Chloroplast Pigments Research Articles

Effect of Morpholine Systemic Fungicides on the Chloroplast Pigments of Wheat and Maize

Abstract The growth, chlorophyll and carotenoid contents of wheat and maize seedlings as influenced by a soil drench of 250 μM of tridemorph or fenpropimorph, were studied. It was found that the length of the shoot, primary leaf, and root, as well as the leaf area were significantly reduced in the fungicide treated seedlings. Although the dry matter percentage was higher in the treated seedlings as compared to the control, the fresh or dry weight per shoot remained lower in the fungicide treated seedlings. The chloroplast pigments in the treated seedlings of both crops were unaffected, suggesting that the fungicides had no significant effect on the chlorophyll or carotenoid biosynthesis.

Effect of paclobutrazol on growth, chloroplast pigments and sterol biosynthesis of maize ( Zea mays L.)

Growth, chlorophyll, carotenoid and sterol biosynthesis in maize seedlings as influenced by soil drenches of 30, 60 and 90 μM paclobutrazol were studied. The growth regulator delayed seedling emergence and retarded vegetative growth, but increased the dry matter percentage. However, the fresh and dry weight per shoot remained lower in paclobutrazol treated seedlings than in control seedlings. The chloroplast pigments determined per unit fresh or dry weight were not significantly affected by either levels of paclobutrazol, although the treated seedlings appeared more green than the control seedlings. Both chlorophyll and carotenoid concents per leaf were decreased but the chlorophyll concentration per unit leaf area was enhanced by paclobutrazol. This was due to the concentration of the decreased amount of chlorophyll into much smaller leaf area, and indeed the biosynthesis of chloroplast pigments was unaffected by paclobutrazol. Paclobutrazol affected the 14-demethylation and second alkylation reactions in phytosterol biosynthesis but not enough to be phytotoxic.

Role of pulvinar chloroplasts in light-driven leaf movements of the trifoliate leaf of bean (Phaseolus vulgarisL.)

Laminar pulvini of bean (Phaseolus vulgaris L.) contain numerous chloroplasts in cells of their motor tissue. The quantitative relationships of the chloroplast pigments, chlorophyll a and b, β-carotene, lutein, neo-xanthin as well as the xanthophyll cycle carotenoids (violaxanthin, antheraxanthin and zeaxanthin) were similar to those of mesophyll chloroplasts from leaflet laminae. Exposure of pulvinules to light caused de-epoxidation of violaxanthin to zeaxanthin, showing that the xanthophyll cycle is functioning. Chlorophyll fluorescence analysis of pulvinules confirmed that their chloroplasts are capable of both photosynthetic electron transport and non-photochemical fluorescence quenching, showing that they build up a considerable transthylakoid proton gradient in the light. Application of DCMU to excised pulvinules and laminar discs, as well as to pulvinules of intact, attached terminal leaflets blocked electron transport and fluorescence quenching. Application of the uncoupler CCCP to intact pulvinules also prevented non-photochemical fluorescence quenching. The rate of movement of the low-light-adapted terminal leaflet in response to exposure of its pulvinule to overhead red light (500 μmol m -2 s -1 ) was reduced when the pulvinule was pretreated with DCMU. The pulvinar response to overhead blue light (50 μmol m -2 s -1 ), which is more pronounced than to red light, was not affected by similar pretreatment with DCMU. Pretreatment with CCCP caused a short lag in the response to red light, but did not affect its subsequent rate. The results suggest that the pulvinar response to red, but not to blue light, requires non-cyclic electron transport and the resulting generation of ATP.

Nuclear Mutations Affecting Chloroplastic Pigments of Photoperiod‐insensitive Barley

AbstractThree photoperiod‐sensitive spring barley cultivars (Hordeum vulgare L.) and three independently derived, single‐gene, nuclear mutants expressing photoperiod insensitivity and extremely early heading time under short daylengths were investigated for chloroplastic pigment variation in three environments using reverse‐phase high‐performance liquid chromatography (HPLC) to account for differences in laminae colour. In a greenhouse, non‐stress environment and in a full sunlight, high‐temperature stress environment, no systematic differences were observed among pigments of the mutant‐parent pairs. However, under 12 h of daily light (600 μE m 2sec−1) and stress temperatures (20/10°C, night/day) in a growth chamber, the three mutants appeared similar to each other in chlorotic appearance and laminae pigment contents, but differed from the three non ‐chlorotic parents, which were similar to each other. The mutants had less chlorophyll a and b, β‐carotene, lutein, taraxanthin, violaxanthin, and neoxanthin but more zeaxanthin than their parents. When shaded, the mutants became less chlorotic. How phenotypic differences for heading time and perception of day‐length might be related to altered chloroplast contents remains unclear. The single‐gene mutants conferring photopenod insensitivity were more sensitive to photothermal stress than their photoperiod‐sensitive counterparts and as a result, their zeaxanthin content increased but the level of other pigments decreased.

Effects of metribuzin herbicide on nitrogen, pigments, protease and nitrate reductase activity of normal and NaCl-stressed castor bean and maize plants

Addition of 0.5 and 2.5 gm-3 of metribuzin into Hoagland nutrient media, either alone or in combination with NaCl, induced significant decreases in nitrate-, amino-, ammonia-, and total soluble-N contents, whereas significant increases in these nitrogen fractions were apparent in maize and castor bean seedlings and plants treated with high concentrations (5 and 10 g m-3) of the herbicide, again either alone or in combination with NaCl. Protein- and total-N contents increased and decreased at low and high concentrations of the herbicide, respectively. The contents of chlorophyllsa andb, as well as carotenoids of both castor bean and maize seedlings and plants treated with low concentration of herbicide, either alone or supplemented with NaCl, were unaffected, whereas at high concentrations of the herbicide a significant decrease in chloroplast pigments was found. Nitrate reductase activity (NRA) was increased significantly at low concentrations of the herbicide alone and decreased significantly at high levels. Inclusion of NaCl into the herbicide media induced significant decreases in NRA of both castor bean and maize seedlings and plants. Unlike NRA changes, protease activity was increased significantly with high concentrations (5 and 10 g m-3) of metribuzin and decreased significantly with its low (0.5 and 2.5 g m-3) concentrations.

The Vertical Pattern of Pigment Concentrations in Chloroplasts of Sphagnum capillifolium

The concentrations of chloroplast pigments were determined in current-year tissues of Sphagnum capillifolium (Ehrh.) Hedw. harvested at the end of the growing season in a bog in the southern Alps of Italy. Concentrations of both chlorophylls were highest in the midsummer segment. Concentrations of carotenoids were fairly stable, except in the spring segment, whereas chlorophyll derivatives (pheophytin, pheophorbide, and chlorophyllide) accumulated in the top segment, corre- sponding to the autumnal capitulum. This indicates a rapid degradation of chlorophyll, probably caused by nightly chilling, at the end of the growing season.

The Stimulating Effect of a Cold Dark Pretreatment on the Accumulation of Components of Light‐Harvesting Chlorophyll a/b Complexes and on Photosynthetic Activity in Wheat (Triticum aestivum)

AbstractRecently we reported on the stimulating effect of a cold dark pretreatment (cold‐dp) on the chlorophyll accumulation (Schönbohm et al., 1988) and on the CO2‐ and O2‐gas exchange (Schönbohm and Czeska‐Werner, 1990) during de‐etiolation of wheat leaves under white light.The goal of the present paper was to study the effect of a cold‐dp on the accumulation of chloroplast pigments, on the kinetics of fluorescence quenching, on the synthesis of Cab‐proteins and on the amounts of cab‐transcripts during de‐etiolation under white light.The following results were obtained: Not only the chlorophyll synthesis but also the synthesis of xanthophylls and of β‐carotene is highly increased by a cold‐dp. The kinetics of the PAM‐fluorescence curves demonstrate that the activity and co‐operation of the two photosystems start earlier and with higher efficiency during de‐etiolation in cold‐dp than in warm‐dp wheat leaves. The amount of cab‐transcripts can be elevated by a cold‐dp. The amount of Cab‐proteins during de‐etiolation is much higher in cold‐dp than in warm‐dp wheat leaves. The presented data are in accordance with our earlier published results. Consequences of these results on seedlings growing under natural conditions with fluctuating temperatures during day and night are pointed out.

Further observations on the Mg-protoporphyrin IX monomethyl ester (oxidative) cyclase system.

The Mg-protoporphyrin IX monomethyl ester (oxidative) cyclase was strongly inhibited by CN- and N3- in a reconstituted system, but was inhibited slightly or not at all by the same reagents in intact developing chloroplasts. Known inhibitors of cytochrome P-450 processes showed no consistent effect. Benzoquinone and quinol, which can give rise to the same semiquinone by one-electron redox events, were strong inhibitors of the cyclase. It was previously shown that O2 and a source of electrons are required in the cyclization process. The substrates for the dehydrogenases of the pentose phosphate pathway (glucose 6-phosphate and 6-phosphogluconate) were effective reductants in the reconstituted system with supernatant that had been dialysed or passed through Sephadex G-50, in the absence of added NADP+. However, inhibitor studies suggested that the electrons from these sugar phosphates reached the cyclase system via NADPH. Therefore we infer the presence of protein-bound NADP+ that can be reduced by glucose 6-phosphate and 6-phosphogluconate and donate reducing equivalents to the cyclase system. This bound NADPH pool may be particularly effective in the cyclization process, owing to channeling. These findings are discussed in relation to the results of a companion paper [Whyte and Castelfranco (1993) Biochem. J. 290, 361-367] on the breakdown of chloroplast pigments in the same reconstituted system.

Growth of cotton under continuous salinity stress: influence on allocation pattern, stomatal and non-stomatal components of photosynthesis and dissipation of excess light energy

Cotton (Gossypium hirsutum L.) plants were grown in flowing-culture solutions containing 0%, 26% and 55% natural seawater under controlled and otherwise identical conditions. Leaf Na(+) content rose to 360 mM in 55% seawater, yet the K(+) content was maintained above 100 mM. The K(+)/Na(+) selectivity ratio was much greater in the saline plants than in the control plants. All plants were healthy and able to complete the life cycle but relative growth rate fell by 46% in 26% seawater and by 83% in 55% seawater. Much of this reduction in growth was caused by a decreased allocation of carbon to leaf growth versus root growth. The ratio of leaf area/plant dry weight fell by 32% in 26% seawater and by 50% in 55 % seawater while the rate of carbon gain per unit leaf area fell by only 20% in 26% seawater and by as much as 66% in 55% seawater. Partial stomatal closure accounted for nearly all of the fall in the photosynthesis rate in 26% seawater but in 55% seawater much of the fall also can be attributed to non-stomatal factors. As a result of the greater effect of salinity on stomatal conductance than on CO2-uptake rate, photosynthetic water-use efficiency was markedly improved by salinity. This was also confirmed by stablecarbon-isotope analyses of leaf sugar and of leaf cellulose and starch. - Although non-stomatal photosynthetic capacity at the growth light was reduced by as much as 42% in 55% seawater, no effects were detected on the intrinsic photon yield of photosynthesis nor on the efficiency of photosystem II photochemistry, chlorophyll a/b ratio, carotenoid composition or the operation of the xanthophyll cycle. Whereas salinity caused in increase in mesophyll thickness and content of chloroplast pigments it caused a decrease in total leaf nitrogen content. The results indicate that the salinity-induced reduction in non-stomatal photosynthetic capacity was not caused by any detrimental effect on the photosynthetic apparatus but reflects a decreased allocation to enzymes of carbon fixation. - Rates of energy dissipation via CO2 fixation and photorespiration, calculated from gas-exchange measurements, were insufficient to balance the rate of light-energy absorption at the growth light. Salinity therefore would have been expected to cause the excess excitation energy to rise, leading to an increased nonradiative dissipation in the pigment bed and resulting increases in non-photochemical fluorescence quenching and zeaxanthin formation. However, no such changes could be detected, implying that salinity may have increased energy dissipation via a yet unidentified energy-consuming process. This lack of a response to salinity stress is in contrast to the responses elicited by short-term water stress which caused strong non-photochemical quenching and massive zeaxanthin formation.

Different Illumination Dependent Behaviour of Chloroplast Ultrastructure in the Gall and Leaf Tissues of Zelkova serrata ‘Aurea’

Summary The chloroplasts in the parenchyma tissue of the galls on Zelkova serrata 'Aurea' leaves do not react to variations of light intensity by any remarkable ultrastructural changes, like those of the neighbouring leaf tissue. Both chloroplasts of the galls on green leaves, grown in the shade, as well as those on the yellow, sun-exposed leaves, contain a well developed thylakoid system with a high stacking degree of its membranes. The content of chloroplast pigments corresponds well to these facts. The possible cause for such behaviour of the gall parenchyma chloroplasts is discussed.

Temperature treatments of dark-grown pea seedlings cause an accelerated greening in the light at different levels of gene expression.

We have previously shown that heat-shock in the dark evokes photomorphogenesis-like effects and circadian rhythmicity at the level of mRNAs when applied to emerging pea plantlets during several consecutive days [15]. Here we extend these findings by showing that a temperature shift to 10 degrees C above average and a single heat-shock are sufficient for induction of circadian rhythmicity and changes in morphogenesis. The maximum response to a single heat-shock occurs at days 2 to 3 after sowing indicating additional developmental control of the response. An increasing number of heat-shock treatments intensifies the morphogenetic effect. The heat-shocked plantlets have an elevated level of the xanthophyll lutein in the dark. Upon illumination of heat-shocked plantlets accumulation of chloroplast pigments as well as that of individual thylakoid membrane proteins and their corresponding mRNAs occur much faster than in the etiolated controls. This is reflected in an accelerated formation of grana stacks. Therefore, heat-shock seems to evoke a responsiveness of plantlets similar to that obtained earlier by other authors using pre-illumination. The working hypothesis is put forward that induction or synchronization of circadian rhythmicity by either light or heat-shock might be sufficient to explain the observed morphogenetic changes.

EFFECT OF CYTOZYME ON SEED GERMINATION, EARLY SEEDLING GROWTH AND CHLOROPLAST PIGMENTS CONTENT IN CERTAIN PULSE CROPS

While the lower concentrations of cytozyme promoted seed germination, seedling growth, fresh and dry weights and chloroplast pigments content in pigeonpea, cowpea and soybean, the higher concentrations inhibited seed germination as well as seedling growth, Cytozyme if applied at a concentration of 2 ml/ as a seed soaking medium might improve both seed germination as well as seedling growth in pulse crops to the maximum extent.

Photoinhibition of photosynthesis under natural conditions in ivy (Hedera helix L.) growing in an understory of deciduous trees

We investigated to what extent south-exposed leaves (E-leaves) of the evergreen ivy (Hedera helix L.) growing in the shadow of two deciduous trees suffered from photoinhibition of photosynthesis when leaf-shedding started in autumn. Since air temperatures drop concomitantly with increase in light levels, changes in photosynthetic parameters (apparent quantum yield, Φ i and maximal photosynthetic capacity of O2 evolution, Pmax; chlorophyll-a fluorescence at room temperature) as well as pigment composition were compared with those in north-exposed leaves of the same clone (N-leaves; photosynthetic photon flux density PPFD< 100 μmol · m(-2) · s(-2)) and phenotypic sun leaves (S-leaves; PPFD up to 2000 μmol · m(-2) · s(-1)).In leaves exposed to drastic light changes during winter (E-leaves) strong photoinhibition of photosynthesis could be observed as soon as the incident PPFD increased in autumn. In contrast, in N-leaves the ratio of variable fluorescence to maximum fluorescence (FV/FMm) and Φ i did not decline appreciably prior to severe frosts (up to -12° C) in January. At this time, Φ i was reduced to a similar extent in all leaves, from about 0.073 μmol O2 · μmol(-1) photons before stress to about 0.020. Changes in Φ i were linearly correlated with changes in fv/fm (r = 0.955). The strong reduction in FV/FM on exposure to stress was caused by quenching in FM. The initial fluorescence (F0), however, was also quenched in all leaves. The diminished fluorescence yield was accompanied by an increase in zeaxanthin content. These effects indicate that winter stress in ivy primarily induces an increase in non-radiative energy-dissipation followed by "photoinhibitory damage" of PSII. Although a pronounced photooxidative bleaching of chloroplast pigments occurred in January (especially in E-leaves), photosynthetic parameters recovered completely in spring. Thus, the reduction in potential photosynthetic yield in winter may be up to three times greater in leaves subjected to increasing light levels than in leaves not exposed to a changing light environment.

Decoloration of vegetable oils and oleoresins with recovery of unaltered pigments

AbstractThe present study confirms that N,N‐dimethylformamide for the extraction of chloroplast pigments from vegetable tissues shows no differences from the usual acetone or methanol. Therefore, it can be applied to fats, as it allows separation of lipids and pigments by means of phase distribution between light petroleum ether and N,N‐dimethylformamide. The ether phase retains the decolored fatty matter, and the pigments dissolved in N,N‐dimethylformamide can be recovered totally unaltered.This method has been applied to oleoresins and oils from different products and origins. Satisfactory results have been obtained in terms of the degree of decoloration and the percentage of oil recovered. At the same time, the unaltered pigment concentrate obtained from the hypophase could be used as a color enhancer in the chemico‐pharmaceutical industry.

The Meiobenthos Along a Mediterranean Deep‐Sea Transect off Calvi (Corsica) and in an Adjacent Canyon

Abstract. Meiobenthos densities (excluding hard‐shcllcd foraminifcrans) were compared along a Mediterranean deep‐sea transect off Calvi (Corsica) and in an adjacent canyon. Chloroplastic Pigment Equivalent values (CPE) provided an estimate of the amount of primary production reaching the bottom.The stations along the transect were characterized by a low CPE content of the sediment, decreasing with increasing station depth. CPE values in the canyon were much higher, which probably resulted from import of material from the adjacent bay of Calvi. Similarly, meiobenthos densities along the transect were much lower than at comparable depths along the canyon.Meiobenthos density was significantly and positively correlated with CPE values.Nematodes were the most abundant taxon at all stations, followed by copepods + nauplii and the soft‐shelled foraminiferans. The meiobenthos was most abundant in the upper half centimeter. Nematode and foraminiferan densities tended to decline less rapidly with increasing depth into the sediment. Specimens belonging to the recently described phylum Loricifera, larvae of the parasitic crustacean class Tantulocarida, and fragments of an infaunal Xenophyophoria (large protozoans) are reported for the first time from the Mediterranean.

The Fate of Chloroplast Pigments during Senescence of Primary Leaves of Hordeum vulgare and Avena sativum

Summary The fate of chloroplast pigments during senescence of detached primary leaves of Hordeum vulgare L. and Avena sativum L. has been studied. In both species, the carotenoids were lost at a much slower rate than the chlorophylls, with chlorophyll a being lost at a slightly faster rate than chlorophyll b. A detailed examination of the pattern of carotenoid destruction by high performance liquid chromatography revealed, however, that different processes were taking place in the two species. In H. vulgare , β-carotene levels were reduced to approximately 40 % of their original levels whereas the xanthophylls (lutein, violaxanthin and neoxanthin) were reduced to between 8 % and 16 % of their original levels. Violaxanthin and neoxanthin were particularly susceptible to the oxidative processes involved in senescence. In A. sativum lutein was the most stable carotenoid and both neoxanthin and β-carotene were readily destroyed. In both species quite high levels of xanthophyll acyl esters, accounting for up to 60 % of total carotenoid, were detected in the leaves, especially in the late stages of senescence. Plastoglobuli isolated from H. vulgare contained equivalent amounts of unesterified lutein and β-carotene together with small amounts of xanthophyll acyl esters. Chlorophylls were present in only trace amounts in the plastoglobuli. Similar patterns of pigment destruction were seen in detached leaves and intact seedlings.

The Effects of a Hydrogel Polymer on the Growth of Certain Horticultural Crops under Saline Conditions

The effects of incorporating a hydrogel polymer into sand on the development of selected horticultural plants grown under saline conditions has been demonstrated. In separate experiments, the seeds of tomato (Lycopersicon esculentum Mill.), lettuce (Lactuca sativa L.) and cucumber (Cucumis sativus L.) were germinated in sand/swollen hydrogel polymer mixture (25:75, v:v) with added Hoagland nutrient solution. At cotyledon + first true leaf stage, the plantlets were transplanted into polythene growbags containing a range of sand/swollen hydrogel polymer combinations (0:100, 25:75, 50:50, 75:25 and 100:0, v:v). Saline solutions containing NaCl, CaCl2 and MgCl2 were prepared as molar solutions and applied at combined concentrations as follows; Control (Hoagland), 2000, 4000, 8000, and 32 000 ppm. Application of the appropriate solution to the growbags was made twice per week, alternating with a comparable watering regime. Harvesting was carried out after 14 and 28 d. Polymer incorporation encouraged growth of all species under all saline conditions, the order of effectiveness of the polymer contents being as follows; 75%>50%>25%>100%>0%. At high salinity (32 000 ppm) plants of the test species were reduced in growth but appeared to be tolerant at all levels of polymer incorporation; in pure sand the level of tolerance in tomato and cucumber was < 8000 ppm and in lettuce <4000 ppm. Generally, dry weight, leaf area, succulence, chloroplast pigments (chlorophyll a, chlorophyll b, and carotenoids), photosynthetic activity, total amino acids, proline, and protein contents were increased with polymer incorporation compared with pure sand. This hydrogel polymer appears to be highly effective for use as a soil conditioner in horticulture, to improve crop tolerance and growth in a sand or light gravel substrate under saline conditions. It is intended to confirm the results of these studies by field trials.

Resolution of lutein and zeaxanthin using a non-endcapped, lightly carbon-loaded C 18 high-performance liquid chromatographic column

A new rapid and reproducible high-performance liquid chromtographic method using Spherisorb ODS-1, a non-endcapped, lightly carbon-loaded column material, for the separation of higher-plant chloroplast pigments is described. The method resolves lutein and zeaxanthin, as well as all other major and most minor pigments at or near baseline by either of two solvent programs. Program I is faster and more sensitive than program I while the latter resolves pheophytin a and β,ε-carotene slightly better than program I. Both programs use an inital buffered aqueous mixture that apperas critical for this application of ODS-1. The method is well suited for analysis of xanthophyll-cycle pigment changes.

Quantitative distribution of deep-sea meiobenthos in the northwestern Mediterranean (Gulf of Lions)

The distribution of metazoan meiofauna abundances, in relation to environmental factors and “food indicators”, was examined in 29 surface sediment samples taken between 672 and 2367 m in five canyons on the northwestern Mediterranean margin in summer and autumn 1986. Almost all the parameters measured decreased significantly, with increasing water depth. Meiofauna densities were dominated by nematodes (92.4%), and ranged from 36 to 1005 individuals 10 cm −2. They were positively correlated with sediment water content (30–70%), organic carbon (2.7–7.8 mg g −1) and nitrogen (0.3–1.1 mg g −1) concentrations, chloroplastic pigment levels (0.35–8.29 μg g −1) as well as viable bacterial counts [9 × 10 −3 −3 × 10 −5 Colony Forming Units (CFU) ml −1], and microbial total uptake (5.8–50.6% after 4 h) and respiration (2.3–19.0%) of 14C-glucose. They were only poorly or were not correlated with sediment granulometry (56.7–97.0% < 40 μm), total microbial uptake (7.1–51.0% after 4 h) or respiration (2.0–24.0%) of 14C-glutamic acid. Principal Component Analysis was used to describe and evaluate associations of parameters and samples. The quantitative distribution of meiofauna along the margin is well reflected by the distribution of “food indicators”; this can be explained by “distance from land masses” and “water depth”. In the Gulf of Lions, meiofaunal abundance decreases more rapidly with increasing depth than in other oceans, because the margin includes two different systems: (1) the upper slope, which is comparatively rich and active due to continental and coastal (high primary productivity) influence, related to rivers that induce downslope transport of organic-rich fine sediment; (2) the lower slope and basin mainly fuelled by the low offshore productivity, combined with relative high degradation rates in the warm (13°C from 100 m, to the seabed) waters. The comparison of summer and autumn samples revealed the existence of temporal variability (meiofauna abundances doubled from summer to autumn over the entire area), related to seasonal inputs of organic matter into the benthos.

An analysis of needle yellowing in healthy and chlorotic Norway spruce(Picea abies) in a forest decline area of the Fichtelgebirge(N.E. Bavaria)

In a forest decline area (Fichtelgebirge, N.E. Bavaria, FRG), annual time courses of chloroplast pigments in both healthy and chlorotic Norway spruce were studied. The seasonal time courses of green and apparently healthy trees did not generally differ from those reported in the literature for spruce trees of other regions. Chlorophyll content increased from May to October, remained relatively constant or declined slightly during the fall and early winter, and finally decreased markedly from March to early May when pigment is at its minimum before bud break. The annual maximal chlorophyll content increased with needle age from the current year's needles to 4-yearold needles. While carotene content reached its highest concentration in August, the xanthophylls did not peak until February or March. Pigment dynamics of chlorotic trees with lower concentrations, corresponded to those of undamaged trees. Chlorophyll deficits resulted from less pigment formation as well as pigment loss during the growing period. Even when the content of total chlorophyll was low, the ratio of chlorophyll a/chlorophyll b remained almost unchanged. In conjunction with the chlorophyll reductions, a decrease in the chlorophyll/carotenoid ratio and an increase in the xanthophyll/carotene ratio occurred. The periods of needle-chlorophyll reduction did not correlate with those periods of highest concentrations of atmospheric sulphur dioxide, the main air pollutant at the stand. However, chlorophyll formation ceased in the older needle age classes of chlorotic trees when the new flush was sprouting, indicating that nutritional deficiencies affect needle yellowing more than possible direct needle damage by air pollutants.