ethyl-5-phenylisoxazolium 3’-sulphonate) supported these findings. Carbethoxylation with diethylpyrocarbonate effectively inactivated the enzyme, and addition of hydroxylamine at pH 7.0 restored the activity almost totally, suggesting that the pyrocarbonate had reacted with tyrosyl or histidyl residues.

Notes: 2.5 cm long stem segments of Populus nigra L. did not root when cultured in water or in auxins alone but rooted in glucose. The number of rooted segments and roots produced on them increased with rising glucose concentrations up to 0.5%, but decreased with higher concentrations. An addition of 1.0 mg/1 IAA inhibited rooting at 0.01 % glucose, was ineffective at 0.1 % and stimulative at higher concentrations of glucose which were inhibitory when used alone. The results show that the auxin effects on rooting are influenced by the nutritional status of the stem cutting of a species, and that a proper balance of the two is necessary for root development.

Notes: Abstract— Fracture toughness tests were performed in the ductile-brittle transition temperature range using 110 specimens of the three-point bend and CT types. Probabilistic characteristics of fracture toughness and cleavage crack initiation sites were analysed in detail, together with the fibrous crack shape, from which the plane strain region in the specimen was deduced. The criterion for obtaining plane strain at the mid plane of the specimen was established as: B≤ 0.004{Kc(J)/σy}2+ 0.01. The thickness effect of cleavage fracture toughness for the specimen satisfying this equation is mainly caused by the statistical distribution of the weakest points ahead of the crack front (the Weibull volume effect).

Notes: Abstract— The present study is to investigate the fatigue crack propagation behaviour of surface cracks subjected to combined tension and bending stress. An estimation of fatigue crack growth behaviour employed the Newman-Raju formula before penetration, and a K solution, proposed by the authors, after penetration. Crack length aL at penetration increases with an increase in bending stress. The calculated fatigue crack shape was in good agreement with the experimental shape. It was also found that the crack growth behaviour and the crack shape after penetration can be satisfactorily evaluated using the K solution proposed by the authors.

Notes: Commercial plantations of Java citronella (Cymbopogon winterianus) in Lucknow, Pantnagar and their adjoining areas were affected by a collar rot and wilt disease. The causal organism was identified as Fusarium moniliforme, anamorph of Gibberella fujikuroi. Isolates of the pathogen originating from Lucknow and Pantnagar differed in their pathogenicity on the host plant under glasshouse conditions. There were also differences in growth rates, pigment production and sporulation between isolates.