摘要:

SUMMARYThe action of the herbicidal compound, 4,6‐dinitro‐o‐cresol (DNOC), on rye roots was studied by analyzing its uptake from solutions and subsequent translocation by roots of intact plants and by isolated roots. The distribution of DNOC in the root cells was investigated by differential centrifugation of tissue homogenates.DNOC is readily accumulated and spreads throughout the plant by apoplastic movement. Redistribution hardly occurs.Next to uptake with the transpiration stream there is an intense passive absorption of mainly undissociated molecules. DNOC is partly adsorbed to the walls of xylem vessels and parenchymous cells, partly present in a soluble form. Although adsorption to protein sometimes occurs, DNOC is not metabolized.Soon after the accumulation, unaltered DNOC is released again into the outer solution by a mechanism sensitive to temperature and oxygen tension. The nature of this mechanism, its possible localization and role in detoxification and resumption of growth are disc

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1967.tb00038.x

年代:1967

数据来源: WILEY

摘要:

SUMMARYA histogenetic study of integument development in two juglandaceous genera indicates that in these taxa the integument is formed by both dermal and subdermal cells of the second and third layers of the floral apex (in contradistinction to the exclusively dermal origin recorded in a number of cases). The integument initiates as two individual primordia which coalesce postgenitally to form a circular rim. Subsequently submarginal and subapical initials are formed. After a discussion of the theoretical aspects, the conclusion is drawn that the most plausible explanation of the advent of the inner integument seems to be the so ‐called syntelome hypothesi

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1967.tb00039.x

年代:1967

数据来源: WILEY

摘要:

SUMMARYThe cuticular components cellulose and cutin are decomposed in a period of 3–8 months (depending on the season) by soil microorganisms under natural conditions. The cellulose is attacked prior to the cutin layer. The latter is invaded by microorganisms which settle first in the cellulose layer. If purified cutin strips with the cellulose removed, are exposed to the action of soil microorganisms, the degradation also starts from the “inside” of the layer.The progress of degradation depends on the soil used, active garden soil giving the best, and poor sand soil the slowest attack. The degradation of the cutin layers starts with a swelling of the former boundaries of the epidermal cells, then follows the removal of successive sub‐layers and finally the detachment of entire subunits from the weakened structure, ultimately leading to a total decay of the structure. The detachment of the lamellae within the cutin layer could be shown in cross sections of the exposed material by electron microscopical examination.Halo‐formation around the invading microorganisms, and the lipid accumulation as a result of fatty acid release from the cutin by far‐distance decomposition, showed that cutin decay by exo‐enzyme action is a widespread property of soil m

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1967.tb00040.x

年代:1967

数据来源: WILEY

摘要:

SUMMARYFrom parallel observations on changes in respiration ratein vivoand mitochondrial activityin vitroit is concluded that the respiration of pea cotyledons during germination is mediated by enzymes of the citric acid cycle and of the electron transfer chain. Its course may be divided into four phases. The sharp rise in respiration rate in the first phase is due to activation by hydration of the enzymes of the two systems during swelling. The fairly constant respiration level in the subsequent phase is only to a minor extent due to a limited oxygen supply but primarily to the full hydration of the enzymes of the electron transfer chain present in the air‐dry cotyledons with a certain potential activity. The increase in respiration rate in the third phase is attributed to a rise in activity of the mitochondrial enzymes, whereas the decrease in respiration rate in the fourth phase seems to be due to a disorganization of the subcellular structure of the cotyledon

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1967.tb00041.x

年代:1967

数据来源: WILEY

摘要:

SUMMARYIAA in injuriously high concentrations causes root formation inAvenamesocotyls, which under normal conditions never produce roots.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1967.tb00042.x

年代:1967

数据来源: WILEY