Leaf Litter Extracts Research Articles

Composition and Acidic Functional Group Chemistry of an Aqueous Chestnut Leaf Litter Extract

AbstractThe elemental composition, amino acid distribution, infrared spectrum, and carboxyl group content of a chestnut leaf (Castanea sativa L.) litter extract were determined. Proton titration data also were obtained by both continuous and discontinuous titrations. The overall titration endpoint could be identified directly by conductometric titration. Proton formation functions for the extract were computed from the two sets of titration data. In order to explain protonation during titration, the data were fitted to a simple chemical model by nonlinear regression analysis. From this calculation, the acidic properties of the litter extract could be modeled assuming three classes of acidic functional groups, with logarithms of the conditional protonation constants in the ranges: 4.00–4.25, 6.00–6.75, and 8.7–9.0.

Bound phenolic compounds in water extracts of soils, plant roots and leaf litter

Seven soils were examined for their contents of p-hydroxybenzoic, vanillic, p-coumaric and ferulic acids, p-hydroxybenzaldehyde and vanillin. Water-soluble forms, both “free” and “bound” of the phenolic compounds accounted for less than 0.7% of the total amount of each acid or aldehyde as determined by extraction of the soil with 2 M NaOH. In most instances, more than 50% of the water-soluble compounds were in the bound form, which was estimated after conversion to the free form by treatment of the water extract with NaOH. Water-soluble forms, both free and bound, of each compound also occurred in roots associated with six of the soils, and in beech litter associated with the seventh.

ALLELOPATHIC GROWTH INHIBITION OF NODULATED AND UNNODULATED ALNUS CRISPA SEEDLINGS BY POPULUS BALSAMIFERA

Water extracts of fresh leaves, buds, and leaf litter of Populus balsamifera (balsam poplar) were tested at different dilutions for allelopathic effects on nodulation, nitrogenase activity and growth of nodulated green alder (Alnus crispa) seedlings, and on growth of unnodulated green alder seedlings. All extracts inhibited height growth, root elongation and dry weight increment of nodulated and unnodulated green alder seedlings to some degree during a 2‐month experiment. Foliar nitrogen content of both nodulated and unnodulated seedlings was significantly lower in extract treated plants than in controls. Growth inhibition was about 25% less in nodulated than in unnodulated seedlings. The number of nodules per plant in seedlings treated with any balsam poplar extract was only 51% that of control plants. Acetylene reduction by seedlings treated with bud and leaf litter extracts indicated a decrease of 62% compared to controls. Growth inhibition was not mediated by pH or osmotic effects of the extracts. The possible ecological significance is discussed.

Allelopathic Growth Inhibition of Nodulated and Unnodulated Alnus crispa Seedlings by Populus balsamifera

Water extracts of fresh leaves, buds, and leaf litter of Populus balsamifera (balsam poplar) were tested at different dilutions for allelopathic effects on nodulation, nitrogenase activity and growth of nodulated green alder (Alnus crispa) seedlings, and on growth of unnodulated green alder seedlings. All extracts inhibited height growth, root elongation and dry weight increment of nodulated and unnodulated green alder seedlings to some degree during a 2-month experiment. Foliar nitrogen content of both nodulated and unnodulated seedlings was significantly lower in extract treated plants than in controls. Growth inhibition was about 25% less in nodulated than in unnodulated seedlings. The number of nodules per plant in seedlings treated with any balsam poplar extract was only 51% that of control plants. Acetylene reduction by seedlings treated with bud and leaf litter extracts indicated a decrease of 62% compared to controls. Growth inhibition was not mediated by pH or osmotic effects of the extracts. The possible ecological significance is discussed.

Allelochemic Interference by Quaking Aspen Leaf Litter on Selected Herbaceous Species

Freshly fallen quaking aspen leaf litter incorporated in red clay soil to achieve 2 percent and 4 percent organic carbon resulted in substantial decrease of growth of Festuca elatior, F. rubra, and Poa pratensis compared to growth in unamended and peat amended soils. Lotus corniculatus had limited response differences to these soil additives. The allelochemic response apparently was restricted to early seedling growth as germination of these four species and two other species (Bromus inermis and Lolium perenne) was not affected by leaf litter extracts. The results are consistent with earlier reports of reduced understory growth in aspen stands. The allelochemic potential demonstrated may resuit in a need to develop new aspen forest management plans including crop rotation. Forest Sci. 26:429–434.

Metal Binding Properties of Leaf Litter Extracts: II. A Bioassay Technique

AbstractA biological method is proposed to determine the maximum Cu binding ability and the conditional stability constant of leaf litter extracts. Free cupric ions reduce the 14CO2‐uptake of algae. In the presence of complex forming organic substances the observed depression of the relative CO2 uptake can be considered as a measure of the unbound ionic Cu concentration. Comparing the CO2‐uptake response function of solutions, with and without organic constituents spiked with variable amounts of Cu, yields a functional relationship between bound and free Cu. These functions can be interpreted with a sequential form of the Langmuir equation from which the maximum binding ability and the conditional stability constant are obtained. The presence of algae, modifies the complexing parameters, indicating that the values measured with nonbiological methods require careful interpretation when their significance in natural soils is considered.

Metal Binding Properties of Leaf Litter Extracts: I. Discontinuous Spectrophotometric Titration with Iron and Copper

AbstractA spectrophotometric titration method is proposed with which the maximum Fe or Cu binding ability of leaf litter extracts and the conditional stability constants of the organo‐metallic compounds can be determined. The method was checked against the dialysis method of Zunino and Martin (1977) using Cu as titrant. With Fe instead of Cu the spectrophotometric titration yields also plausible results. In the latter case, however, the results cannot be verified with dialysis experiments because of the colloidal nature of aqueous Fe(OH)3.The distribution between bound and free metal ions can be described by rectangular hyperbolas (Langmuir type regression models). The measurements deviate systematically from the simple Langmuir equation. These deviations can be adequately described if the heterogeneous mixture of dissolved organic constitutents is considered as a system of two independent components with distinct distribution isotherms. The errors involved in the estimation of the conditional stability constants and of the maximum binding abilities are analyzed.

Die Wirkung wäßriger Streuextrakte verschiedener Waldbäume auf Mycelwachstum und Konidiosporenkeimung von Fomes annosus (Fr.) Cke.

Abstract The effect of water extracts of leaf and needle litter from different forest trees on the mycelial growth and the germination rate of conidia of Fomes annosus (Fr.) Cke. Litter extracts from various forest trees and stands have distinct effects on mycelial growth and germination rate of conidia of Fomes annosus. The effects depend on concentration of the extract, period of extraction and on date of collecting the litter samples.

Chemical and bacterial changes in a forest soil percolated with some amino acids and leaf litter extract

Abstract Chemical and bacterial changes in the forest soil percolated with glycine and glutamate solution and leaf litter extract were studied. When the forest soil was percolated with 25 mM glycine or glutamate, it took about 20 days for the number of bacteria to reach the maximum in number and the amino acids to be completely ellhausted, the rate being much slower than that in the cultivated soil. Supplementation of 0.01% yeast extract to the percolate much rnhanced the growth of bacteria and degradation of glycine. In this percolation the metabolic pattern of glycine was comparable to that in the cultivated soil except for the absence of an appreciable amount of nitrate formation. Growth of bacteria in the forest soil was also rapid when percolated with leaf litter extract and only 3 days were sufficient for reaching the maximum number. Neither ammonia nor nitrate was detected throughout the percolation period and only change observed in the solution was a slight rise in pH. Characteristics of bacteria...

Effect of water-soluble organic substances from different types of leaf and needle litter on the downward movement of manganese in sandy soil

Studies were made to know the effect of water-soluble organic substances from different types of leaf and needle litter on the downward movement of manganese in sandy soil. The treatments included teak leaves, bamboo leaves, Casurina needles, Eucalyptus leaves, wild curry leaves, citric acid, glucose solution, and distilled water. The results revealed that the leaf and needle litter extracts as well as citric acid caused movement of manganese but retained it presumably in the form of organo-mineral complex in the upper layers of soil columns compared to that in soil column treated with glucose solution in which case the manganese moved and concentrated in deeper layers due to increased reducing conditions. The column treated with distilled water also showed movement of manganese because the soil texture was sand. re]19730615

THE MOBILIZATION OF IRON BY EXTRACTS OF EUCALYPTUS LEAF LITTER

SummaryWhen aqueous extracts of leaf litter from four closely related Eucalyptus species were reacted with soil material under aerobic conditions their iron mobilizing activity was found to be inversely related to the productivity of the sites on which the species grew. The activity of litter extracts of the four species grown in similar soils in the field was found to increase in the order E. regnans, E. obliqua, E. radiata, E. sieberiana. The results indicate that species‐soil interactions could be as important as inherent species characteristics in determining whether or not a species is a ‘podzol former’.The effect on the activity of the extracts of altering their pH before reaction with either soil or with prepared iron oxides suggests that, whereas organic acids could be mainly responsible for mobilizing iron from soil and from anhydrous ferric oxide, polyphenols could be more important than organic acids in mobilizing iron from hydrous ferric oxide.The pH and Eh curves obtained when litter extracts were titrated with a ferric chloride solution showed that iron from this source was strongly reduced by the extracts at low pH.