Field emergence of Lamium amplexicaule L. and L. purpureum L. in relation to the annual seed dormancy cycle

Seedling emergence of Lamium amplexicaule L. and L. purpureum L. was monitored in field plots tilled at various times during the growing season, and the number of viable seeds in the soil was determined. In plots tilled in early spring, only seeds of L. amplexicaule, germinated, but seeds of both species germinated in the same plots in autumn without further disturbance. Additional seeds of L. amplexicaule, but not of L. purpureum, germinated the following spring. In plots tilled in late spring and summer, seeds of L. amplexicaule germinated in autumn and the following spring, whereas seeds of L. purpureum germinated only in autumn. The number of viable seeds in the top 13 mm layer of soil ranged from 189 to 1216 m^?2 for L. amplexicaule and from 131 to 854 for L. purpureum. These field results support those obtained in previous glasshouse-laboratory physiological studies on the annual dormancy cycle in the two Lamium species. Levée au champ de Lamium amplexicaule L. et L. purpureum L. par rapport au cycle annuel de la dormance des graines La levée de jeunes plants de Lamium amplexicaule L. et L. purpureum L. a été observée sur des parcelles cultivées à différentes époques de la saison de végétation et le nombre de graines viables au sol a été déterminé. Sur les parcelles cultivées en début de printemps, seules les graines de L. amplexicaule ont germé, mais des graines des deux espèces ont germé en automne sur les mêmes parcelles, sans cultivation ultérieure. Au printemps suivant, une nouvelle germination a été constatée chez L. amplexicaule mais pas chez L. purpureum. Sur les parcelles cultivées en fin de printemps et en été, des graines de L. amplexicaule ont germé en automne et aussi au printemps suivant, tandis que les graines de L. purpureum n'ont germé qu'en automne. Le nombre de graines viables dans les premiers 13 mm de la surface du sol allait de 189 à 1216 m^?2 pour L. amplexicaule et de 131 à 854 pour L. purpureum. Ces résultats sur le terrain confirment ceux obtenus dans des études physiologiques sur le cycle annuel de dormance chez les deux espèces de Lamium, menées préalablement en serre et au laboratoire. Ueber dus Auflaufen von Lamium amplexicaule L. und L. purpureum L. in Bezug auf den Jährlichen Zyklus der Samenruhe unter Feldbedingungen In Parzellen, die zu verschiedenen Zeitpunkten während der Vegetationsperiode einer Boden-bearbeitung unterworfen worden waren, wurde sowohl das Auflaufen der Keimlinge von Lamium amplexicaule L. und L. purpureum L. registriert, als auch die Anzahl lebenfähiger Samen festgestellt. Nach Bodenbearbeitung im frühen Frühling keimten nur Samen von L. amplexicaule; im Herbst keimten in denselben Parzellen jedoch Samen beider Arten, sofern der Boden nicht mehr bewegt worden war. Weitere Samen von L. amplexicaule, nicht aber von L. purpureum, keimten im folgenden Frühling. In Parzellen, die im späten Frühling und im Sommer bearbeitet worden waren, keimte L. amplexicaule im Herbst und im folgenden Frühling. Während L. purpureum nur im Herbst keimte. Die Anzahl lebensfähiger Samen m^?2 in den obersten 13 mm des Bodens bewegte sich zwischen 189 und 1216 für L. amplexicaule und zwischen 131 und 854 für L. purpureum. Diese Feldresultate bestätigen Ergebnisse von Gewüchshausstudien über den jährlichen Zyklus der Samenruhe der beiden Lamium-Arten.     

Temperature requirements for after-ripening in seeds of nine winter annuals

Temperature requirements for after-ripening were investigated in seeds of the weedy winter annuals Arabidopsis thaliana, Arenaria serpyllifolia, Capsella bursar-pastoris, Cardamine hirsuta. Cerastium viscosum, Draba verna, Holosteum umbellatum, Stellaria media and Thlaspi per-foliata. Fresh seeds of seven species were innately dormant, and those of A. serpyllifolia and C. viscosum were conditionally dormant. (Dormancy terminology follows Vegis, 1964.) Seeds of each species were buried in moist soil at 5, 15/6, 20/10, 25/15, 30/15 and 35/20°C from time of maturation in spring until the third week of September. Buried seeds at each temperature were then exhumed and tested in light at all six temperatures. Seeds of all species became non-dormant at 25/15, 30/15 and 35/20°C, except for those of D. verna, H. umbellatum, A. serpyllifolia and C. viscosum, which rotted during burial at 35/20°C At 20/10°C. seeds of T perfoliata and D. verna became conditionally dormant, and those of the other seven species became non-dormant. Thalaspi perfoliata and D. verna seeds did not after-ripen at 5 or 15/6°C, while those of H. umbellatum and C. hirsuta became conditionally dormant at 15/6°C but remained innately dormant at 5°C. The other five species became conditionally dormant at both 5 and 15/6°C; they germinated at low, bill not at high, temperatures. Thus, after-ripening in seeds of winter annuals is fully promoted by high summer temperatures and wholly or partially inhibited by low winter temperatures. Exigences en temperature pour la post-maturation des semences de neuf espèces annuelles d'hiver Les exigences en température pour la post-maturation ont étéétudiées chez les semences d'adventices annuelles d'hiver, Arabidopsis thaliana, Arenaria serpyllifolia, Cupsella bursa-pastoris, Cardamine hirsuta, Cerastium viscosum, Draba verna, Holosteum umbellatum, Stellaria media et thlaspi perfaliata. Les semences fraîches de sept espèces manifestaient une dormance absolue, et celles de A. serpyllifolia et C. viscosum une dormance relative (selon la terminologie de Vegis, 1964). Des semences de chaque espèce ont été enfouies dans du sol humide à 5, 15/6, 20/10, 25/15, 30/15 et 35/20°C, à partir de la période de maturation au printemps et jusqu'à la troisième semaine de Septembre. Les semences enfouies aux différentes températures ont été ensuite exhumées et soumise, sous éclairement, aux six conditions de température. Les semences de toutes les espèces ont perdu leur dormance à 25/15, 30/15 et 3/20°C, excepté celles de D. verna. H. umbellatum, A. serpillyfolia et C. viscosum, qui ont pourri après a voir été enfouies à 35/20°C. A 20/10°C, les semences de. T. perfoliata et D. verna ont acquis une dormance relative et celles des sept autres espèces sont devenues non dormantes Les semences de Thlaspi perfoliata et D. verna n'ont pas subi de post-maturation à 5 ou 15/6°C, alors que celles de H. umbellatum et de C. hirsuta ont acquis une dormance relative à 15/6°C mais ont conserveé une dormance absolue à 5°C. Les cinq autres espèces ont acquis une dormance conditionnelle à la fois à 5 et 15/6°C; elles ont germéà basse, mais non à haute température. Par consèquent, la post-maturation des semences d'annuelles d'hiver est totalement induite par les fortes tempéeratures d'été, et totalement ou partiellement inhibée par les basses températures d'hiver. Temperaturhedürftnisse zur Nachreifung von Samen bei neun Winterannuellen In dieser Studie wurden die Temperaturanor- derungen zur Nachreifung der Samen der winter-annuellen Unkräuter Arabidopsis thaliana, Arenaria serpyllifolia, Capsella bursa-pastoris, Cardamine hirsuta, Cerasthim viscosum, Draba verna, Holosteum umbellatum, Stellaria media und Thlaspi perfoliata untersucht. Junge Samen von sieben Arten sind von Natur aus obligat und diejenigen von A. serpyllifolia und C. viscosum je nach Umständen dormant (Terminologie der Samenruhe nach Vegis, 1964). Samen jeder Species wurden zur Zeit der Samenreife im Frühling in feuchtem Boden eingegraben und darin bei Temperaturen von 5, 15/6, 20/10, 25/15, 30/15 und 35/20°C bis zur dritten Woche im September belassen. Danach wurden die Samen ausgegraben und unter Lichleninfluss bei allen sechs Temperaturstufen auf ihre Keimfähigkeit getestet. Mit Ausnahme der Samen von D. Verna, H. umbellatum, A. serpyllifolia und C. viscosum, welche bei 35/20°C im Boden verfault waren, wurden alle anderen Arten bei 25/15, 30/15 und 35/20°C keimfähig. Bei 20/10 °C kamen die Samen von T. perfoliata und D. verna in einen bedingten Ruhezustand, während diejenigen der anderen sieben Arten voll keimfähig wurden. T. perfoliata und D. verna reiften bei 5 oder 15/6°C nicht nach: H. umbellatum und C. hirsuta wurden bei 15/6 °C bedingt keimfähig, blieben aber bei 5°C völlig dormant. Die anderen fünf Arten erreichten bei 5 und 15/6°C eine bedingte Dormanz; sie keimten bei niedrigen, nicht aber bei hohen Temperaturen. Aus diesen Ergenissen lässt sich schlicssen, dass die Nachreifung von Samen winterannueller Arien durch hohe Sommertemperaturen voll entwickelt, durch niedrige Wintertemperaturen aber ganz oder teilweise gehemmt wird.     

Temperature requirements for after-ripening in buried seeds of four summer annual weeds

Freshly matured, seeds of the four summer annuals Ambrosia artemisiifolia, Polygonum pensylvanicum, Amaranthus hybridus and Chenopodium album were buried in soil at (12/12 h) daily thermoperiods of 15/6, 20/10, 25/15, 30/15 and 35/20°C and at a constant temperature of 5°C. After 0, 1, 3 and 5 months, seeds of each species at each temperature were exhumed and tested at a 14-h daily photoperiod at all six temperatures. Fresh seeds of A. artemisiifolia and P. pensylvanicum did not germinate at any temperature, those of A, hybridus germinated to 4 and 64% at 30/15 and 35/20°C, respectively, and those of C. album to 11–20% at 25/15, 30/15 and 35/20°C. Seeds of A. artemisiifolia and P. pensylvanicum, which germinate only in spring, required exposure to low (5, 15/6°C) temperature to after-ripen completely (i.e., to gain the ability to germinate over a wide range of temperatures), and little or no after-ripening occurred at high (25/15, 30/15 and 35/20°C) temperatures. Seeds of A. hybridus and C. album, which germinate in spring and summer, required exposure to low temperature to after-ripen completely, but at high temperatures they rapidly gained the ability to germinate at high temperatures. Regardless of the burial temperatures and species, when after-ripening occurred, seeds firs germinated at high and then at low temperatures. The minimum germination temperature for a species decreased with after-ripening temperature and with an increase in the length of the burial period.     

Role of temperature in regulating timing of germination in soil seed reserves of Lamium purpureum L.

Fresh seeds of Lamium purpureum L. were dormant at maturity, and when buried and exposed to natural seasonal temperature changes they exhibited an annual dormancy/non-dormancy cycle. During burial in summer, fresh seeds and those that had been buried for 1 year afterripened and thus were non-dormant by September and October; light was required for germination. During autumn and winter seeds re-entered dormancy, and during the following summer they became non-dormant again. Dormant seeds afterripened when buried and stored over a range of temperatures, becoming conditionally dormant at low (5, 15/6°C) and non-dormant at high (20/10, 25/15, 30/15 and 35/20°C) temperatures. Conditionally dormant seeds germinated to high percentages at 5, 15/6 and 20/10°C, while non-dormant seeds germinated to high percentages additionally at 25/15, 30/15 and 35/20°C. Low temperatures caused non-dormant seeds to re-enter dormancy, while high temperatures caused a sharp decline in germination only at 30/15 and 5°C. The temperature responses of L. purpureum seeds are compared to those of L. amplexicaule L.     

A contrast radiographic study of the vagina and uterus of the normal bitch

A method is described for investigating radiographically the shape of the bitch's vagina. The intra-pelvic vagina is readily dilated whereas the intra-abdominal vagina is narrow and tortuous, and cranially is typically ‘spoon-shaped’. Contrast medium entered the uterus during pro-oestrus, oestrus and the post-partum period, indicating patency of the cervix at these times. No cervical relaxation was evident at the end of the luteal phase, i.e. during anoestrus. The possible relevance of these findings to the aetiology of pyometra is discussed.     

Electron microscopical study of a new genus and new species of microsporida in the gills of Atlantic cod Gadus morhua L.*

Abstract. A microsporidium, forming xenoparasitic complexes (xencmas) of the cell-hypertrophy tumour type, was found in the gills of the Atlantic cod Gadus morhua L. and studied with the electron microscope. It seemed to be similar to Nosema branchiate Nemeczek, 1911, in the haddock Melanogrammus aeglefinus (L.) except in size of spore. The xenoma (cyst) was basically like the Glugea cyst and the parasite had some other characters in common with Glugea; it was apansporoblastic, unikaryotic, disporoblastic and underwent partial development in parasitophorous vacuoles. It differed from Glugea in lacking plasmodial stages, producing usually 1 or 2 spores (rather than 16) in a vacuole, showing no distinct tendency for different stages to occur in different zones of the cyst and having tubules in the parasitophorous vacuoles. The name Loma morhua n. g., n. sp. (type) was proposed and the genus assigned to the family Glugeidae Thélohan, 1892. The parasite of haddock gill was transferred to the new genus, becoming L. branchialis (Nemeczek, 1911) n. comb.     

Loma salmonae (Putz, Hoffman and Dunbar, 1965) in the rainbow trout, Salmo gairdneri Richardson, and L. fontinalis sp. nov. (Microsporida) in the brook trout, Salvelinus fontinalis (Mitchill)

Abstract. Loma salmonae (Putz, Hoffman and Dunbar, 1965), Morrison & Sprague, 1981, in the rainbow trout, Salmo gairdneri Richardson, was studied with the electron microscope. It is morphologically very similar to L. morhua Morrison and Sprague, 1981, in the Atlantic cod, Gadus morhua L., having only minor differences. Loma sp. Morrison and Sprague, 1981, in the brook trout, Salvelinus fontinalis (Mitchill), is more like L. salmonae than the other species of Loma , but was deemed to be distinct. It was named L. fontinalis sp. nov.