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Copyright of Weed Research is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Weed Research is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A ring-hydroxylated metabolite was produced by excised oat, barley, and corn roots from phenoxy-n-aliphatic acids, acetic through hexanoic, which possessed an even number of carbons in the side chain. Peanut, soybean, and alfalfa roots did not show this activity. Paper chromatographic and ultra-violet spectral data indicated that the metabolite was 4-hydroxyphenoxyacetic acid. There was no evidence for production of hydroxylated products of longer chain length. This suggests ring hydroxylation may have followed β-oxidation of the side chain. The greater hydroxylation activity of the relatively resistant gramineous species as compared to the susceptible legumes is compatible with the suggested role of hydroxylation as a detoxication reaction. [ABSTRACT FROM AUTHOR]

1. A method bas been worked out with phosphate buffer, pH 7.2, for the extraction of auxins and growth inhibitors from maize kernels. 2. The content of free and bound acid auxin in maize kernels is greatest in unripe maize and decreases in connection with the maturation of the kernels. 3. Four different growth stimulators have been found in the acid fraction of ether extracts of maize kernels of different degrees of swelling. On chromatographing in isopropanol-ammonia-water these have the following Rf values: a, 0-0.1; b, 0.2-0.4 (IAA); c, 0.5-0.8 and d. 0.8-1.0. Inhibitors have been detected with the Rf values 0.1, 0.5 and 0.8-1.0. 4. Two growth-stimulating substances, e and f. have been found in the neutral fraction of phosphate buffer extracts. Their Rf values in different solvents have been determined (see Table 4). In chromatographing f forms partly another substance, g, e is easily converted into a mixture of f and g, All three substances exhibit a reaction with Ehrlich s reagent and therefore they all are probably indole compounds. They also react with ninhydrin. Paper chromatography has shown that f is identical with tryptamine (see Figures 9 and 10). e and g have not been identified. f has also been found in ether extracts. 5. e apparently constitutes an intermediary link between IAA and inactive IAA precursors. [ABSTRACT FROM AUTHOR]

The present paper deals with some aspects on the geotropic response of higher plants, on the auxin-induced potentials in Zea Mays and also on connections between these effects which could not a priori he assumed to exist. The main results are summarized in the following: 1. The logarithmic stimulus-response relation is found to regulate geotropical bending of Avena coleoptiles al 22.5° and 10.0°C and with forces in the region 0.2 to 12.5 times the gravitational force. 2. The reciprocity rule is valid for Avena at 22.5°C, while measurements at 10.0°C. do not clearly support this rule. 3. Investigating the geoelectric effects on Zea Mays at different temperatures and forces gave the expected polarity (the "under" side of the coleoptile positive with respect to the "upper"). At all temperatures and with all forces the existence of a latency period is confirmed. It is shown by varying force and temperature that the latency time for Zea Mays may be separated into two parts, one of which has a Q10, indicating a chemical reaction. The second part of the latency time has been used to test the reciprocity rule. This is strongly supported for Zea mays in the force region 0.2-12.5 g at 10.0, 22.5 and 30.0°C. 4. To explain the presentation times two theories are examined the first of which is the ordinary "sedimentation of statoliths" theory, the second based upon Brownian movements. [ABSTRACT FROM AUTHOR]

This article focuses on the paper "Essential Fatty Acids, Degree of Unsaturation and Effect of Corn (Maize) Oil on the Serum-Cholesterol Level in Man," by Ancel Keys, J.J. Anderson and Francisco Grande that was published in a 1957 issue of the periodical "Lancet." Substituting carbohydrate for the common meat can lower the serum cholesterol level in man and dairy fat in the diet and this does not depend on the intake of cholesterol itself. Different fats vary in their effect and certain vegetable oils may depress the serum cholesterol. Corn (maize) oil has been found particularly effective and it has been suggested on the one hand that its effect depends on the degree of unsaturation of the constituent fatty acids, and on the other that it depends on the amount of the essential fatty acid, linoleic acid.

The intra-cellular localization of the herbicide N,N-dimethyl-2,2-diphenylacetamide (diphenamid) was examined in 10 mm root tips of corn seedlings (Zea mays L. cv. Shawnee). Experiments are described which culminate in the observation. that a significant, measurable effect on root growth occurs within 12 hours after treatment with diphenamid. Corn seedlings were then treated with 14-C-diphenamid for 12 hours and the 10 mm root tips excised and homogenized. By use of differential centrifugation and gel filtration, the root homogenate was separated into fractions as follows; cell wall, mitochondria, microsomal, protein and eluate. The highest concentration of the herbicide was found in the root tips. Furthermore, most of the radioactivity was found in the eluate. Results are discussed as to localization of diphenamid in the microsomal and protein fraction and possible mode of action. [ABSTRACT FROM AUTHOR]

A "quasi-diffusion resistance", rq' is defined to accommodate the role which the thermochemical and photochemical phenomena of photosynthesis play in the control of CO2-fixation to the terminology and approach of the diffusion resistance analogue for the CO2 exchange of leaves. The relationship of rq to Rabinowitch's classical rectangular hyperbolic model of photosynthesis rate as a function of CO2-concentration at the carboxylating surface is discussed. Examination of KmnPP for phos- Phopyruvate carboxylase (the predominant carboxylase in maize) suggests, as a reasonable hypothesis for light-saturated maize leaves, that rq may be essentially independent of ambient CO2-concentration up to at least 300 μI/I. A corollary of the hypothesis is that an increase of diffusion resistance, rather than of rq, may account for the observed curvature of the response curves of light-saturated maize leaf photosynthesis to ambient CO2-concentration. An experiment carried out on fieldgrown maize plants, using a well controlled leaf chamber as a nitrous oxide diffusion porometer, gave evidence which strongly supported the hypothesis. [ABSTRACT FROM AUTHOR]

This article reports that the pigment deficiency of albino corn seedlings is due to an extreme light sensitivity of albino tissues. The pigment destruction is an oxidative process. The increased light sensitivity may be explained by the abnormal carotenoid composition of the albino tissues. Studies on the effect of selective enzyme inhibitors on the carotenoid content direct our attention to the probable role of copper enzymes in the synthesis of carotenoids. The activity of cyanide-sensitive enzymes in albino leaves is decreased upon illumination and this might affect the connection between dehydrogenases and the synthesis of leaf pigments.

This paper provides a detailed analysis of bird damage assessments to detect crop loss in corn. Measurement criteria, methods of loss calculation, and rate of sampling are discussed. In planning a strategy to measure crop loss, one needs to take into account distribution of damage as well as variation in measurement.

Copyright of Weed Research is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Exudation from the xylem of excised maize roots was studied in roots bathed in solutions containing kinetin or abscisic acid (ABA). Kinetin reduced the water permeability of the roots whilst ABA increased it. The action of both hormones was reversible and both were effective at concentrations of 10-6M and below. The possible in vivo role of these two hormones is discussed. [ABSTRACT FROM AUTHOR]

The effect of Endogone infection on the stem anatomy and on the reproduction in tomato, maize, strawberry and petunia was examined. In tomato, petunia and maize plants, the infection increased the amount of vascular tissue. The lignification of the xylem was greater in mycorrhizal tomato and petunia plants and more vascular bundles were produced in the maize plants. Mycorrhizal infection stimulated flower production in petunia, the formation of fruit in strawberry and the development of pollen in maize. [ABSTRACT FROM AUTHOR]

Stacking of chloroplast lamellae, isolated from normal and carotenoid mutant chloroplasts of maize (Zea mays L.), was determined after a high‐salt treatment. Stacking of isolated lamellae under favourable ionic conditions was almost identical with that occurring in intact chloroplasts; thus, differences in granum content could be attributed to the architectural properties of lamellae. Gaussian analyses, performed on the red band of room temperature absorption spectra, have shown that chloroplasts with lamellae of high stacking capacity contain relatively more Chl a662 than chloroplasts containing lamellae of low stacking capacity. The presence of Chl a705–708 was characteristic of preparations containing considerable amounts of stroma lamellae. [ABSTRACT FROM AUTHOR]

The postulate that single roots of Zea mays transport their absorbed phosphorus nonuniformly to the leaves was tested. Plants were grown under growth chamber conditions for three to four weeks in nutrient solution. At this stage of growth a series of plants was placed into a system in which two roots on each plant were allowed to absorb either 33P or 32P from uptake solutions for time intervals of up to 24 hours. Plants subsequently were harvested such that each leaf was partitioned into samples containing tissue from one side or the other of the midrib. All samples were assayed for 33P and 32P and the results were expressed as the amount of total P transported into different plant parts from a single root. Nonuniform P accumulation in the leaves occurred and different patterns of accumulation, dependent on the type of root chosen for uptake were observed. Nearly uniform P accumulation occurred between one side and the other of a given leaf when transport was from radicle roots. In marked contrast, transport from adventitious roots resulted in an alternating pattern of accumulation between one side and the other of each successive leaf up the stem. The seminal root system supplied more P to the older leaves than did the adventitious root system. The nature of these nonuniform P transport patterns is attributed to the vascular organization between roots and leaves. [ABSTRACT FROM AUTHOR]