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Evidence for the presence of abscisic acid (ABA) in the perennial root nodules of Alnus glutinosa (L.) Gaertn. has been obtained by electron-capture-detection gas chromatography (GC-ECD), combined gas-chromatography mass spectrometry (GC-MS) and GC-MS using single-ion monitoring (GC-SIM). The free-ABA content of the nodules was shown by GC-ECD analysis to fluctuate seasonally over the range 101 to 879 ng g[SUP-1] fresh weight. No obvious correlations were found between the amount of ABA detected and rates of nodule growth. However, ABA pools in dormant nodules were up to 2.5 times higher than in those from actively growing plants. [ABSTRACT FROM AUTHOR]

Rates of photosynthesis and acetylene reduction by whole plants were measured on (a) twelve Alnus glutinosa clones and (b) A. glutinosa seedlings grown in low and high irradiances. Both genetic and environmental manipulation of photosynthetic rates produced concomitant changes in rates of acetylene reduction. Far the clonal material, growing under closely similar environmental conditions, mean rate of net photosynthesis was significantly positively correlated with both the mean fresh weight of nodules formed per plant and with the mean rate of acetylene reduction. [ABSTRACT FROM AUTHOR]

The possible effects of applied indole-acetic acid upon ntirogenase activity and respiration in alder nodules could not be distinguished form the effects of the manipulative procedures themselves. The extent to which plants were handled during the acetylene reduction assay had a large inhibitory effect upon the apparent nitrogenase activity of the nodules. [ABSTRACT FROM AUTHOR]

The content of gibberellin-like (GA-like) substances in various parts of young alder (Alnus glutinosa (L.) Gaertn.) plants was estimated by means of the lettuce hypocotyl bioassay. The highest levels of GA-like activity were found in the root nodules, of dormant plants, plants emerging from dormancy, and plants in full leaf. No major differences were found in the roots and leaves of nodulated as opposed to nonnodulated plants, although the stems of nodulated plants did contain lower levels of GA-like activity. The detection of seasonal changes in GA-like activity in root nodules from mature trees was dependent upon the method of chromatography employed. One major peak of biological activity was detected following paper chromatography and no large changes were detected in the level of this component. In contrast, three zones of GA-like activity could be detected after thin layer chromatography (TLC) and there were marked seasonal changes in activity in these three zones. This can be attributed either to changes in levels of the GA-like substances themselves and/or to variations in the amounts of impurities interfering with the response of the bioassay. A number of peaks of GA-like activity were detected by lettuce and rice bioassays following analysis of a large-scale extract on a preparative high performance liquid chromatograph (HPLC). However, both the total number and the identity of the substances responsible for this activity, remain to be determined. [ABSTRACT FROM AUTHOR]

Citrulline was the major amino acid in root pressure sap, stem sap and stem wood from Alnus glutinosa L. Gaertn, plants relying on fixed nitrogen or, partly or wholly, on mineral nitrogen for growth. Glutamine increased in prominence in plants assimilating mineral nitrogen but asparagine remained, a relatively insignificant component. Differences in the relative amounts of the free amino compounds of stem sap from nitrogen-fixing and mineral nitrogen-fed plants were usually small compared to differences between plants fed different sources of mineral nitrogen. In contrast, relatively high values for the ratios of citrulline/total free amino nitrogen compounds and particularly of citrulline/amides in root pressure sap distinguished nitrogen-fixing plants from those receiving mineral nitrogen. Although the amino acid ratios of stem wood extracts showed closer similarity to those for root pressure sap than stem sap, the seasonal accumulation of citrulline, possibly as a storage amino acid, in stem wood from field-grown plants negated the possibility of utilising stem wood analyses as an indicator of the form of nitrogen assimilation. Comparative data on the levels of citrulline or other free amino acids in Alnus glutinosa are unlikely to be useful as an index of nitrogen fixation, under most experimental conditions. [ABSTRACT FROM AUTHOR]

The principal polyamines in Alnus glutinosa roots, nodules and root pressure sap, putrescine, spermidine and spermine, were quantified by reversed-phase, high-performance liquid chromatography with fluorescence detection following precolumn derivatization with 9-fluorenylmethyl chloroformate and 1-ada-mantanamine. Pressure was the major component of all tissues and sap. It comprised 70% or more of the polymine pool except in roots of KNO3-fed plants, in which similar amounts of putrescine and spermidine were present at levels five-fold lower than plants fed (NH4)2SO4. However, the polyamine content of root pressure sap from nodulated plants increased almost four-fold when they were fed with increasing concentration of NH4NO3, although the total polymine content remained low (>5 mmol m-3 sap). The polyamine content of the Alnus root system changed with plant age. In particular, the spermidine content of both roots and nodules was higher in 10- as compared to 16-week-old plants. [ABSTRACT FROM AUTHOR]

The translocation of [sup14]C-labelled photosynthate to the nodules of first-year alder plants growing under natural illumination, but at constant temperature, is shown to be a rapid process which results in a maximum influx of new photosynthate at the time of the mid-day peak in fixation. Analysis of fluctuations in the levels of the main free sugars present in the nodules at different times of day, and a study of the effects of interrupting supplies of photosynthate to the root system by stem ringing, suggests that a substantial part of the nodule carbohydrate is unavailable for fixation and that maximal rates of fixation are only attained when new photosynthates are entering the nodules in quantity. No evidence was obtained for an autonomous element in the mid-day maximum in fixation when plants were kept in continuous darkness; a fall in acetylene reduction to an insignificant level 24 hours after darkening was accompanied by a fall in nodule sugars -- notably in the amount of sucrose present. The rate of acetylene reduction by nodulated roots reached a maximum at about 25° C, and, at this temperature, was some six times faster than at 15° C. [ABSTRACT FROM AUTHOR]