摘要:

SUMMARYPositive photoblastic seeds ofChenopodium albumneed the action of the active form (Pfr) of phytochrome (P) during nearly the total length of the overall germination process. The first Pfr dependent processes require a Pfr/P ratio above the level being present in darkness. The different requirement for the length of the red irradiation indicates that these first processes have a different Pfr requirement in the individual seeds of one population. Simultaneous irradiations with narrow wavelength bands of red (643 nm) and far‐red (768 nm) light, which established different Pfr/P ratios, supported this conclusion. The Pfr requirement is a function of the thickness of the seed‐coat.The germination of half operated seeds (the outer seed‐coat layer is removed in the area overlying the radicle) can be induced by the dark level of Pfr, being approximately Pfr/P = 0.07.The required Pfr level for the germination processes after the escape from the antagonistic effect of short far‐red irradiations, decreases from 0.07 to below 0.02. Osmotic stress increases the Pfr requirement. Prolonged irradiations with far‐red light inhibit the germination processes when they are already in the phase of the embryo elongation. The elongation process is supposed to consist mainly of cellular expansion. The process which induces the secondary photodormancy is only related to the first Pfr dependent

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00651.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYThe egg and central cell ofPetunia hybridaundergo a number of changes and become mature during anthesis. The egg greatly enlarges and becomes highly vacuolated. The nucleus and the major part of the cytoplasm of the mature egg are located at the chalazal pole of the cell. The number of organelles decreases slightly during maturation. The ribosomes of the mature egg are clustered in polysomes. The chalazal part of the mature egg seems to be surrounded by the plasma membrane only, whereas the remainder of the cell has a normal cell wall.The number of mitochondria and plastids and the amount of endoplasmic reticulum (ER) in the central cell are almost constant during maturation. The number of ribosomes, however, increases greatly. Almost all ribosomes are free and the impression is that they are monosommes. A large amount of starch is formed in the plastids. Two types of dictyosomes are present in the mature central cell. The outer membranes of the polar nuclei are sometimes connected by ER membranes.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00652.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYA new species of the genusSesquicilliumW. Gams is described and figured. It differs from the other two known species by very small conidia produced in heads.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00653.x

年代:1970

数据来源: WILEY

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00654.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYA study was made of the occurrence of iridoid glycosides (giving a colour reaction with anisidine) in theScrophulariaceae. Aucuboside, catalpol and antirrhinoside were found in many species: in addition some hitherto unknown, presumably iridoid glycosides were found. Most tribes were homogeneous as to the types of glycosides present, while the subfamilies were not.On the basis of the prevailing glycosides the family can be segregated into the following groups:taxa devoid of glycosides (mostGratioleae, theCalceolarieae, mostDigitaleae, Sphenandra, Suterap.p., andNemesia).taxa containing aucuboside and (or) catalpol (Verbasceae, Scrophularieae, Collinsieae Hemiphragmeae, Buchnereae, Veroniceae, Rhinantheae, Suterap.p.,Limosella, Mazus, Zaluzianskya, Angelonia, Diascia, Erinus, andRehmannia).taxa containing antirrhinoside (Antirrhineae).theSelaginoideaewith unidentified glysosides.The generaLeucocarpus, Halleria, andAlonsoahave aberrant, but presumably iridoid glycosides, and therefore do not fit in any of the groups mentioned.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00655.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYCarpospores isolated fromHalymenia floresiagametophytes collected at Banyuls (France, Pyrénées Orientales) grew intoAcrochaetium‐like plants. ThisAcrochaetiumphase was capable of reproduction by monospores. Some of theAcrochaetium‐like plants thus obtained differentiated intoHalymeniasporophytes that produced monospores from monosporangial sori, and no tetrasporangia. These monospores developed intoAcrochaetium‐like or disciform plants, from some of which differentiated newHalymeniagametophytes.Carpospores isolated fromHalymenia floresiagametophytes collected at Rovinj (Yugoslavia) grew intoAcrochaetium‐like plants. ThisAcrochaetiumphase was capable of reproduction by monospores. Some of theAcrochaetium‐like plants thus obtained differentiated intoHalymeniaplants that reproduced firstly by means of gemmae and secondly by the formation of “apical pompons” from necrotic apices. “Apical pompons” wereAcrochaetium‐like plants grown from islands of living cortical cells lying amidst necrotic tissues. No new gametophyticHalymeniaplants were obtained in cultures of Rovinj material, and therefore in culture the life‐history was not completed.Vegetative isolates (from cortical filaments) of Rovinj gametophytes grew intoAcrochaetium‐like plants reproducing by monosporulation. TheseAcrochaetiumplants were not able to redifferentiate intoHalymeniaplants. Three types of such gametophyticAcrochaetiumphases, differing in growth form and intensity of monosporulatio

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00656.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYIn homogenates of pea roots only one protein complex is responsible for the degradation of IAA. It consists at least of two enzymes which are probably intimately associated. This protein complex possesses an isoelectric point of 9.5 and has only a small net charge at neutral pH. At least 3 other peroxidases are present with a similar range of molecular weight as commonly displayed by the IAA degrading protein. Probably these enzymes are also bound to membranes.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00657.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYLeaf temperatures of tropical rain forest plants, weeds, crops, as well as temperate beach and dune plants, were measured by contact with fine ribbon thermocouples and by a non‐contact thermal radiation method. With strong solar radiation, non‐transpiring leaves (covered with vaseline) in the tropics usually have temperatures of more than 10 °C above air temperature. Temperature differences of up to 20 °C were measured. The highest temperature differences leaf‐air of temperate plants are only a few degrees centigrade below those of tropical plants. The temperatures of fresh leaves (both tropical and temperate) may vary in full sunshine from somewhat below air temperature to virtually the same temperature as the vaseline covered leaf.The question was asked whether the strong transpiration cooling observed on leaves ofSaccharum officinale, Calotropis giganteaandPhragmites communisand the extreme transpiration cooling (13 °C below air temperature) observed by Lange in the Sahara had to be explained by special properties of the leaf or rather by the dryness of the atmosphere.From the temperature measurements on the leaves and the vapour pressure of the air it is possible to calculate a factor n which is the ratio of the total resistance of the leaf to water loss and the external resistance. For weeds and production crops typical values of n are between 3 and 6. Similar values were found for the sclerophyllousEryngium maritimumand forAster tripolium. For some species a high n (>50) seems to be normal. The data indicate that strong transpiration cooling is not due to an abnormally low water loss resistance but to the extreme dryness of

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00658.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYA study was made of the photoperiodic induction of flowering inLemna minor, strain 6573. For comparison some experiments were performed withL. gibba.Like the latter,L. minor, strain 6573, proves to be a typical long‐day plant. The critical daylength is about 10.5 hrs in a 24 hrs cycle, the response being, however, very weak. Much better responses are obtained with photoperiods of 13 and 14 hrs (from 25 to 30 per cent flowering). The response to a 13 hrs photoperiod shows a peculiar rhythm in the rate of development of flowers with periods of slow development alternating with periods of rapid development. A possible relation of this phenomenon to the observed rate of multiplication is discusse

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00659.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYA new species ofAlternaria, A. phragmospora, is described and illustrated. Observations on the fungus are recorded and a comparison withAlternaria raphaniGroves and Skolko is made.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00660.x

年代:1970

数据来源: WILEY