摘要:

SUMMARYAnatomical investigation showed that callus cultures ofPopulus nigraL. cv. ‘Italica’ contain lignified parenchyma cells and that large amounts of lignin are localized in intercellular spaces. A tissue‐culture strain on a medium containing IAA also showed differentiation of tracheids with lignified walls.In the plant, lignin was found in the primary xylem, secondary xylem, phloem, and periderm. The lignin from primary xylem gave a negative Mäule reaction.Lignins from callus cultures and from the plant were compared and quantitatively determined.A method was developed to calculate the lignin content of tissues from the lignothioglycolic acid yield and the absorption at 250 nm in the so‐called difference spectrum.Oxidation with nitrobenzene yielded syringaldehyde (S) and vanillin (V) from tissue cultures, young and old secondary xylem, phloem, and periderm; primary xylem gave vanillin but no syringaldehyde.For tissue cultures, young secondary xylem, phloem, and periderm, the S/V ratio is lower than for differentiated wood. For 2,4‐D cultures the S/V ratio was lower than for a strain cultured on an IAA medium.The aldehyde yield, calculated as a percentage of the lignin, is appreciably higher for secondary xylem (42%) than for phloem, periderm, and tissue cultures (12–18%).Xylem lignin contains 9–10% esterifiedp‐hydroxybenzoic acid. Less of this acid is found in the lignin of young secondary xylem (5.2%) and the tissue cultures (2.8–6.7%). Phloem lignin has a still lowerp‐hydroxybenzoic acid content (0.6%).Lignin rich inp‐hydroxybenzoic acid is characterized by a very high absorption in the difference spectrum at 296 nm, strong absorption in the infrared spectrum at 1265 cm‐1, and an extra absorption band at 766 cm‐1. After hydrolyzation, this lignin lacks the 766 band in the IR spectrum and shows much less absorption at 1265 cm–1.Alkali lignin was prepared by a 16‐hour extraction with 0.5 N NaOH at 70 °C. Complete extraction of the lignin from the tissue samples was rarely obtained.Lignin preparations deriving from the various tissue regions of the plant and from the callus cultures show mutual differences. The lignin of the callus cultures shows the greatest resemblance to the lignin of young secondary xylem but is much more resistant to oxidation. In this respect it shows a closer relationship to the lignin from the phloem and primary xylem of the tree.The terms “angiosperm lignin” and “hardwood lignin” applied to a lignin with a high syringaldehyde content are very misleading, because not all the lignified tissues of dicotyled

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00150.x

年代:1969

数据来源: WILEY

摘要:

SUMMARYThe distribution of air‐borne salt in a distinctly zonated coastal dune area has been investigated by means of 27 simple measuring instruments, placed in 4 transects, perpendicular to the coastline: two in a northwest‐southeastern line, the other two in a southwest‐northeastern line.The pattern of distribution proved to be determined by wind velocity, distance from the sea, wind direction, height above N.A.P. and shelter by surrounding vegetation. Most salt was deposited during high wind velocities. The influence of rainfall was difficult to establish because periods of high rainfall usually coincide with those of high winds.It is stressed that the income of nutrient elements from sea‐spray is only half of the significance of air‐borne salt as a contributor to the gradient system of the dune environment. For the existence of gradients in space and time and thus for biological diversity the leaching by rain and any other decrease of these elements is just as

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00151.x

年代:1969

数据来源: WILEY

摘要:

SUMMARYThe present paper, the first of a series of four on the biosystematics of the Dutch halophilous species ofSpergularia, reports the results of a study of the morphological variability ofS. mediaby means of a number of population samples from all parts of the Dutch area, supplemented by the rearing of plants from seed samples in the experimental garden.The seeds ofS. mediaare usually winged, but in the area of the Dutch North Sea Islands, sometimes populations are encountered containing up to 70% plants with exalate to subalate seeds.The development of the seed wing is chiefly determined by genetic factors, but to some extent modifiable by different environmental conditions. The seed wing is too variable to be of decisive diagnostic value to distinguishS. mediafromS. marina. Plants with exalate to subalate seeds produce seedlings that are significantly smaller than the seedlings of plants with broadly winged seeds. Fruit‐ and calyx lengths vary too widely to be of diagnostic value either.The number of stamens plus staminodes is usually 10, rarely 9; the number of fertile stamens is 8 to 10 in nearly all flowers of a population, but may be as low as 0 to 3 per flower in some individual plants. The number of fertile stamens is primarily determined by genetic factors. The growth habit and the vegetative characters appear to exhibit only phenotypic variatio

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00152.x

年代:1969

数据来源: WILEY

摘要:

SUMMARYThe effect of lipase and protease action on the low‐temperature fluorescence spectra of spinach chloroplast fragments is described and the results are discussed. Attempts to fractionate chloroplast fragments treated with the hydrolytic enzymes into the two photochemical systems of photosynthesis were unsuccessfu

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00153.x

年代:1969

数据来源: WILEY

摘要:

SUMMARYIt will be demonstrated that the formation of the purple pigment in a mixture of catechol, proline and a crude enzyme preparation cannot be accepted as a qualitative test for polyphenoloxidase activity as proposed by Drawert&Gebbing(1963).

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00154.x

年代:1969

数据来源: WILEY

摘要:

SUMMARYIn the hypocotyl of dark‐grown gherkin seedlings a series of maxima in the level of phenylalanine deaminase (PADAse), a key enzyme in phenol synthesis, can be induced by an alternating light‐dark treatment. Each PADAse peak corresponds to a temporary increase in the rate of accumulation of hydroxycinnamic acids. The height of a particular enzyme peak is a function of the length of the inducing light period and of the light sensitivity of the plant at the time of irradiation. The light sensitivity is inversely related to the amount of hydroxycinnamic acids that have previously accumulated in consequence of preceding irradiation. Possible implications of these findings on the problem of biological time measurement are discus

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00155.x

年代:1969

数据来源: WILEY

摘要:

SUMMARYThe activities of hexokinase, phosphoglucomutase, phosphoglucoisomerase, glucose‐6‐phosphate dehydrogenase and 6‐phosphogluconate dehydrogenase have been determined in the tissue at various distances from the wounded or inoculated surface of potato tuber halves after 1 or 2 days of incubation. Phosphoglucomutase activity was very high when compared to hexokinase activity, and is probably present in great excess. Phosphoglucoisomerase was 3 times as active as glucose‐6‐phosphate dehydrogenase which was about 4 times as active as 6‐phosphogluconate dehydrogenase. The enzyme activities in healthy tissue and their changes when metabolism was activated by wounding or infection, suggest that the increase of carbohydrate dissimilation and of the pentose phosphate pathway operation might not primarily be governed by the amounts of enzymes in the tissue. The possible role of the nicotinamide adenine nucleotides in the regulation of carbohydrate dissimilation i

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00156.x

年代:1969

数据来源: WILEY

摘要:

SUMMARYA study was made on the effect of soil water stress on transpiration, photosynthesis, stomatal aperture and relative turgidity of coffee plants.The decrease in turgidity as a consequence of soil moisture depletion was only small, due to the closing of stomatas and hence a decrease in transpiration. This means that an efficient water control is present in coffee plants. The reduction in photosynthesis, however, was much more pronounced than that in transpiration. This could be ascribed, apart from an increase in stomatal resistance, to the large effect of increasing leaf temperature on the internal CO2concentration. The diurnal variation in stomatal resistance and internal CO2concentration shows that at midday with a moderate soil moisture stress a closure of stomates results in a decrease in CO2internal. Net photosynthesis almost recovers in a period of five days when rewatering after drought.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00157.x

年代:1969

数据来源: WILEY

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00158.x

年代:1969

数据来源: WILEY

摘要:

SUMMARYThis paper contains a discussion of the taxonomic subdivisions of theRubiaceaeas proposed by Schumann, Verdcourt, and Bremekamp. Generally speaking, the subdivisions as proposed and delimited by Bremekamp agree best with the characters of the wood structure, as observed by the author. Furthermore a key to the Suriname genera is given.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1969.tb00159.x

年代:1969

数据来源: WILEY