Stomatal conductance correlates with photosynthetic capacity

Wong, Siu-Chung; Cowan, I. R.; Farquhar, Graham D.

doi:10.1038/282424a0

Cited by 1,270 publications

(830 citation statements)

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“…The mechanisms underlying the responses of ^ to altered leaf N status remain largely unknown, the results obtained here in pine show that these mechanisms do not always bring about a positive coupling between^ and the CO^ assimilation capacity as was proposed by Wong, Cowan & Farquhar {1979).…”

Section: Discl'ssionmentioning

confidence: 50%

Differential response of leaf conductance, carbon isotope discrimination and water‐use efficiency to nitrogen deficiency in maritime pine and pedunculate oak plants

Guehl

Fort

Ferhi³

1995

New Phytologist

130

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SVMMARYGrowth, COj assimilation rate {A), leaf conductance {g), transpiration efficiency (W = ratio biomass production/plant water use) and carbon isotope discrimination (A) were assessed in maritime pine (Pinus pinaster Ait.) and pedunculate oak (Quercus robur L.) grown on a sand-peat mixture with three levels of fertilization : FlOO, optimal complete fertilization; F25, 25 "o of the optima! fertilizer supply; FO, no fertilization. Leaf phosphorus (P) and potassium (K) concentrations were affected little by the diminishing nutrient availability. Reduced fertilization decreased plant nitrogen (N) concentration in both species but leaf N concentration was less affected in oak than in pine. In pine W was markedly reduced in response to reduced leaf or whole plant N concentration, which was consistent with the sharp decrease also observed for plant intrinsic water-use efficiency (ratio A/g) both at the instantaneous (gas exchange data) and time-integrated (A/g derived from A measurements) levels. In this species, lowered W in the N deficient conditions was primarily associated with enhanced values of g. The existence of such a stomatal response pattern, confirmed by the increase in plant transpiration between FlOO and F25, has not been reported before. In oak, both A and g were decreased in F25 and FO as compared with FlOO. W was not affected -and instantaneous as well as time-integrated A/g values were oni}' slightly decreased -in relation to decreasing plant N concentration. For FlOO, no difference in W was noticed between pine and oak though the A values were 2-6°^ lower in oak. We speculate that this discrepancy was linked with higher plant-carbon losses through processes like respiration, fine-root mortality or root exudation in oak. The isotopic approach proved useful for assessing the effects of nutritional status on W^ but has to be used with caution w hen comparing different species.Key words: Pinuspinaster (maritime pine), Quercus robur [pedunculate o-dk), nitrogen deficiency, gas exchange and water-use efficiency, carbon isotope discrimination.

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Section: Discl'ssionmentioning

confidence: 50%

Differential response of leaf conductance, carbon isotope discrimination and water‐use efficiency to nitrogen deficiency in maritime pine and pedunculate oak plants

Guehl

Fort

Ferhi³

1995

New Phytologist

130

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“…Wong et al (1979) showed that P i remained constant whilst A and g s varied together, and that stomatal aperture is determined by the capacity of the mesophyll tissue to fix carbon. Our results could therefore be a reflection of direct effects of leaf water status on A mediated via non-stomatal (metabolic) limitations that are independent of P i (Lawlor & Tezara, 2009).…”

Section: Discussionmentioning

confidence: 99%

Reduced plant water status under sub-ambientpCO₂limits plant productivity in the wild progenitors of C₃and C₄cereals

Cunniff

Charles

Jones

et al. 2016

Ann Bot

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Background and Aims The reduction of plant productivity by low atmospheric CO 2 partial pressure (pCO 2 ) during the last glacial period is proposed as a limiting factor for the establishment of agriculture. Supporting this hypothesis, previous work has shown that glacial pCO 2 limits biomass in the wild progenitors of C 3 and C 4 founder crops, in part due to the direct effects of glacial pCO 2 on photosynthesis. Here, we investigate the indirect role of pCO 2 mediated via water status, hypothesizing that faster soil water depletion at glacial (18 Pa) compared to postglacial (27 Pa) pCO 2 , due to greater stomatal conductance, feeds back to limit photosynthesis during drying cycles.Methods We grew four wild progenitors of C 3 and C 4 crops at glacial and post-glacial pCO 2 and investigated physiological changes in gas exchange, canopy transpiration, soil water content and water potential between regular watering events. Growth parameters including leaf area were measured.Key Results Initial transpiration rates were higher at glacial pCO 2 due to greater stomatal conductance. However, stomatal conductance declined more rapidly over the soil drying cycle in glacial pCO 2 and was associated with decreased intercellular pCO 2 and lower photosynthesis. Soil water content was similar between pCO 2 levels as larger leaf areas at post-glacial pCO 2 offset the slower depletion of water. Instead the feedback could be linked to reduced plant water status. Particularly in the C 4 plants, soil-leaf water potential gradients were greater at 18 Pa compared with 27 Pa pCO 2 , suggesting an increased ratio of leaf evaporative demand to supply.Conclusions Reduced plant water status appeared to cause a negative feedback on stomatal aperture in plants at glacial pCO 2 , thereby reducing photosynthesis. The effects were stronger in C 4 species, providing a mechanism for reduced biomass at 18 Pa. These results have added significance when set against the drier climate of the glacial period.

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“…3 and 5). Both these characters have often been shown to be important in regulating the Phs (29,31).…”

Section: Discussionmentioning

confidence: 99%

Differences in Water Relations and Physiological Characteristics in Leaves of Wheat Associated with Leaf Position on the Plant

Aggarwal¹,

Sinha²

1984

Plant Physiol.

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The seasonal change in leaf water potential and its components, stomatal resistance, specific leaf weight, photosynthesis rate, the activities of ribulose-1,5-bisphosphate carboxylase and nitrate reductase, and soluble proteins were measured in flag leaves (ninth from base in position), seventh and fifth leaves of wheat Trticam aestipum L. cv Kalyansona. Flag leaves had a lower water and solute potential and lower or equal turgor pressure than seventh and fifth leaves. These differences were found to be independent of environment. The rate of photosynthesis and nitrate reductase activity were always lower in fifth and seventh leaves than in flag leaf. The photosynthetic efficiency in flag leaves appeared to be associated with lower stomatal resistance and higher specific leaf weight. The relations between leaf water potential and relative water content showed a change with leaf position. This change possibly allows flag leaf to maintain its functional efficiency despite its lower water potential.The physiological activity ofa leaf, particularly photosynthesis, depends on leaf age, genotype, and assimilate demand by sinks in addition to effects of environment (1 1, 23, 32). Leaf water status influences all aspects of growth and development (2,13,22). At t' of -1.0 to -1.5 MPa, most physiological processes such as leaf expansion, stomatal conductance, photosynthesis rate, and nitrogen metabolism are reduced (5, 13).In a recent study (Aggarwal et aL, unpublished), it was observed that the leaf 4' decreased to -2.0 MPa at flowering in irrigated wheat plants when dry matter production was at its peak and the flag leaf was most active (10, 25). A similar change in water relations at flowering has also been observed in sorghum (12, 24) and soybean (33). These studies also indicated that though leaf 4 was reduced at flowering, the physiological activity of the leaf was not impaired, rather it was improved. This observation contrasts with earlier studies showing sensitivity of physiological processes to small decreases in water potential (4, 13). It is, therefore, necessary to study the various physiological activities simultaneously with water relations at different growth stages.In the present investigation, seasonal changes in 4', 4',, and P have been studied concurrently with the Phs, the activities of RUBISCO and NR, r, and SLW in flag leaf and lower leaves of wheat. Pressure-volume curves were made to determine any change in water relations associated with the change in leaf position. An 15, 1980. Fertilizer at a rate of 75:60:60 kg/ha N:P:K was broadcast in the field prior to sowing. After germination, the distance between plants was maintained at 2.5 to 3.0 cm. In 20-d-old plants, main stems that were to be used subsequently for the measurements, were tagged. The field was irrigated as per agronomic practice at crown

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Stomatal conductance correlates with photosynthetic capacity

Cited by 1,270 publications

References 16 publications

Differential response of leaf conductance, carbon isotope discrimination and water‐use efficiency to nitrogen deficiency in maritime pine and pedunculate oak plants

Differential response of leaf conductance, carbon isotope discrimination and water‐use efficiency to nitrogen deficiency in maritime pine and pedunculate oak plants

Reduced plant water status under sub-ambientpCO₂limits plant productivity in the wild progenitors of C₃and C₄cereals

Differences in Water Relations and Physiological Characteristics in Leaves of Wheat Associated with Leaf Position on the Plant

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Stomatal conductance correlates with photosynthetic capacity

Cited by 1,270 publications

References 16 publications

Differential response of leaf conductance, carbon isotope discrimination and water‐use efficiency to nitrogen deficiency in maritime pine and pedunculate oak plants

Differential response of leaf conductance, carbon isotope discrimination and water‐use efficiency to nitrogen deficiency in maritime pine and pedunculate oak plants

Reduced plant water status under sub-ambientpCO2limits plant productivity in the wild progenitors of C3and C4cereals

Differences in Water Relations and Physiological Characteristics in Leaves of Wheat Associated with Leaf Position on the Plant

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Reduced plant water status under sub-ambientpCO₂limits plant productivity in the wild progenitors of C₃and C₄cereals