ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00562.x

年代:1969

数据来源: WILEY

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00563.x

年代:1969

数据来源: WILEY

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00564.x

年代:1969

数据来源: WILEY

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00565.x

年代:1969

数据来源: WILEY

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00566.x

年代:1969

数据来源: WILEY

摘要:

SUMMARYA survey is given of the present state of the theory of symplasmic transport. The symplasmic movement of organic and inorganic substances inVallisnerialeaves shows polarity. The polarity is not a stable factor of the tissue, since it can be changed in different ways. Data regarding the movement of auxin inVallisnerialeaves have been compared with data about auxin transport in coleoptiles. Attention has been given to the localisation and the function of the plasmodesmata. The conclusion is arrived at that there are two fluxes in coleoptiles, a longitudinal flux which uses the plasmodesmata in the transverse walls and a transverse flux which uses the plasmodesmata in the longitudinal walls.Movement in the symplasm is caused by concentration differences in combination with electric potential gradients and by gravity. Active transport requires the maintenance of these potential gradients by cell metabolism. The forces presumably influence the transit of the substances through the plasmodesmata, from cell to cell.At a cut surface cells are opened and substances are released to the exterior. The exit of auxin at the basal wound surface is the consequence of the continuous polar movement of auxin through the plasmodesmata in the transverse walls of the cells and the opening of the adjoining cells by cutting. The movement of endogenous and exogenous auxin are different.Endogenous auxin is moved by electric potential gradients in the tissue and by gravity, while exogenous auxin is moved by the same factors and moreover by the concentration difference which is the result of the active uptake of auxin in the symplasm.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00567.x

年代:1969

数据来源: WILEY

摘要:

SUMMARYYoung seedlings ofZea maysL. scarcely grow at temperatures of 15 °C or lower. The leaves are yellowish, the chlorophyll concentration being lower than 10μg (a+b) per cm2, and the rate of photosynthesis is negligible. When a period of low temperature is given to older plants, which already have some green leaf surface, the reduction in relative growth rate and photosynthesis is less severe. Only those leaf parts that elongate during the cold treatment are yellow.It can be shown that the day temperature is the important factor in influencing the chlorophyll concentration in growing leaf parts. Plants subjected to low night temperatures remain fully green and their growth rate is virtually unaffected. The data suggest that photosynthesis rate is reduced at concentrations of chlorophyll (a+b) below 40μg per cm‐2. When plants are brought back to temperatures of 20 ° or higher both photosynthesis rate and growth rate soon reach values normal for this temper

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00568.x

年代:1969

数据来源: WILEY

摘要:

SUMMARYA case of twin nucelli in an ovule ofPterocarya fraxinifolia, originated from a cleavage of the nucellus primordium and presumably representing a hitherto unrecorded type of polyembryony inJuglandaceae, is discussed. The qualification of this category of polyembryony as “false polyembryony” according to the conventional classification of Ernst is unsatisfactory. A new system of classification of polyembryony is propo

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00569.x

年代:1969

数据来源: WILEY

摘要:

SUMMARYThe foliar uptake and subsequent transport in bean plants of22Na,32P and134Cs was studied under controlled environmental conditions but at varying root temperatures. The amounts taken up by the plants, held in the treated areas, distributed in various plant fractions or excreted through the roots were determined for periods of up to 6 days. Uptake of22Na was found to be slower than that of134Cs and much faster than that of32P. Root temperature strongly influenced the rate of entrance of the isotopes with an optimum range between 20 and 25 °C. The penetration was found to be more affected by the root temperature during the pretreatment period than by that during the experimental period itself. The translocation and distribution during the first 6 hours of the experimental periods were also influenced by the pretreatment temperature of the roots. Na and Cs leakage in the solution was found to occur at all temperatures, provided transport had allowed their presence in the root tissues

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00570.x

年代:1969

数据来源: WILEY

摘要:

SUMMARYDiploid chromosome numbers are reported in species of the Papilionaceous generaGamwellia, Bolusia, Argyrolobium, Adenocarpus, Trifolium, Rhynchosia, andEriosema, all of them, except one, originating from the African continent. Some notes are added discussing the taxonomic significance of these numbers.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00571.x

年代:1969

数据来源: WILEY