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1

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Photosynthetic responses of Coffea arabica leaves to a short-term high light exposure in relation to N availability (1997)

Ramalho, José C. ; Pons, Thijs L. ; Groeneveld, Henri W. ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Physiologia plantarum 101 (1997), S. 0

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ISSN: 1399-3054

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: It is known that the coffee (Coffea arabica L.) plant which is originally from shade habitats would have a limited ability to grow under full sun. Previous work has shown that nitrogen fertilisation can reduce the leaf damage when the plants are exposed to high light intensities during several days. In the present work we aimed to study the effects of the high irradiance during the first hours and evaluate the positive contribution of nitrogen fertilisation in the case of short-term exposure to strong light. Young plants (1.5–2 years old) grown in 1.5 kg of a mixed soil were supplemented with a nutrient solution containing 15 mM nitrogen in the form of NH4NO3, every 7 days (2N treatment), 15 days (1N treatment) and 45 days (0N treatment). Top mature leaves were exposed to a photosynthetic photon flux density of 1 500 μmol m−2 s−1 for a maximal period of 8 h, and changes in photosynthesis and pigment composition were monitored along the period of high light exposure. Photosynthetic capacity, leaf conductance to water vapour, electron transport capacity and maximum carboxylation activity, as well as some leaf fluorescence parameters (minimal fluorescence, photochemical efficiency of PSII and quantum yield of photosynthetic electron transport) were reduced by the stress, with a generally stronger impact observed in the 0N plants. The photochemical quenching was affected only in the 0N plants, while the non-photochemical quenching increased in 2N plants but decreased in the 0N ones. The results showed that 2N plants presented a better initial status of the photosynthetic parameters and of the content of photoprotective pigments. Those plants showed ability to trigger some protective mechanisms, as observed by the tendency to increase the xanthophyll pool content, specially in zeaxanthin and in non-photochemical quenching. Also, protein content presented a tendency to increase after 1.5 h, which was maintained until the end of the high light period. We conclude that nitrogen availability is a key factor in the acclimation process to high light.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1399-3054.1997.tb01841.x

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2

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Analysis of differences in photosynthetic nitrogen-use efficiency between four contrasting species (2004)

Pons, Thijs L. ; Westbeek, Milka H. M.

Oxford, UK; Malden, USA : Munksgaard International Publishers

Physiologia plantarum 122 (2004), S. 0

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ISSN: 1399-3054

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Causes of differences in photosynthetic nitrogen-use efficiency (PNUE), the rate of photosynthesis per unit leaf N, were investigated in four species. These were in order of decreasing PNUE; the two herbs Galinsoga ciliata and Origanum vulgare, and the two trees Populus nigra and Quercus robur. Plants were grown in pots outdoors at three levels of nutrient availability. The light- and CO2 response of gas exchange of leaves were measured, and their nitrogen and chlorophyll contents were determined. Furthermore, the internal conductance for CO2 diffusion was estimated. Nutrients did not have a large effect on PNUE except in Galinsoga. Leaf mass per unit area was negatively correlated with PNUEmax, which is likely to be partly caused by N present in cell wall proteins among other non-photosynthetic N compounds. The trees had a larger fraction of photosynthetic N in light harvesting components compared to the herbs. This contributed also substantially to the difference in PNUE at light saturation (PNUEmax) between the two groups, but not for PNUE calculated for an overcast day. Intercellular CO2 concentration was high in Galinsoga and Populus, which contributed significantly to their higher PNUEmax, particularly at low nutrient availability. The large gradient in CO2 concentration between intercellular spaces and chloroplasts was another factor that explained a substantial part of the differences in PNUEmax between Quercus and the other species that had smaller gradients. Stomatal and internal conductances for CO2 explained most of the difference in PNUEmax between Quercus and Populus at high nutrient availability for which these data were available.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1399-3054.2004.00380.x

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Nitrogen allocation in response to partial shading of a plant: Possible mechanisms (1996)

Pons, Thijs L. ; Bergkotte, Marc

Oxford, UK : Blackwell Publishing Ltd

Physiologia plantarum 98 (1996), S. 0

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ISSN: 1399-3054

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: The significance of photosynthetic and transpiration rates for the perception by plants of light gradients in leaf canopies has been investigated with regard to nitrogen allocation and re-allocation. A gradient of photon flux density (PFD) over a plant's foliage was simulated by shading one leaf of a pair of primary leaves of bean (Phaseolus vulgaris L. cv. Rentegever). Photosynthetic rate was manipulated independently of PFD and, to some extent, also of transpiration, by subjecting the leaf to different CO2 concentrations. Transpiration rate was changed independently of PFD and photosynthetic rate by subjecting the leaf to different vapour pressure differences (VPD). A reduced partial pressure of CO2 reduced specific leaf mass (SLM) as did a decreased PFD, but did not change leaf N per unit area (NLA) and light saturated rate of photosynthesis (Amax). A reduced VPD caused several effects consistent with the effect of PFD. It decreased NLA and Amax and increased the chlorophyll to N ratio in old and young leaves. Furthermore, it decreased the chlorophyll a to b ratio and inhibited leaf growth in young leaves. The transpiration stream is partitioned among the leaves of a plant according to their transpiration rates. The results suggest that relative rates of import of xylem sap into leaves of a plant play an important role in the perception of partial shading of a plant, a situation normally found in dense vegetations. The possible role of cytokinin influx into leaves as controlled by transpiration rate, is discussed.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1399-3054.1996.tb05713.x

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4

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Photosynthetic characteristics of leaves of male-sterile and hermaphrodite sex types of Plantago lanceolata grown under conditions of contrasting nitrogen and light availabilities (1996)

Poot, Pieter ; Pilon, Jorn ; Pons, Thijs L.

Oxford, UK : Blackwell Publishing Ltd

Physiologia plantarum 98 (1996), S. 0

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ISSN: 1399-3054

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Plantago lanceolata is a gynodioecious species: In natural populations male steriles (MS) coexist with hermaphrodites (H). Since male steriles have a reproductive disadvantage, without any compensation for their loss in male function by an increase in female function, they are expected to disappear from the population. In this study we investigated the possibility that differences in ecologically important photosynthetic characteristics, between MS and H lines of P. lanceolata. play a role in maintaining gynodioecy. One MS line and two H lines were grown under conditions of high N and light availability, as well as under either N limitation or light limitation, to investigate whether the sex types respond differently to environmental constraints. Photosynthetic light-response and CO2-response curves were made, together with leaf organic N and chlorophyll determinations. There were only few small differences between the lines and since the MS line did not differ in any of the determined photosynthetic characteristics from either H line, it is unlikely that these differences are involved in maintaining male sterility in populations of P. lanceolata. The low-light-grown plants showed a high degree of acclimation as shown by a two-fold higher leaf area to leaf weight ratio (SLA), a two-fold higher investment of N in light harvesting, and higher net photosynthetic rates under low-light conditions, as compared to the high-light-grown plants. The low-N-grown plants used their organic N more efficiently in photosynthesis compared to plants grown at an optimal N supply. This was mainly due to the N-limited plants having leaves with a lower organic N content and thus lower photosynthetic capacities. To a lesser extent it was due to the higher value for the curvature factor of the light-response curves of the N-limited plants, to their decreased rates of photorespiration and possibly to their relatively higher allocation of organic N to photosynthetic functions.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1399-3054.1996.tb06685.x

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5

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Photosynthetic induction in saplings of three shade-tolerant tree species: comparing understorey and gap habitats in a French Guiana rain forest (2000)

Rijkers, Toon ; de Vries, Peter Jan ; Pons, Thijs L. ; [et al.]

Springer

Oecologia 125 (2000), S. 331-340

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ISSN: 1432-1939

Keywords: Induction state Leaf age Stomatal conductance Sunflecks Sun/shade acclimation

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract. The photosynthetic induction response under constant and fluctuating light was examined in naturally occurring saplings (about 0.5–2 m in height) of three shade-tolerant tree species, Pourouma bicolor spp digitata, Dicorynia guianensis, and Vouacapoua americana, growing in bright gaps and in the shaded understorey in a Neotropical rain forest. Light availability to saplings was estimated by hemispherical photography. Photosynthetic induction was measured in the morning on leaves that had not yet experienced direct sunlight. In Dicorynia, the maximum net photosynthesis rate (A max) was similar between forest environments (ca 4 µmol m–2 s–1), whereas for the two other species, it was twice as high in gaps (ca 7.5) as in the understorey (ca 4.5). However, the time required to reach 90% of A max did not differ among species, and was short, 7–11 min. Biochemical induction was fast in leaves of Pourouma, as about 3 min were needed to reach 75% of maximum carboxylation capacity (V cmax); the two other species needed 4–5 min. When induction continued after reaching 75% of V cmax, stomatal conductance increased in Pourouma only (ca 80%), causing a further increase in its net photosynthesis rate. When fully induced leaves were shaded for 20 min, loss of induction was moderate in all species. However, gap saplings of Dicorynia had a rapid induction loss (ca 80%), which was mainly due to biochemical limitation as stomatal conductance decreased only slowly. When leaves were exposed to a series of lightflecks separated by short periods of low light, photosynthetic induction increased substantially and to a similar extent in all species. Although A max was much lower in old than in young leaves as measured in Dicorynia and Vouacapoua, variables of the dynamic response of photosynthesis to a change in light tended to be similar between young and old leaves. Old leaves, therefore, might remain important for whole-plant carbon gain, especially in understorey environments. The three shade-tolerant species show that, particularly in low light, they are capable of efficient sunfleck utilization.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004420000459

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6

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Analysis of differences in photosynthetic nitrogen use efficiency of alpine and lowland Poa species (1999)

Westbeek, Milka H. M. ; Pons, Thijs L. ; Cambridge, Marion L. ; [et al.]

Springer

Oecologia 120 (1999), S. 19-26

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ISSN: 1432-1939

Keywords: Key words Alpine ; Nitrogen ; Lowland ; Photosynthesis ; Photosynthetic nitrogen use efficiency

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract This study investigates factors determining variation in photosynthetic nitrogen use efficiency (φN) in seven slow- and fast-growing Poa species from altitudinally contrasting sites. The species and their environmental origin were (in order of increasing relative growth rate): two alpine (Poa fawcettiae and P. costiniana), one sub-alpine (P. alpina) and three temperate lowland perennials (P. pratensis, P. compressa and P. trivialis), as well as one temperate lowland annual (P. annua). Plants were grown hydroponically under identical conditions with free access to nutrients in a growth room. Photosynthesis per unit leaf area measured at growth irradiance (500 μmol m−2 s−1) was slightly higher in the slow-growing alpine species. At saturating light intensities, photosynthesis was considerably higher in the alpine species than in the lowland species. Carboxylation capacity and Rubisco content per unit leaf area were also greater in the alpine species. Despite variation between the species, the in vivo specific activity of Rubisco showed little relationship to relative growth rate or photosynthetic rate. Both at light saturation and at the growth irradiance, φN was lowest in the slow-growing alpine species P. fawcettiae, P. costiniana and P. alpina, and highest in the fast-growing P. compressa and P. annua. The proportion of leaf nitrogen that was allocated to photosynthetic capacity and the in vivo catalytic constant of Rubisco accounted for most of the variation in φN at light saturation. Minor variations in intercellular CO2 partial pressure also contributed to some extent to the variations in φN at light saturation. The low φN values at growth irradiance exhibited by the alpine species were additionally due to a lower percentage utilisation of their high photosynthetic capacity compared to the lowland species.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004420050828

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7

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Establishment of Plantago lanceolata L. and Plantago major L. among grass (1988)

Pons, Thijs L. ; Toorn, Jan

Springer

Oecologia 75 (1988), S. 394-399

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ISSN: 1432-1939

Keywords: Dormancy ; Germination ; Plantago ; Red/far-red ratio ; Temperature

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary The influence of temperature, stratification, red/far-red ratio of the light (R/FR) and combinations of these factors on the germination of Plantago lanceolata and Plantago major ssp major have been investigated under controlled conditions. Only quantitative differences were found in the response of the species to the various environmental factors investigated except for germination in darkness. P. lanceolata germinated in darkness, the percentage depending on environmental factors and seed collection, whereas P. major seed swere found to have a virtually absolute light requirement. P. lanceolata germinated at lower temperatures and was less inhibited at a low R/FR than P. major. Pot experiments and a field experiment were carried out in order to study the influence of the presence of grass on germination and emergence. P. major was more inhibited than P. lanceolata when sown among grass and the presence of vegetation did not inhibit the germination of P. lanceolata in the field experiment. The latter could be ascribed to the dormancy alleviating effect of low winter temperatures to which the seeds had been subjected. The inhibition of emergence of P. major among grass could be explained by the light factor only, whereas in the case of P. lanceolata an additional factor must be involved.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00376942

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8

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Establishment of Plantago lanceolata L. and Plantago major L. among grass (1988)

Toorn, Jan ; Pons, Thijs L.

Springer

Oecologia 76 (1988), S. 341-347

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ISSN: 1432-1939

Keywords: Germination ; Plantago ; Selection ; Shade tolerance ; Vegetation structure

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary Establishment of Plantago lanceolata and P. major ssp major among grass was studied in a field experiment in which survival and selection on date of seedling emergence and plant size was investigated in relation to the vegetation structure. P. major — in contrast to P. lanceolata — was not able to establish itself in grass because of its lower competitive ability caused by later germination, smaller seedling size, and shorter leaves. In both species there was selection for early germination. For P. lanceolata a significant correlation was found between the strength of selection and the light climate, determined by the structure of the grass sward. Plants that germinated early were at an advantage because they were larger, especially the leaves, when compared with plants that germinated late. It seems likely that selection was mainly by competition for light. Contrary to expectation P. major-seedlings had a higher shade tolerance than those of P. lanceolata. The performance of both species is discussed in relation to their different life strategies.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00377027

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Importance of the gradient in photosynthetically active radiation in a vegetation stand for leaf nitrogen allocation in two monocotyledons (1993)

Pons, Thijs L. ; Rijnberk, Hans ; Scheurwater, Ingeborg ; [et al.]

Springer

Oecologia 95 (1993), S. 416-424

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ISSN: 1432-1939

Keywords: Brachypodium pinnatum ; Carex acutiformis ; Nitrogen allocation ; Photosynthesis

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Carex acutiformis and Brachypodium pinnatum were grown with a uniform distribution of photosynthetic photon flux density (PFD) with height, and in a vertical PFD gradient similar to the PFD gradient in a leaf canopy. Distribution of organic leaf N and light-saturated rates of photosynthesis were determined. These parameters were also determined on plants growing in a natural vegetation stand. The effect of a PFD gradient was compared with the effect of a leaf canopy. In Brachypodium, plants growing in a vegetation stand had increasing leaf N with plant height. However, distribution of leaf N was not influenced by the PFD gradient treatment. The gradient of leaf N in plants growing in a leaf canopy was not due to differences within the long, mostly erect, leaves but to differences between leaves. In Carex, however, the PFD gradient caused a clear increase of leaf N with height in individual leaves and thus also in plants. The leaf N gradient was similar to that of plants growing in a leaf canopy. Leaf N distribution was not affected by nutrient availability in Carex. In most cases, photosynthesis was positively related to leaf N. Hence, lightsaturated rates of photosynthesis increased towards the top of the plants growing in leaf canopies in both species and, in Carex, also in the PFD gradient, thus contributing to increased N use efficiency for photosynthesis of the whole plant. It is concluded that in Carex the PFD gradient is the main environmental signal for leaf N allocation in response to shading in a leaf canopy, but one or more other signals must be involved in Brachypodium.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00320997

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