Autoradiography was used to determine the distribution of labeled sugar in conducting elements of the blade and petiole of sugar beet leaves at intervals ranging from 5 sec to 24 hr. The processes of assimilation by the green cells, collection of sugar in the minor veins and export in phloem elements were demonstrated visually. It appears that in minor veins sugar is translocated in companion c...

Tis study examined the nest architecture, colony productivity, and duration of the immature stages of the social wasp Mischocyttarus consimilis Zikán (Hymenoptera: Vespidae). The study was carried out under field conditions. Nests of M. consimilis consist of a single uncovered comb, which is attached to the substratum by a single petiole. The data for the nest architecture showed a positive and...

The current controversy about the "cohesion-tension" of water ascent in plants arises from the recent cryo-scanning electron microscopy (cryo-SEM) observations of xylem vessels content by Canny and coworkers (1995). On the basis of these observations it has been claimed that vessels were emptying and refilling during active transpiration in direct contradiction to the previous theory. In this s...

The photosynthetic assimilates in leaves of Perilla crispa attached to the plant were labeled by treating the leaves with (14)CO(2). When subsequently detached, these leaves exuded a negligible amount of radioactivity from the cut petiole into water. Ethylenediaminetetraacetate (EDTA), citric acid, and ethyleneglycol-bis (beta-aminoethyl ether) N,N'-tetraacetate greatly increased exudation of l...

Nitrogen fertilizer applications, for maximum fertilizer efficiencies and crop yields, should be based on the N required by the crop during its various growth stages. The objectives of this paper were to identify the N requirements of the potato plant (Solarium tuberosurn L.) during growth and to evaluate selected soil and plant tissue tests as indicators of the plant's N status. Growth analysi...

The ascorbate-glutathione (ASC-GSH) cycle has an important role in defensive processes against oxidative damage generated by drought stress. In this study, the changes that take place in apoplastic and symplastic ASC-GSH cycle enzymes of the leaf and petiole were investigated under drought stress causing leaf rolling in Ctenanthe setosa (Rose.) Eichler (Marantaceae). Apoplastic and symplastic e...

Grapevines are crops of global economic importance that will face increasing drought stress because many varieties are described as highly sensitive to hydraulic failure as frequency and intensity of summer drought increase. We developed and used novel approaches to define water stress thresholds for preventing hydraulic failure, which were compared to the drought stress experienced over a deca...

Extracts of style, petal, leaf, petiole, stem, and callus derived from stems of wild tomato (Lycopersicon peruvianum) contain characteristic sets of arabinogalactan-proteins. This is demonstrated by crossed electrophoresis in which Yariv reagent, which specifically binds to and precipitates arabinogalactan-proteins, is incorporated into the second gel.

The present controversial status of the problem of transport rate as related to temperature is briefly summarized in a recent paper by WENT and HULL (8). As pointed out by these authors, the reported Qlo values for translocation range from less than 1 (7, 8), to essentially 1 (5), to values greater than 1 (3, 4). The effects of temperature are multiple and greatly complicate an analysis of this...

The distribution of lead (Pb) accumulated in the pteridophyte Blechnum niponicum, a Pb-hyperaccumulator, was measured using synchrotron-radiation micro X-ray fluorescence (SR-micro-XRF) at BL37XU of SPring-8. From two-dimensional (2D) imagings of Pb at the root, petiole, leaf vein, pinna epidermis and sorus in the Blechnum niponicum, the mechanism for the transportation and accumulation of Pb c...